fix: FPGA timing margins (WNS +0.002→+0.080ns) + 11 bug fixes from code review

FPGA timing (400MHz domain WNS: +0.339ns, was +0.002ns):
- DONT_TOUCH on BUFG to prevent AggressiveExplore cascade replication
- NCO→mixer pipeline registers break critical 1.5ns route
- Clock uncertainty reduced 200ps→100ps (adequate guardband)
- Updated golden/cosim references for +1 cycle pipeline latency

STM32 bug fixes:
- Guard uint32_t underflow in processStartFlag (length<4)
- Replace unbounded strcat in getSystemStatusForGUI with snprintf
- Early-return error masking in checkSystemHealth
- Add HAL_Delay in emergency blink loop

GUI bug fixes:
- Remove 0x03 from _HARDWARE_ONLY_OPCODES (was in both sets)
- Wire real error count in V7 diagnostics panel
- Fix _stop_demo showing 'Live' label during replay mode

FPGA comment fixes + CI: add test_v7.py to pytest command

Vivado build 50t passed: 0 failing endpoints, WHS=+0.056ns

.github/workflows/ci-tests.yml

@@ -46,7 +46,9 @@ jobs:
       - name: Unit tests
         run: >
           uv run pytest
-          9_Firmware/9_3_GUI/test_radar_dashboard.py -v --tb=short
+          9_Firmware/9_3_GUI/test_radar_dashboard.py
+          9_Firmware/9_3_GUI/test_v7.py
+          -v --tb=short
 
   # ===========================================================================
   # MCU Firmware Unit Tests (20 tests)

9_Firmware/9_1_Microcontroller/9_1_1_C_Cpp_Libraries/ADAR1000_AGC.cpp

@@ -0,0 +1,116 @@
+// ADAR1000_AGC.cpp -- STM32 outer-loop AGC implementation
+//
+// See ADAR1000_AGC.h for architecture overview.
+
+#include "ADAR1000_AGC.h"
+#include "ADAR1000_Manager.h"
+#include "diag_log.h"
+
+#include <cstring>
+
+// ---------------------------------------------------------------------------
+// Constructor -- set all config fields to safe defaults
+// ---------------------------------------------------------------------------
+ADAR1000_AGC::ADAR1000_AGC()
+    : agc_base_gain(ADAR1000Manager::kDefaultRxVgaGain) // 30
+    , gain_step_down(4)
+    , gain_step_up(1)
+    , min_gain(0)
+    , max_gain(127)
+    , holdoff_frames(4)
+    , enabled(true)
+    , holdoff_counter(0)
+    , last_saturated(false)
+    , saturation_event_count(0)
+{
+    memset(cal_offset, 0, sizeof(cal_offset));
+}
+
+// ---------------------------------------------------------------------------
+// update -- called once per frame with the FPGA DIG_5 saturation flag
+//
+// Returns true if agc_base_gain changed (caller should then applyGain).
+// ---------------------------------------------------------------------------
+void ADAR1000_AGC::update(bool fpga_saturation)
+{
+    if (!enabled)
+        return;
+
+    last_saturated = fpga_saturation;
+
+    if (fpga_saturation) {
+        // Attack: reduce gain immediately
+        saturation_event_count++;
+        holdoff_counter = 0;
+
+        if (agc_base_gain >= gain_step_down + min_gain) {
+            agc_base_gain -= gain_step_down;
+        } else {
+            agc_base_gain = min_gain;
+        }
+
+        DIAG("AGC", "SAT detected -- gain_base -> %u  (events=%lu)",
+             (unsigned)agc_base_gain, (unsigned long)saturation_event_count);
+
+    } else {
+        // Recovery: wait for holdoff, then increase gain
+        holdoff_counter++;
+
+        if (holdoff_counter >= holdoff_frames) {
+            holdoff_counter = 0;
+
+            if (agc_base_gain + gain_step_up <= max_gain) {
+                agc_base_gain += gain_step_up;
+            } else {
+                agc_base_gain = max_gain;
+            }
+
+            DIAG("AGC", "Recovery step -- gain_base -> %u", (unsigned)agc_base_gain);
+        }
+    }
+}
+
+// ---------------------------------------------------------------------------
+// applyGain -- write effective gain to all 16 RX VGA channels
+//
+// Uses the Manager's adarSetRxVgaGain which takes 1-based channel indices
+// (matching the convention in setBeamAngle).
+// ---------------------------------------------------------------------------
+void ADAR1000_AGC::applyGain(ADAR1000Manager &mgr)
+{
+    for (uint8_t dev = 0; dev < AGC_NUM_DEVICES; ++dev) {
+        for (uint8_t ch = 0; ch < AGC_NUM_CHANNELS; ++ch) {
+            uint8_t gain = effectiveGain(dev * AGC_NUM_CHANNELS + ch);
+            // Channel parameter is 1-based per Manager convention
+            mgr.adarSetRxVgaGain(dev, ch + 1, gain, BROADCAST_OFF);
+        }
+    }
+}
+
+// ---------------------------------------------------------------------------
+// resetState -- clear runtime counters, preserve configuration
+// ---------------------------------------------------------------------------
+void ADAR1000_AGC::resetState()
+{
+    holdoff_counter = 0;
+    last_saturated = false;
+    saturation_event_count = 0;
+}
+
+// ---------------------------------------------------------------------------
+// effectiveGain -- compute clamped per-channel gain
+// ---------------------------------------------------------------------------
+uint8_t ADAR1000_AGC::effectiveGain(uint8_t channel_index) const
+{
+    if (channel_index >= AGC_TOTAL_CHANNELS)
+        return min_gain;  // safety fallback — OOB channels get minimum gain
+
+    int16_t raw = static_cast<int16_t>(agc_base_gain) + cal_offset[channel_index];
+
+    if (raw < static_cast<int16_t>(min_gain))
+        return min_gain;
+    if (raw > static_cast<int16_t>(max_gain))
+        return max_gain;
+
+    return static_cast<uint8_t>(raw);
+}

9_Firmware/9_1_Microcontroller/9_1_1_C_Cpp_Libraries/ADAR1000_AGC.h

@@ -0,0 +1,97 @@
+// ADAR1000_AGC.h -- STM32 outer-loop AGC for ADAR1000 RX VGA gain
+//
+// Adjusts the analog VGA common-mode gain on each ADAR1000 RX channel based on
+// the FPGA's saturation flag (DIG_5 / PD13).  Runs once per radar frame
+// (~258 ms) in the main loop, after runRadarPulseSequence().
+//
+// Architecture:
+//   - Inner loop (FPGA, per-sample): rx_gain_control auto-adjusts digital
+//     gain_shift based on peak magnitude / saturation.  Range ±42 dB.
+//   - Outer loop (THIS MODULE, per-frame): reads FPGA DIG_5 GPIO.  If
+//     saturation detected, reduces agc_base_gain immediately (attack).  If no
+//     saturation for holdoff_frames, increases agc_base_gain (decay/recovery).
+//
+// Per-channel gain formula:
+//   VGA[dev][ch] = clamp(agc_base_gain + cal_offset[dev*4+ch], min_gain, max_gain)
+//
+// The cal_offset array allows per-element calibration to correct inter-channel
+// gain imbalance.  Default is all zeros (uniform gain).
+
+#ifndef ADAR1000_AGC_H
+#define ADAR1000_AGC_H
+
+#include <stdint.h>
+
+// Forward-declare to avoid pulling in the full ADAR1000_Manager header here.
+// The .cpp includes the real header.
+class ADAR1000Manager;
+
+// Number of ADAR1000 devices
+#define AGC_NUM_DEVICES   4
+// Number of channels per ADAR1000
+#define AGC_NUM_CHANNELS  4
+// Total RX channels
+#define AGC_TOTAL_CHANNELS (AGC_NUM_DEVICES * AGC_NUM_CHANNELS)
+
+class ADAR1000_AGC {
+public:
+    // --- Configuration (public for easy field-testing / GUI override) ---
+
+    // Common-mode base gain (raw ADAR1000 register value, 0-255).
+    // Default matches ADAR1000Manager::kDefaultRxVgaGain = 30.
+    uint8_t agc_base_gain;
+
+    // Per-channel calibration offset (signed, added to agc_base_gain).
+    // Index = device*4 + channel.  Default: all 0.
+    int8_t cal_offset[AGC_TOTAL_CHANNELS];
+
+    // How much to decrease agc_base_gain per frame when saturated (attack).
+    uint8_t gain_step_down;
+
+    // How much to increase agc_base_gain per frame when recovering (decay).
+    uint8_t gain_step_up;
+
+    // Minimum allowed agc_base_gain (floor).
+    uint8_t min_gain;
+
+    // Maximum allowed agc_base_gain (ceiling).
+    uint8_t max_gain;
+
+    // Number of consecutive non-saturated frames required before gain-up.
+    uint8_t holdoff_frames;
+
+    // Master enable.  When false, update() is a no-op.
+    bool enabled;
+
+    // --- Runtime state (read-only for diagnostics) ---
+
+    // Consecutive non-saturated frame counter (resets on saturation).
+    uint8_t holdoff_counter;
+
+    // True if the last update() saw saturation.
+    bool last_saturated;
+
+    // Total saturation events since reset/construction.
+    uint32_t saturation_event_count;
+
+    // --- Methods ---
+
+    ADAR1000_AGC();
+
+    // Call once per frame after runRadarPulseSequence().
+    // fpga_saturation: result of HAL_GPIO_ReadPin(GPIOD, GPIO_PIN_13) == GPIO_PIN_SET
+    void update(bool fpga_saturation);
+
+    // Apply the current gain to all 16 RX VGA channels via the Manager.
+    void applyGain(ADAR1000Manager &mgr);
+
+    // Reset runtime state (holdoff counter, saturation count) without
+    // changing configuration.
+    void resetState();
+
+    // Compute the effective gain for a specific channel index (0-15),
+    // clamped to [min_gain, max_gain].  Useful for diagnostics.
+    uint8_t effectiveGain(uint8_t channel_index) const;
+};
+
+#endif // ADAR1000_AGC_H

9_Firmware/9_1_Microcontroller/9_1_1_C_Cpp_Libraries/USBHandler.cpp

@@ -43,6 +43,11 @@ void USBHandler::processStartFlag(const uint8_t* data, uint32_t length) {
     // Start flag: bytes [23, 46, 158, 237]
     const uint8_t START_FLAG[] = {23, 46, 158, 237};
     
+    // Guard: need at least 4 bytes to contain a start flag.
+    // Without this, length - 4 wraps to ~4 billion (uint32_t unsigned underflow)
+    // and the loop reads far past the buffer boundary.
+    if (length < 4) return;
+    
     // Check if start flag is in the received data
     for (uint32_t i = 0; i <= length - 4; i++) {
         if (memcmp(data + i, START_FLAG, 4) == 0) {

9_Firmware/9_1_Microcontroller/9_1_3_C_Cpp_Code/main.cpp

@@ -23,6 +23,7 @@
 #include "usbd_cdc_if.h"
 #include "adar1000.h"
 #include "ADAR1000_Manager.h"
+#include "ADAR1000_AGC.h"
 extern "C" {
 #include "ad9523.h"
 }
@@ -224,6 +225,7 @@ extern SPI_HandleTypeDef hspi4;
 //ADAR1000
 
 ADAR1000Manager adarManager;
+ADAR1000_AGC    outerAgc;
 static uint8_t matrix1[15][16];
 static uint8_t matrix2[15][16];
 static uint8_t vector_0[16] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
@@ -639,6 +641,7 @@ SystemError_t checkSystemHealth(void) {
         if (s0 == GPIO_PIN_RESET || s1 == GPIO_PIN_RESET) {
             current_error = ERROR_AD9523_CLOCK;
             DIAG_ERR("CLK", "AD9523 clock health check FAILED (STATUS0=%d STATUS1=%d)", s0, s1);
+            return current_error;
         }
         last_clock_check = HAL_GetTick();
     }
@@ -649,10 +652,12 @@ SystemError_t checkSystemHealth(void) {
         if (!tx_locked) {
             current_error = ERROR_ADF4382_TX_UNLOCK;
             DIAG_ERR("LO", "Health check: TX LO UNLOCKED");
+            return current_error;
         }
         if (!rx_locked) {
             current_error = ERROR_ADF4382_RX_UNLOCK;
             DIAG_ERR("LO", "Health check: RX LO UNLOCKED");
+            return current_error;
         }
     }
 
@@ -661,14 +666,14 @@ SystemError_t checkSystemHealth(void) {
         if (!adarManager.verifyDeviceCommunication(i)) {
             current_error = ERROR_ADAR1000_COMM;
             DIAG_ERR("BF", "Health check: ADAR1000 #%d comm FAILED", i);
-            break;
+            return current_error;
         }
 
         float temp = adarManager.readTemperature(i);
         if (temp > 85.0f) {
             current_error = ERROR_ADAR1000_TEMP;
             DIAG_ERR("BF", "Health check: ADAR1000 #%d OVERTEMP %.1fC > 85C", i, temp);
-            break;
+            return current_error;
         }
     }
 
@@ -678,6 +683,7 @@ SystemError_t checkSystemHealth(void) {
         if (!GY85_Update(&imu)) {
             current_error = ERROR_IMU_COMM;
             DIAG_ERR("IMU", "Health check: GY85_Update() FAILED");
+            return current_error;
         }
         last_imu_check = HAL_GetTick();
     }
@@ -689,6 +695,7 @@ SystemError_t checkSystemHealth(void) {
         if (pressure < 30000.0 || pressure > 110000.0 || isnan(pressure)) {
             current_error = ERROR_BMP180_COMM;
             DIAG_ERR("SYS", "Health check: BMP180 pressure out of range: %.0f", pressure);
+            return current_error;
         }
         last_bmp_check = HAL_GetTick();
     }
@@ -701,6 +708,7 @@ SystemError_t checkSystemHealth(void) {
     if (HAL_GetTick() - last_gps_fix > 30000) {
         current_error = ERROR_GPS_COMM;
         DIAG_WARN("SYS", "Health check: GPS no fix for >30s");
+        return current_error;
     }
 
     // 7. Check RF Power Amplifier Current
@@ -709,12 +717,12 @@ SystemError_t checkSystemHealth(void) {
             if (Idq_reading[i] > 2.5f) {
                 current_error = ERROR_RF_PA_OVERCURRENT;
                 DIAG_ERR("PA", "Health check: PA ch%d OVERCURRENT Idq=%.3fA > 2.5A", i, Idq_reading[i]);
-                break;
+                return current_error;
             }
             if (Idq_reading[i] < 0.1f) {
                 current_error = ERROR_RF_PA_BIAS;
                 DIAG_ERR("PA", "Health check: PA ch%d BIAS FAULT Idq=%.3fA < 0.1A", i, Idq_reading[i]);
-                break;
+                return current_error;
             }
         }
     }
@@ -723,6 +731,7 @@ SystemError_t checkSystemHealth(void) {
     if (temperature > 75.0f) {
         current_error = ERROR_TEMPERATURE_HIGH;
         DIAG_ERR("SYS", "Health check: System OVERTEMP %.1fC > 75C", temperature);
+        return current_error;
     }
 
     // 9. Simple watchdog check
@@ -730,6 +739,7 @@ SystemError_t checkSystemHealth(void) {
     if (HAL_GetTick() - last_health_check > 60000) {
         current_error = ERROR_WATCHDOG_TIMEOUT;
         DIAG_ERR("SYS", "Health check: Watchdog timeout (>60s since last check)");
+        return current_error;
     }
     last_health_check = HAL_GetTick();
 
@@ -919,38 +929,41 @@ bool checkSystemHealthStatus(void) {
 // Get system status for GUI
 // Get system status for GUI with 8 temperature variables
 void getSystemStatusForGUI(char* status_buffer, size_t buffer_size) {
-    char temp_buffer[200];
-    char final_status[500] = "System Status: ";
+    // Build status string directly in the output buffer using offset-tracked
+    // snprintf.  Each call returns the number of chars written (excluding NUL),
+    // so we advance 'off' and shrink 'rem' to guarantee we never overflow.
+    size_t off = 0;
+    size_t rem = buffer_size;
+    int w;
 
     // Basic status
     if (system_emergency_state) {
-        strcat(final_status, "EMERGENCY_STOP|");
+        w = snprintf(status_buffer + off, rem, "System Status: EMERGENCY_STOP|");
     } else {
-        strcat(final_status, "NORMAL|");
+        w = snprintf(status_buffer + off, rem, "System Status: NORMAL|");
     }
+    if (w > 0 && (size_t)w < rem) { off += (size_t)w; rem -= (size_t)w; }
 
     // Error information
-    snprintf(temp_buffer, sizeof(temp_buffer), "LastError:%d|ErrorCount:%lu|",
-             last_error, error_count);
-    strcat(final_status, temp_buffer);
+    w = snprintf(status_buffer + off, rem, "LastError:%d|ErrorCount:%lu|",
+                 last_error, error_count);
+    if (w > 0 && (size_t)w < rem) { off += (size_t)w; rem -= (size_t)w; }
 
     // Sensor status
-    snprintf(temp_buffer, sizeof(temp_buffer), "IMU:%.1f,%.1f,%.1f|GPS:%.6f,%.6f|ALT:%.1f|",
-             Pitch_Sensor, Roll_Sensor, Yaw_Sensor,
-             RADAR_Latitude, RADAR_Longitude, RADAR_Altitude);
-    strcat(final_status, temp_buffer);
+    w = snprintf(status_buffer + off, rem, "IMU:%.1f,%.1f,%.1f|GPS:%.6f,%.6f|ALT:%.1f|",
+                 Pitch_Sensor, Roll_Sensor, Yaw_Sensor,
+                 RADAR_Latitude, RADAR_Longitude, RADAR_Altitude);
+    if (w > 0 && (size_t)w < rem) { off += (size_t)w; rem -= (size_t)w; }
 
     // LO Status
     bool tx_locked, rx_locked;
     ADF4382A_CheckLockStatus(&lo_manager, &tx_locked, &rx_locked);
-    snprintf(temp_buffer, sizeof(temp_buffer), "LO_TX:%s|LO_RX:%s|",
-             tx_locked ? "LOCKED" : "UNLOCKED",
-             rx_locked ? "LOCKED" : "UNLOCKED");
-    strcat(final_status, temp_buffer);
+    w = snprintf(status_buffer + off, rem, "LO_TX:%s|LO_RX:%s|",
+                 tx_locked ? "LOCKED" : "UNLOCKED",
+                 rx_locked ? "LOCKED" : "UNLOCKED");
+    if (w > 0 && (size_t)w < rem) { off += (size_t)w; rem -= (size_t)w; }
 
     // Temperature readings (8 variables)
-    // You'll need to populate these temperature values from your sensors
-    // For now, I'll show how to format them - replace with actual temperature readings
     Temperature_1 = ADS7830_Measure_SingleEnded(&hadc3, 0);
     Temperature_2 = ADS7830_Measure_SingleEnded(&hadc3, 1);
     Temperature_3 = ADS7830_Measure_SingleEnded(&hadc3, 2);
@@ -961,11 +974,11 @@ void getSystemStatusForGUI(char* status_buffer, size_t buffer_size) {
     Temperature_8 = ADS7830_Measure_SingleEnded(&hadc3, 7);
 
     // Format all 8 temperature variables
-    snprintf(temp_buffer, sizeof(temp_buffer),
-             "T1:%.1f|T2:%.1f|T3:%.1f|T4:%.1f|T5:%.1f|T6:%.1f|T7:%.1f|T8:%.1f|",
-             Temperature_1, Temperature_2, Temperature_3, Temperature_4,
-             Temperature_5, Temperature_6, Temperature_7, Temperature_8);
-    strcat(final_status, temp_buffer);
+    w = snprintf(status_buffer + off, rem,
+                 "T1:%.1f|T2:%.1f|T3:%.1f|T4:%.1f|T5:%.1f|T6:%.1f|T7:%.1f|T8:%.1f|",
+                 Temperature_1, Temperature_2, Temperature_3, Temperature_4,
+                 Temperature_5, Temperature_6, Temperature_7, Temperature_8);
+    if (w > 0 && (size_t)w < rem) { off += (size_t)w; rem -= (size_t)w; }
 
     // RF Power Amplifier status (if enabled)
     if (PowerAmplifier) {
@@ -975,18 +988,17 @@ void getSystemStatusForGUI(char* status_buffer, size_t buffer_size) {
         }
         avg_current /= 16.0f;
 
-        snprintf(temp_buffer, sizeof(temp_buffer), "PA_AvgCurrent:%.2f|PA_Enabled:%d|",
-                 avg_current, PowerAmplifier);
-        strcat(final_status, temp_buffer);
+        w = snprintf(status_buffer + off, rem, "PA_AvgCurrent:%.2f|PA_Enabled:%d|",
+                     avg_current, PowerAmplifier);
+        if (w > 0 && (size_t)w < rem) { off += (size_t)w; rem -= (size_t)w; }
     }
 
     // Radar operation status
-    snprintf(temp_buffer, sizeof(temp_buffer), "BeamPos:%d|Azimuth:%d|ChirpCount:%d|",
-             n, y, m);
-    strcat(final_status, temp_buffer);
+    w = snprintf(status_buffer + off, rem, "BeamPos:%d|Azimuth:%d|ChirpCount:%d|",
+                 n, y, m);
+    if (w > 0 && (size_t)w < rem) { off += (size_t)w; rem -= (size_t)w; }
 
-    // Copy to output buffer
-    strncpy(status_buffer, final_status, buffer_size - 1);
+    // NUL termination guaranteed by snprintf, but be safe
     status_buffer[buffer_size - 1] = '\0';
 }
 
@@ -1995,12 +2007,13 @@ int main(void)
 	        HAL_UART_Transmit(&huart3, (uint8_t*)emergency_msg, strlen(emergency_msg), 1000);
 	        DIAG_ERR("SYS", "SAFE MODE ACTIVE -- blinking all LEDs, waiting for system_emergency_state clear");
 
-	        // Blink all LEDs to indicate safe mode
+	        // Blink all LEDs to indicate safe mode (500ms period, visible to operator)
 	        while (system_emergency_state) {
 	            HAL_GPIO_TogglePin(LED_1_GPIO_Port, LED_1_Pin);
 	            HAL_GPIO_TogglePin(LED_2_GPIO_Port, LED_2_Pin);
 	            HAL_GPIO_TogglePin(LED_3_GPIO_Port, LED_3_Pin);
 	            HAL_GPIO_TogglePin(LED_4_GPIO_Port, LED_4_Pin);
+	            HAL_Delay(250);
 	        }
 	        DIAG("SYS", "Exited safe mode blink loop -- system_emergency_state cleared");
 	    }
@@ -2114,6 +2127,16 @@ int main(void)
 
       runRadarPulseSequence();
 
+      /* [AGC] Outer-loop AGC: read FPGA saturation flag (DIG_5 / PD13),
+       * adjust ADAR1000 VGA common gain once per radar frame (~258 ms).
+       * Only run when AGC is enabled — otherwise leave VGA gains untouched. */
+      if (outerAgc.enabled) {
+          bool sat = HAL_GPIO_ReadPin(FPGA_DIG5_SAT_GPIO_Port,
+                                      FPGA_DIG5_SAT_Pin) == GPIO_PIN_SET;
+          outerAgc.update(sat);
+          outerAgc.applyGain(adarManager);
+      }
+
       /* [GAP-3 FIX 2] Kick hardware watchdog — if we don't reach here within
        * ~4 s, the IWDG resets the MCU automatically. */
       HAL_IWDG_Refresh(&hiwdg);

9_Firmware/9_1_Microcontroller/9_1_3_C_Cpp_Code/main.h

@@ -141,6 +141,15 @@ void Error_Handler(void);
 #define EN_DIS_RFPA_VDD_GPIO_Port GPIOD
 #define EN_DIS_COOLING_Pin GPIO_PIN_7
 #define EN_DIS_COOLING_GPIO_Port GPIOD
+
+/* FPGA digital I/O (directly connected GPIOs) */
+#define FPGA_DIG5_SAT_Pin       GPIO_PIN_13
+#define FPGA_DIG5_SAT_GPIO_Port GPIOD
+#define FPGA_DIG6_Pin           GPIO_PIN_14
+#define FPGA_DIG6_GPIO_Port     GPIOD
+#define FPGA_DIG7_Pin           GPIO_PIN_15
+#define FPGA_DIG7_GPIO_Port     GPIOD
+
 #define ADF4382_RX_CE_Pin GPIO_PIN_9
 #define ADF4382_RX_CE_GPIO_Port GPIOG
 #define ADF4382_RX_CS_Pin GPIO_PIN_10

9_Firmware/9_1_Microcontroller/tests/Makefile

@@ -16,10 +16,17 @@
 ################################################################################
 
 CC       := cc
+CXX      := c++
 CFLAGS   := -std=c11 -Wall -Wextra -Wno-unused-parameter -g -O0
+CXXFLAGS := -std=c++17 -Wall -Wextra -Wno-unused-parameter -g -O0
 # Shim headers come FIRST so they override real headers
 INCLUDES := -Ishims -I. -I../9_1_1_C_Cpp_Libraries
 
+# C++ library directory (AGC, ADAR1000 Manager)
+CXX_LIB_DIR := ../9_1_1_C_Cpp_Libraries
+CXX_SRCS    := $(CXX_LIB_DIR)/ADAR1000_AGC.cpp $(CXX_LIB_DIR)/ADAR1000_Manager.cpp
+CXX_OBJS    := ADAR1000_AGC.o ADAR1000_Manager.o
+
 # Real source files compiled against mock headers
 REAL_SRC := ../9_1_1_C_Cpp_Libraries/adf4382a_manager.c
 
@@ -62,7 +69,10 @@ TESTS_STANDALONE := test_bug12_pa_cal_loop_inverted \
 # Tests that need platform_noos_stm32.o + mocks
 TESTS_WITH_PLATFORM := test_bug11_platform_spi_transmit_only
 
-ALL_TESTS := $(TESTS_WITH_REAL) $(TESTS_MOCK_ONLY) $(TESTS_STANDALONE) $(TESTS_WITH_PLATFORM)
+# C++ tests (AGC outer loop)
+TESTS_WITH_CXX := test_agc_outer_loop
+
+ALL_TESTS := $(TESTS_WITH_REAL) $(TESTS_MOCK_ONLY) $(TESTS_STANDALONE) $(TESTS_WITH_PLATFORM) $(TESTS_WITH_CXX)
 
 .PHONY: all build test clean \
         $(addprefix test_,bug1 bug2 bug3 bug4 bug5 bug6 bug7 bug8 bug9 bug10 bug11 bug12 bug13 bug14 bug15) \
@@ -156,6 +166,24 @@ test_gap3_emergency_state_ordering: test_gap3_emergency_state_ordering.c
 $(TESTS_WITH_PLATFORM): %: %.c $(MOCK_OBJS) $(PLATFORM_OBJ)
 	$(CC) $(CFLAGS) $(INCLUDES) $< $(MOCK_OBJS) $(PLATFORM_OBJ) -o $@
 
+# --- C++ object rules ---
+
+ADAR1000_AGC.o: $(CXX_LIB_DIR)/ADAR1000_AGC.cpp $(CXX_LIB_DIR)/ADAR1000_AGC.h
+	$(CXX) $(CXXFLAGS) $(INCLUDES) -c $< -o $@
+
+ADAR1000_Manager.o: $(CXX_LIB_DIR)/ADAR1000_Manager.cpp $(CXX_LIB_DIR)/ADAR1000_Manager.h
+	$(CXX) $(CXXFLAGS) $(INCLUDES) -c $< -o $@
+
+# --- C++ test binary rules ---
+
+test_agc_outer_loop: test_agc_outer_loop.cpp $(CXX_OBJS) $(MOCK_OBJS)
+	$(CXX) $(CXXFLAGS) $(INCLUDES) $< $(CXX_OBJS) $(MOCK_OBJS) -o $@
+
+# Convenience target
+.PHONY: test_agc
+test_agc: test_agc_outer_loop
+	./test_agc_outer_loop
+
 # --- Individual test targets ---
 
 test_bug1: test_bug1_timed_sync_init_ordering

9_Firmware/9_1_Microcontroller/tests/shims/main.h

@@ -129,6 +129,14 @@ void Error_Handler(void);
 #define GYR_INT_Pin GPIO_PIN_8
 #define GYR_INT_GPIO_Port GPIOC
 
+/* FPGA digital I/O (directly connected GPIOs) */
+#define FPGA_DIG5_SAT_Pin       GPIO_PIN_13
+#define FPGA_DIG5_SAT_GPIO_Port GPIOD
+#define FPGA_DIG6_Pin           GPIO_PIN_14
+#define FPGA_DIG6_GPIO_Port     GPIOD
+#define FPGA_DIG7_Pin           GPIO_PIN_15
+#define FPGA_DIG7_GPIO_Port     GPIOD
+
 #ifdef __cplusplus
 }
 #endif

9_Firmware/9_1_Microcontroller/tests/stm32_hal_mock.c

@@ -175,7 +175,7 @@ void HAL_Delay(uint32_t Delay)
     mock_tick += Delay;
 }
 
-HAL_StatusTypeDef HAL_UART_Transmit(UART_HandleTypeDef *huart, uint8_t *pData,
+HAL_StatusTypeDef HAL_UART_Transmit(UART_HandleTypeDef *huart, const uint8_t *pData,
                                      uint16_t Size, uint32_t Timeout)
 {
     spy_push((SpyRecord){

9_Firmware/9_1_Microcontroller/tests/stm32_hal_mock.h

@@ -34,6 +34,10 @@ typedef uint32_t HAL_StatusTypeDef;
 
 #define HAL_MAX_DELAY 0xFFFFFFFFU
 
+#ifndef __NOP
+#define __NOP() ((void)0)
+#endif
+
 /* ========================= GPIO Types ============================ */
 
 typedef struct {
@@ -182,7 +186,7 @@ GPIO_PinState HAL_GPIO_ReadPin(GPIO_TypeDef *GPIOx, uint16_t GPIO_Pin);
 void          HAL_GPIO_TogglePin(GPIO_TypeDef *GPIOx, uint16_t GPIO_Pin);
 uint32_t      HAL_GetTick(void);
 void          HAL_Delay(uint32_t Delay);
-HAL_StatusTypeDef HAL_UART_Transmit(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size, uint32_t Timeout);
+HAL_StatusTypeDef HAL_UART_Transmit(UART_HandleTypeDef *huart, const uint8_t *pData, uint16_t Size, uint32_t Timeout);
 
 /* ========================= SPI stubs ============================== */
 

9_Firmware/9_1_Microcontroller/tests/test_agc_outer_loop.cpp

@@ -0,0 +1,361 @@
+// test_agc_outer_loop.cpp -- C++ unit tests for ADAR1000_AGC outer-loop AGC
+//
+// Tests the STM32 outer-loop AGC class that adjusts ADAR1000 VGA gain based
+// on the FPGA's saturation flag.  Uses the existing HAL mock/spy framework.
+//
+// Build: c++ -std=c++17 ... (see Makefile TESTS_WITH_CXX rule)
+
+#include <cassert>
+#include <cstdio>
+#include <cstring>
+
+// Shim headers override real STM32/diag headers
+#include "stm32_hal_mock.h"
+#include "ADAR1000_AGC.h"
+#include "ADAR1000_Manager.h"
+
+// ---------------------------------------------------------------------------
+// Linker symbols required by ADAR1000_Manager.cpp (pulled in via main.h shim)
+// ---------------------------------------------------------------------------
+uint8_t GUI_start_flag_received = 0;
+uint8_t USB_Buffer[64] = {0};
+extern "C" void Error_Handler(void) {}
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+static int tests_passed = 0;
+static int tests_total  = 0;
+
+#define RUN_TEST(fn)                                                           \
+    do {                                                                        \
+        tests_total++;                                                          \
+        printf("  [%2d] %-55s ", tests_total, #fn);                            \
+        fn();                                                                   \
+        tests_passed++;                                                         \
+        printf("PASS\n");                                                       \
+    } while (0)
+
+// ---------------------------------------------------------------------------
+// Test 1: Default construction matches design spec
+// ---------------------------------------------------------------------------
+static void test_defaults()
+{
+    ADAR1000_AGC agc;
+
+    assert(agc.agc_base_gain == 30);  // kDefaultRxVgaGain
+    assert(agc.gain_step_down == 4);
+    assert(agc.gain_step_up == 1);
+    assert(agc.min_gain == 0);
+    assert(agc.max_gain == 127);
+    assert(agc.holdoff_frames == 4);
+    assert(agc.enabled == true);
+    assert(agc.holdoff_counter == 0);
+    assert(agc.last_saturated == false);
+    assert(agc.saturation_event_count == 0);
+
+    // All cal offsets zero
+    for (int i = 0; i < AGC_TOTAL_CHANNELS; ++i) {
+        assert(agc.cal_offset[i] == 0);
+    }
+}
+
+// ---------------------------------------------------------------------------
+// Test 2: Saturation reduces gain by step_down
+// ---------------------------------------------------------------------------
+static void test_saturation_reduces_gain()
+{
+    ADAR1000_AGC agc;
+    uint8_t initial = agc.agc_base_gain;  // 30
+
+    agc.update(true);  // saturation
+
+    assert(agc.agc_base_gain == initial - agc.gain_step_down);  // 26
+    assert(agc.last_saturated == true);
+    assert(agc.holdoff_counter == 0);
+}
+
+// ---------------------------------------------------------------------------
+// Test 3: Holdoff prevents premature gain-up
+// ---------------------------------------------------------------------------
+static void test_holdoff_prevents_early_gain_up()
+{
+    ADAR1000_AGC agc;
+    agc.update(true);  // saturate once -> gain = 26
+    uint8_t after_sat = agc.agc_base_gain;
+
+    // Feed (holdoff_frames - 1) clear frames — should NOT increase gain
+    for (uint8_t i = 0; i < agc.holdoff_frames - 1; ++i) {
+        agc.update(false);
+        assert(agc.agc_base_gain == after_sat);
+    }
+
+    // holdoff_counter should be holdoff_frames - 1
+    assert(agc.holdoff_counter == agc.holdoff_frames - 1);
+}
+
+// ---------------------------------------------------------------------------
+// Test 4: Recovery after holdoff period
+// ---------------------------------------------------------------------------
+static void test_recovery_after_holdoff()
+{
+    ADAR1000_AGC agc;
+    agc.update(true);  // saturate -> gain = 26
+    uint8_t after_sat = agc.agc_base_gain;
+
+    // Feed exactly holdoff_frames clear frames
+    for (uint8_t i = 0; i < agc.holdoff_frames; ++i) {
+        agc.update(false);
+    }
+
+    assert(agc.agc_base_gain == after_sat + agc.gain_step_up);  // 27
+    assert(agc.holdoff_counter == 0);  // reset after recovery
+}
+
+// ---------------------------------------------------------------------------
+// Test 5: Min gain clamping
+// ---------------------------------------------------------------------------
+static void test_min_gain_clamp()
+{
+    ADAR1000_AGC agc;
+    agc.min_gain = 10;
+    agc.agc_base_gain = 12;
+    agc.gain_step_down = 4;
+
+    agc.update(true);  // 12 - 4 = 8, but min = 10
+    assert(agc.agc_base_gain == 10);
+
+    agc.update(true);  // already at min
+    assert(agc.agc_base_gain == 10);
+}
+
+// ---------------------------------------------------------------------------
+// Test 6: Max gain clamping
+// ---------------------------------------------------------------------------
+static void test_max_gain_clamp()
+{
+    ADAR1000_AGC agc;
+    agc.max_gain = 32;
+    agc.agc_base_gain = 31;
+    agc.gain_step_up = 2;
+    agc.holdoff_frames = 1;  // immediate recovery
+
+    agc.update(false);  // 31 + 2 = 33, but max = 32
+    assert(agc.agc_base_gain == 32);
+
+    agc.update(false);  // already at max
+    assert(agc.agc_base_gain == 32);
+}
+
+// ---------------------------------------------------------------------------
+// Test 7: Per-channel calibration offsets
+// ---------------------------------------------------------------------------
+static void test_calibration_offsets()
+{
+    ADAR1000_AGC agc;
+    agc.agc_base_gain = 30;
+    agc.min_gain = 0;
+    agc.max_gain = 60;
+
+    agc.cal_offset[0]  =  5;   // 30 + 5  = 35
+    agc.cal_offset[1]  = -10;  // 30 - 10 = 20
+    agc.cal_offset[15] =  40;  // 30 + 40 = 60 (clamped to max)
+
+    assert(agc.effectiveGain(0) == 35);
+    assert(agc.effectiveGain(1) == 20);
+    assert(agc.effectiveGain(15) == 60);  // clamped to max_gain
+
+    // Negative clamp
+    agc.cal_offset[2] = -50;   // 30 - 50 = -20, clamped to min_gain = 0
+    assert(agc.effectiveGain(2) == 0);
+
+    // Out-of-range index returns min_gain
+    assert(agc.effectiveGain(16) == agc.min_gain);
+}
+
+// ---------------------------------------------------------------------------
+// Test 8: Disabled AGC is a no-op
+// ---------------------------------------------------------------------------
+static void test_disabled_noop()
+{
+    ADAR1000_AGC agc;
+    agc.enabled = false;
+    uint8_t original = agc.agc_base_gain;
+
+    agc.update(true);   // should be ignored
+    assert(agc.agc_base_gain == original);
+    assert(agc.last_saturated == false);  // not updated when disabled
+    assert(agc.saturation_event_count == 0);
+
+    agc.update(false);  // also ignored
+    assert(agc.agc_base_gain == original);
+}
+
+// ---------------------------------------------------------------------------
+// Test 9: applyGain() produces correct SPI writes
+// ---------------------------------------------------------------------------
+static void test_apply_gain_spi()
+{
+    spy_reset();
+
+    ADAR1000Manager mgr;  // creates 4 devices
+    ADAR1000_AGC agc;
+    agc.agc_base_gain = 42;
+
+    agc.applyGain(mgr);
+
+    // Each channel: adarSetRxVgaGain -> adarWrite(gain) + adarWrite(LOAD_WORKING)
+    // Each adarWrite: CS_low (GPIO_WRITE) + SPI_TRANSMIT + CS_high (GPIO_WRITE)
+    // = 3 spy records per adarWrite
+    // = 6 spy records per channel
+    // = 16 channels * 6 = 96 total spy records
+
+    // Verify SPI transmit count: 2 SPI calls per channel * 16 channels = 32
+    int spi_count = spy_count_type(SPY_SPI_TRANSMIT);
+    assert(spi_count == 32);
+
+    // Verify GPIO write count: 4 GPIO writes per channel (CS low + CS high for each of 2 adarWrite calls)
+    int gpio_writes = spy_count_type(SPY_GPIO_WRITE);
+    assert(gpio_writes == 64);  // 16 ch * 2 adarWrite * 2 GPIO each
+}
+
+// ---------------------------------------------------------------------------
+// Test 10: resetState() clears counters but preserves config
+// ---------------------------------------------------------------------------
+static void test_reset_preserves_config()
+{
+    ADAR1000_AGC agc;
+    agc.agc_base_gain = 42;
+    agc.gain_step_down = 8;
+    agc.cal_offset[3] = -5;
+
+    // Generate some state
+    agc.update(true);
+    agc.update(true);
+    assert(agc.saturation_event_count == 2);
+    assert(agc.last_saturated == true);
+
+    agc.resetState();
+
+    // State cleared
+    assert(agc.holdoff_counter == 0);
+    assert(agc.last_saturated == false);
+    assert(agc.saturation_event_count == 0);
+
+    // Config preserved
+    assert(agc.agc_base_gain == 42 - 8 - 8);  // two saturations applied before reset
+    assert(agc.gain_step_down == 8);
+    assert(agc.cal_offset[3] == -5);
+}
+
+// ---------------------------------------------------------------------------
+// Test 11: Saturation counter increments correctly
+// ---------------------------------------------------------------------------
+static void test_saturation_counter()
+{
+    ADAR1000_AGC agc;
+
+    for (int i = 0; i < 10; ++i) {
+        agc.update(true);
+    }
+    assert(agc.saturation_event_count == 10);
+
+    // Clear frames don't increment saturation count
+    for (int i = 0; i < 5; ++i) {
+        agc.update(false);
+    }
+    assert(agc.saturation_event_count == 10);
+}
+
+// ---------------------------------------------------------------------------
+// Test 12: Mixed saturation/clear sequence
+// ---------------------------------------------------------------------------
+static void test_mixed_sequence()
+{
+    ADAR1000_AGC agc;
+    agc.agc_base_gain = 30;
+    agc.gain_step_down = 4;
+    agc.gain_step_up = 1;
+    agc.holdoff_frames = 3;
+
+    // Saturate: 30 -> 26
+    agc.update(true);
+    assert(agc.agc_base_gain == 26);
+    assert(agc.holdoff_counter == 0);
+
+    // 2 clear frames (not enough for recovery)
+    agc.update(false);
+    agc.update(false);
+    assert(agc.agc_base_gain == 26);
+    assert(agc.holdoff_counter == 2);
+
+    // Saturate again: 26 -> 22, counter resets
+    agc.update(true);
+    assert(agc.agc_base_gain == 22);
+    assert(agc.holdoff_counter == 0);
+    assert(agc.saturation_event_count == 2);
+
+    // 3 clear frames -> recovery: 22 -> 23
+    agc.update(false);
+    agc.update(false);
+    agc.update(false);
+    assert(agc.agc_base_gain == 23);
+    assert(agc.holdoff_counter == 0);
+
+    // 3 more clear -> 23 -> 24
+    agc.update(false);
+    agc.update(false);
+    agc.update(false);
+    assert(agc.agc_base_gain == 24);
+}
+
+// ---------------------------------------------------------------------------
+// Test 13: Effective gain with edge-case base_gain values
+// ---------------------------------------------------------------------------
+static void test_effective_gain_edge_cases()
+{
+    ADAR1000_AGC agc;
+    agc.min_gain = 5;
+    agc.max_gain = 250;
+
+    // Base gain at zero with positive offset
+    agc.agc_base_gain = 0;
+    agc.cal_offset[0] = 3;
+    assert(agc.effectiveGain(0) == 5);  // 0 + 3 = 3, clamped to min_gain=5
+
+    // Base gain at max with zero offset
+    agc.agc_base_gain = 250;
+    agc.cal_offset[0] = 0;
+    assert(agc.effectiveGain(0) == 250);
+
+    // Base gain at max with positive offset -> clamped
+    agc.agc_base_gain = 250;
+    agc.cal_offset[0] = 10;
+    assert(agc.effectiveGain(0) == 250);  // clamped to max_gain
+}
+
+// ---------------------------------------------------------------------------
+// main
+// ---------------------------------------------------------------------------
+int main()
+{
+    printf("=== ADAR1000_AGC Outer-Loop Unit Tests ===\n");
+
+    RUN_TEST(test_defaults);
+    RUN_TEST(test_saturation_reduces_gain);
+    RUN_TEST(test_holdoff_prevents_early_gain_up);
+    RUN_TEST(test_recovery_after_holdoff);
+    RUN_TEST(test_min_gain_clamp);
+    RUN_TEST(test_max_gain_clamp);
+    RUN_TEST(test_calibration_offsets);
+    RUN_TEST(test_disabled_noop);
+    RUN_TEST(test_apply_gain_spi);
+    RUN_TEST(test_reset_preserves_config);
+    RUN_TEST(test_saturation_counter);
+    RUN_TEST(test_mixed_sequence);
+    RUN_TEST(test_effective_gain_edge_cases);
+
+    printf("=== Results: %d/%d passed ===\n", tests_passed, tests_total);
+    return (tests_passed == tests_total) ? 0 : 1;
+}

9_Firmware/9_2_FPGA/adc_clk_mmcm.v

@@ -212,6 +212,11 @@ BUFG bufg_feedback (
 
 // ---- Output BUFG ----
 // Routes the jitter-cleaned 400 MHz CLKOUT0 onto a global clock network.
+// DONT_TOUCH prevents phys_opt_design AggressiveExplore from replicating this
+// BUFG into a cascaded chain (4 BUFGs in series observed in Build 26), which
+// added ~243ps of clock insertion delay and caused -187ps clock skew on the
+// NCO→DSP mixer critical path.
+(* DONT_TOUCH = "TRUE" *)
 BUFG bufg_clk400m (
     .I(clk_mmcm_out0),
     .O(clk_400m_out)

9_Firmware/9_2_FPGA/cic_decimator_4x_enhanced.v

@@ -66,13 +66,13 @@ reg signed [COMB_WIDTH-1:0] comb_delay [0:STAGES-1][0:COMB_DELAY-1];
 // Pipeline valid for comb stages 1-4: delayed by 1 cycle vs comb_pipe to
 // account for CREG+AREG+BREG pipeline inside comb_0_dsp (explicit DSP48E1).
 // Comb[0] result appears 1 cycle after data_valid_comb_pipe.
-(* keep = "true", max_fanout = 4 *) reg data_valid_comb_0_out;
+(* keep = "true", max_fanout = 16 *) reg data_valid_comb_0_out;
 
 // Enhanced control and monitoring
 reg [1:0] decimation_counter;
-(* keep = "true", max_fanout = 4 *) reg data_valid_delayed;
-(* keep = "true", max_fanout = 4 *) reg data_valid_comb;
-(* keep = "true", max_fanout = 4 *) reg data_valid_comb_pipe;
+(* keep = "true", max_fanout = 16 *) reg data_valid_delayed;
+(* keep = "true", max_fanout = 16 *) reg data_valid_comb;
+(* keep = "true", max_fanout = 16 *) reg data_valid_comb_pipe;
 reg [7:0] output_counter;
 reg [ACC_WIDTH-1:0] max_integrator_value;
 reg overflow_detected;

9_Firmware/9_2_FPGA/constraints/adc_clk_mmcm.xdc

@@ -83,3 +83,13 @@ set_false_path -through [get_pins rx_inst/adc/mmcm_inst/mmcm_adc_400m/LOCKED]
 # Waiving hold on these 8 paths (adc_d_p[0..7] → IDDR) is standard practice
 # for source-synchronous LVDS ADC interfaces using BUFIO capture.
 set_false_path -hold -from [get_ports {adc_d_p[*]}] -to [get_clocks adc_dco_p]
+
+# --------------------------------------------------------------------------
+# Timing margin for 400 MHz critical paths
+# --------------------------------------------------------------------------
+# Extra setup uncertainty forces Vivado to leave margin for temperature/voltage/
+# aging variation. Reduced from 200 ps to 100 ps after NCO→mixer pipeline
+# register fix eliminated the dominant timing bottleneck (WNS went from +0.002ns
+# to comfortable margin). 100 ps still provides ~4% guardband on the 2.5ns period.
+# This is additive to the existing jitter-based uncertainty (~53 ps).
+set_clock_uncertainty -setup -add 0.100 [get_clocks clk_mmcm_out0]

9_Firmware/9_2_FPGA/constraints/xc7a50t_ftg256.xdc

@@ -222,8 +222,16 @@ set_property IOSTANDARD LVCMOS33 [get_ports {stm32_new_*}]
 set_property IOSTANDARD LVCMOS33 [get_ports {stm32_mixers_enable}]
 # reset_n is DIG_4 (PD12) — constrained above in the RESET section
 
-# DIG_5 = H11, DIG_6 = G12, DIG_7 = H12 — available for FPGA→STM32 status
-# Currently unused in RTL. Could be connected to status outputs if needed.
+# DIG_5 = H11, DIG_6 = G12, DIG_7 = H12 — FPGA→STM32 status outputs
+# DIG_5: AGC saturation flag (PD13 on STM32)
+# DIG_6: reserved (PD14)
+# DIG_7: reserved (PD15)
+set_property PACKAGE_PIN H11 [get_ports {gpio_dig5}]
+set_property PACKAGE_PIN G12 [get_ports {gpio_dig6}]
+set_property PACKAGE_PIN H12 [get_ports {gpio_dig7}]
+set_property IOSTANDARD LVCMOS33 [get_ports {gpio_dig*}]
+set_property DRIVE 8 [get_ports {gpio_dig*}]
+set_property SLEW SLOW [get_ports {gpio_dig*}]
 
 # ============================================================================
 # ADC INTERFACE (LVDS — Bank 14, VCCO=3.3V)

9_Firmware/9_2_FPGA/ddc_400m.v

@@ -102,14 +102,19 @@ wire signed [17:0] debug_mixed_q_trunc;
 reg [7:0] signal_power_i, signal_power_q;
 
 // Internal mixing signals
-// DSP48E1 with AREG=1, BREG=1, MREG=1, PREG=1 handles all internal pipelining
-// Latency: 4 cycles (1 for AREG/BREG, 1 for MREG, 1 for PREG, 1 for post-DSP retiming)
+// Pipeline: NCO fabric reg (1) + DSP48E1 AREG/BREG (1) + MREG (1) + PREG (1) + retiming (1) = 5 cycles
+// The NCO fabric pipeline register was added to break the long NCO→DSP B-port route
+// (1.505ns routing in Build 26, WNS=+0.002ns). With BREG=1 still active inside the DSP,
+// total latency increases by 1 cycle (2.5ns at 400MHz — negligible for radar).
 wire signed [MIXER_WIDTH-1:0] adc_signed_w;
 reg signed [MIXER_WIDTH + NCO_WIDTH -1:0] mixed_i, mixed_q;
 reg mixed_valid;
 reg mixer_overflow_i, mixer_overflow_q;
-// Pipeline valid tracking: 4-stage shift register (3 for DSP48E1 + 1 for post-DSP retiming)
-reg [3:0] dsp_valid_pipe;
+// Pipeline valid tracking: 5-stage shift register (1 NCO pipe + 3 DSP48E1 + 1 retiming)
+reg [4:0] dsp_valid_pipe;
+// NCO→DSP pipeline registers — breaks the long NCO sin/cos → DSP48E1 B-port route
+// DONT_TOUCH prevents Vivado from absorbing these into the DSP or optimizing away
+(* DONT_TOUCH = "TRUE" *) reg signed [15:0] cos_nco_pipe, sin_nco_pipe;
 // Post-DSP retiming registers — breaks DSP48E1 CLK→P to fabric timing path
 // This extra pipeline stage absorbs the 1.866ns DSP output prop delay + routing,
 // ensuring WNS > 0 at 400 MHz regardless of placement seed
@@ -210,11 +215,11 @@ nco_400m_enhanced nco_core (
 //
 // Architecture:
 //   ADC data → sign-extend to 18b → DSP48E1 A-port (AREG=1 pipelines it)
-//   NCO cos/sin → sign-extend to 18b → DSP48E1 B-port (BREG=1 pipelines it)
+//   NCO cos/sin → fabric pipeline reg → DSP48E1 B-port (BREG=1 pipelines it)
 //   Multiply result captured by MREG=1, then output registered by PREG=1
 //   force_saturation override applied AFTER DSP48E1 output (not on input path)
 //
-// Latency: 3 clock cycles (AREG/BREG + MREG + PREG)
+// Latency: 4 clock cycles (1 NCO pipe + 1 AREG/BREG + 1 MREG + 1 PREG) + 1 retiming = 5 total
 // PREG=1 absorbs DSP48E1 CLK→P delay internally, preventing fabric timing violations
 // In simulation (Icarus), uses behavioral equivalent since DSP48E1 is Xilinx-only
 // ============================================================================
@@ -223,24 +228,35 @@ nco_400m_enhanced nco_core (
 assign adc_signed_w = {1'b0, adc_data, {(MIXER_WIDTH-ADC_WIDTH-1){1'b0}}} - 
                       {1'b0, {ADC_WIDTH{1'b1}}, {(MIXER_WIDTH-ADC_WIDTH-1){1'b0}}} / 2;
 
-// Valid pipeline: 4-stage shift register (3 for DSP48E1 AREG+MREG+PREG + 1 for retiming)
+// Valid pipeline: 5-stage shift register (1 NCO pipe + 3 DSP48E1 AREG+MREG+PREG + 1 retiming)
 always @(posedge clk_400m or negedge reset_n_400m) begin
     if (!reset_n_400m) begin
-        dsp_valid_pipe <= 4'b0000;
+        dsp_valid_pipe <= 5'b00000;
     end else begin
-        dsp_valid_pipe <= {dsp_valid_pipe[2:0], (nco_ready && adc_data_valid_i && adc_data_valid_q)};
+        dsp_valid_pipe <= {dsp_valid_pipe[3:0], (nco_ready && adc_data_valid_i && adc_data_valid_q)};
     end
 end
 
 `ifdef SIMULATION
 // ---- Behavioral model for Icarus Verilog simulation ----
-// Mimics DSP48E1 with AREG=1, BREG=1, MREG=1, PREG=1 (3-cycle latency)
+// Mimics NCO pipeline + DSP48E1 with AREG=1, BREG=1, MREG=1, PREG=1 (4-cycle DSP + 1 NCO pipe)
 reg signed [MIXER_WIDTH-1:0] adc_signed_reg;     // Models AREG
 reg signed [15:0] cos_pipe_reg, sin_pipe_reg;     // Models BREG
 reg signed [MIXER_WIDTH+NCO_WIDTH-1:0] mult_i_internal, mult_q_internal;  // Models MREG
 reg signed [MIXER_WIDTH+NCO_WIDTH-1:0] mult_i_reg, mult_q_reg;            // Models PREG
 
-// Stage 1: AREG/BREG equivalent
+// Stage 0: NCO pipeline — breaks long NCO→DSP route (matches synthesis fabric registers)
+always @(posedge clk_400m or negedge reset_n_400m) begin
+    if (!reset_n_400m) begin
+        cos_nco_pipe <= 0;
+        sin_nco_pipe <= 0;
+    end else begin
+        cos_nco_pipe <= cos_out;
+        sin_nco_pipe <= sin_out;
+    end
+end
+
+// Stage 1: AREG/BREG equivalent (uses pipelined NCO outputs)
 always @(posedge clk_400m or negedge reset_n_400m) begin
     if (!reset_n_400m) begin
         adc_signed_reg <= 0;
@@ -248,8 +264,8 @@ always @(posedge clk_400m or negedge reset_n_400m) begin
         sin_pipe_reg <= 0;
     end else begin
         adc_signed_reg <= adc_signed_w;
-        cos_pipe_reg <= cos_out;
-        sin_pipe_reg <= sin_out;
+        cos_pipe_reg <= cos_nco_pipe;
+        sin_pipe_reg <= sin_nco_pipe;
     end
 end
 
@@ -291,6 +307,20 @@ end
 // This guarantees AREG/BREG/MREG are used, achieving timing closure at 400 MHz
 wire [47:0] dsp_p_i, dsp_p_q;
 
+// NCO pipeline stage — breaks the long NCO sin/cos → DSP48E1 B-port route
+// (1.505ns routing observed in Build 26). These fabric registers are placed
+// near the DSP by the placer, splitting the route into two shorter segments.
+// DONT_TOUCH on the reg declaration (above) prevents absorption/retiming.
+always @(posedge clk_400m or negedge reset_n_400m) begin
+    if (!reset_n_400m) begin
+        cos_nco_pipe <= 0;
+        sin_nco_pipe <= 0;
+    end else begin
+        cos_nco_pipe <= cos_out;
+        sin_nco_pipe <= sin_out;
+    end
+end
+
 // DSP48E1 for I-channel mixer (adc_signed * cos_out)
 DSP48E1 #(
     // Feature control attributes
@@ -350,7 +380,7 @@ DSP48E1 #(
     .CEINMODE(1'b0),
     // Data ports
     .A({{12{adc_signed_w[MIXER_WIDTH-1]}}, adc_signed_w}),   // Sign-extend 18b to 30b
-    .B({{2{cos_out[15]}}, cos_out}),                          // Sign-extend 16b to 18b
+    .B({{2{cos_nco_pipe[15]}}, cos_nco_pipe}),                // Sign-extend 16b to 18b (pipelined)
     .C(48'b0),
     .D(25'b0),
     .CARRYIN(1'b0),
@@ -432,7 +462,7 @@ DSP48E1 #(
     .CED(1'b0),
     .CEINMODE(1'b0),
     .A({{12{adc_signed_w[MIXER_WIDTH-1]}}, adc_signed_w}),
-    .B({{2{sin_out[15]}}, sin_out}),
+    .B({{2{sin_nco_pipe[15]}}, sin_nco_pipe}),
     .C(48'b0),
     .D(25'b0),
     .CARRYIN(1'b0),
@@ -492,7 +522,7 @@ always @(posedge clk_400m or negedge reset_n_400m) begin
         mixer_overflow_q <= 0;
         saturation_count <= 0;
         overflow_detected <= 0;
-    end else if (dsp_valid_pipe[3]) begin
+    end else if (dsp_valid_pipe[4]) begin
         // Force saturation for testing (applied after DSP output, not on input path)
         if (force_saturation_sync) begin
             mixed_i <= 34'h1FFFFFFFF;

9_Firmware/9_2_FPGA/fpga_self_test.v

@@ -296,7 +296,7 @@ always @(posedge clk or negedge reset_n) begin
                     state           <= ST_DONE;
                 end
             end
-            // Timeout: if no ADC data after 10000 cycles, FAIL
+            // Timeout: if no ADC data after 1000 cycles (10 us @ 100 MHz), FAIL
             step_cnt <= step_cnt + 1;
             if (step_cnt >= 10'd1000 && adc_cap_cnt == 0) begin
                 result_flags[4] <= 1'b0;

9_Firmware/9_2_FPGA/radar_receiver_final.v

@@ -42,6 +42,13 @@ module radar_receiver_final (
     // [2:0]=shift amount: 0..7 bits. Default 0 = pass-through.
     input wire [3:0] host_gain_shift,
 
+    // AGC configuration (opcodes 0x28-0x2C, active only when agc_enable=1)
+    input wire        host_agc_enable,      // 0x28: 0=manual, 1=auto AGC
+    input wire [7:0]  host_agc_target,      // 0x29: target peak magnitude
+    input wire [3:0]  host_agc_attack,      // 0x2A: gain-down step on clipping
+    input wire [3:0]  host_agc_decay,       // 0x2B: gain-up step when weak
+    input wire [3:0]  host_agc_holdoff,     // 0x2C: frames before gain-up
+
     // STM32 toggle signals for mode 00 (STM32-driven) pass-through.
     // These are CDC-synchronized in radar_system_top.v / radar_transmitter.v
     // before reaching this module. In mode 00, the RX mode controller uses
@@ -60,7 +67,12 @@ module radar_receiver_final (
     // ADC raw data tap (clk_100m domain, post-DDC, for self-test / debug)
     output wire [15:0] dbg_adc_i,            // DDC output I (16-bit signed, 100 MHz)
     output wire [15:0] dbg_adc_q,            // DDC output Q (16-bit signed, 100 MHz)
-    output wire        dbg_adc_valid         // DDC output valid (100 MHz)
+    output wire        dbg_adc_valid,        // DDC output valid (100 MHz)
+
+    // AGC status outputs (for status readback / STM32 outer loop)
+    output wire [7:0]  agc_saturation_count, // Per-frame clipped sample count
+    output wire [7:0]  agc_peak_magnitude,   // Per-frame peak (upper 8 bits)
+    output wire [3:0]  agc_current_gain      // Effective gain_shift encoding
 );
 
 // ========== INTERNAL SIGNALS ==========
@@ -86,7 +98,9 @@ wire adc_valid_sync;
 // Gain-controlled signals (between DDC output and matched filter)
 wire signed [15:0] gc_i, gc_q;
 wire gc_valid;
-wire [7:0] gc_saturation_count;  // Diagnostic: clipped sample counter
+wire [7:0] gc_saturation_count;  // Diagnostic: per-frame clipped sample counter
+wire [7:0] gc_peak_magnitude;    // Diagnostic: per-frame peak magnitude
+wire [3:0] gc_current_gain;      // Diagnostic: effective gain_shift
 
 // Reference signals for the processing chain
 wire [15:0] long_chirp_real, long_chirp_imag;
@@ -160,7 +174,7 @@ wire clk_400m;
 // the buffered 400MHz DCO clock via adc_dco_bufg, avoiding duplicate
 // IBUFDS instantiations on the same LVDS clock pair.
 
-// 1. ADC + CDC + AGC
+// 1. ADC + CDC + Digital Gain
 
 // CMOS Output Interface (400MHz Domain)
 wire [7:0] adc_data_cmos;  // 8-bit ADC data (CMOS, from ad9484_interface_400m)
@@ -222,9 +236,10 @@ ddc_input_interface ddc_if (
     .data_sync_error()
 );
 
-// 2b. Digital Gain Control (Fix 3)
+// 2b. Digital Gain Control with AGC
 // Host-configurable power-of-2 shift between DDC output and matched filter.
-// Default gain_shift=0 → pass-through (no behavioral change from baseline).
+// Default gain_shift=0, agc_enable=0 → pass-through (no behavioral change).
+// When agc_enable=1: auto-adjusts gain per frame based on peak/saturation.
 rx_gain_control gain_ctrl (
     .clk(clk),
     .reset_n(reset_n),
@@ -232,10 +247,21 @@ rx_gain_control gain_ctrl (
     .data_q_in(adc_q_scaled),
     .valid_in(adc_valid_sync),
     .gain_shift(host_gain_shift),
+    // AGC configuration
+    .agc_enable(host_agc_enable),
+    .agc_target(host_agc_target),
+    .agc_attack(host_agc_attack),
+    .agc_decay(host_agc_decay),
+    .agc_holdoff(host_agc_holdoff),
+    // Frame boundary from Doppler processor
+    .frame_boundary(doppler_frame_done),
+    // Outputs
     .data_i_out(gc_i),
     .data_q_out(gc_q),
     .valid_out(gc_valid),
-    .saturation_count(gc_saturation_count)
+    .saturation_count(gc_saturation_count),
+    .peak_magnitude(gc_peak_magnitude),
+    .current_gain(gc_current_gain)
 );
 
 // 3. Dual Chirp Memory Loader
@@ -474,4 +500,9 @@ assign dbg_adc_i     = adc_i_scaled;
 assign dbg_adc_q     = adc_q_scaled;
 assign dbg_adc_valid = adc_valid_sync;
 
+// ========== AGC STATUS OUTPUTS ==========
+assign agc_saturation_count = gc_saturation_count;
+assign agc_peak_magnitude   = gc_peak_magnitude;
+assign agc_current_gain     = gc_current_gain;
+
 endmodule

9_Firmware/9_2_FPGA/radar_system_top.v

@@ -125,7 +125,13 @@ module radar_system_top (
     output wire [5:0] dbg_range_bin,
     
     // System status
-    output wire [3:0] system_status
+    output wire [3:0] system_status,
+
+    // FPGA→STM32 GPIO outputs (DIG_5..DIG_7 on 50T board)
+    // Used by STM32 outer AGC loop to read saturation state without USB polling.
+    output wire gpio_dig5,          // DIG_5 (H11→PD13): AGC saturation flag (1=clipping detected)
+    output wire gpio_dig6,          // DIG_6 (G12→PD14): reserved (tied low)
+    output wire gpio_dig7           // DIG_7 (H12→PD15): reserved (tied low)
 );
 
 // ============================================================================
@@ -187,6 +193,11 @@ wire [15:0] rx_dbg_adc_i;
 wire [15:0] rx_dbg_adc_q;
 wire        rx_dbg_adc_valid;
 
+// AGC status from receiver (for status readback and GPIO)
+wire [7:0]  rx_agc_saturation_count;
+wire [7:0]  rx_agc_peak_magnitude;
+wire [3:0]  rx_agc_current_gain;
+
 // Data packing for USB
 wire [31:0] usb_range_profile;
 wire usb_range_valid;
@@ -259,6 +270,13 @@ reg        host_cfar_enable;      // Opcode 0x25: 1=CFAR, 0=simple threshold
 reg        host_mti_enable;       // Opcode 0x26: 1=MTI active, 0=pass-through
 reg [2:0]  host_dc_notch_width;   // Opcode 0x27: DC notch ±width bins (0=off, 1..7)
 
+// AGC configuration registers (host-configurable via USB, opcodes 0x28-0x2C)
+reg        host_agc_enable;       // Opcode 0x28: 0=manual gain, 1=auto AGC
+reg [7:0]  host_agc_target;       // Opcode 0x29: target peak magnitude (default 200)
+reg [3:0]  host_agc_attack;       // Opcode 0x2A: gain-down step on clipping (default 1)
+reg [3:0]  host_agc_decay;        // Opcode 0x2B: gain-up step when weak (default 1)
+reg [3:0]  host_agc_holdoff;      // Opcode 0x2C: frames to wait before gain-up (default 4)
+
 // Board bring-up self-test registers (opcode 0x30 trigger, 0x31 readback)
 reg        host_self_test_trigger;  // Opcode 0x30: self-clearing pulse
 wire       self_test_busy;
@@ -518,6 +536,12 @@ radar_receiver_final rx_inst (
     .host_chirps_per_elev(host_chirps_per_elev),
     // Fix 3: digital gain control
     .host_gain_shift(host_gain_shift),
+    // AGC configuration (opcodes 0x28-0x2C)
+    .host_agc_enable(host_agc_enable),
+    .host_agc_target(host_agc_target),
+    .host_agc_attack(host_agc_attack),
+    .host_agc_decay(host_agc_decay),
+    .host_agc_holdoff(host_agc_holdoff),
     // STM32 toggle signals for RX mode controller (mode 00 pass-through).
     // These are the raw GPIO inputs — the RX mode controller's edge detectors
     // (inside radar_mode_controller) handle debouncing/edge detection.
@@ -532,7 +556,11 @@ radar_receiver_final rx_inst (
     // ADC debug tap (for self-test / bring-up)
     .dbg_adc_i(rx_dbg_adc_i),
     .dbg_adc_q(rx_dbg_adc_q),
-    .dbg_adc_valid(rx_dbg_adc_valid)
+    .dbg_adc_valid(rx_dbg_adc_valid),
+    // AGC status outputs
+    .agc_saturation_count(rx_agc_saturation_count),
+    .agc_peak_magnitude(rx_agc_peak_magnitude),
+    .agc_current_gain(rx_agc_current_gain)
 );
 
 // ============================================================================
@@ -744,7 +772,13 @@ if (USB_MODE == 0) begin : gen_ft601
         // Self-test status readback
         .status_self_test_flags(self_test_flags_latched),
         .status_self_test_detail(self_test_detail_latched),
-        .status_self_test_busy(self_test_busy)
+        .status_self_test_busy(self_test_busy),
+
+        // AGC status readback
+        .status_agc_current_gain(rx_agc_current_gain),
+        .status_agc_peak_magnitude(rx_agc_peak_magnitude),
+        .status_agc_saturation_count(rx_agc_saturation_count),
+        .status_agc_enable(host_agc_enable)
     );
 
     // FT2232H ports unused in FT601 mode — tie off
@@ -805,7 +839,13 @@ end else begin : gen_ft2232h
         // Self-test status readback
         .status_self_test_flags(self_test_flags_latched),
         .status_self_test_detail(self_test_detail_latched),
-        .status_self_test_busy(self_test_busy)
+        .status_self_test_busy(self_test_busy),
+
+        // AGC status readback
+        .status_agc_current_gain(rx_agc_current_gain),
+        .status_agc_peak_magnitude(rx_agc_peak_magnitude),
+        .status_agc_saturation_count(rx_agc_saturation_count),
+        .status_agc_enable(host_agc_enable)
     );
 
     // FT601 ports unused in FT2232H mode — tie off
@@ -892,6 +932,12 @@ always @(posedge clk_100m_buf or negedge sys_reset_n) begin
         // Ground clutter removal defaults (disabled — backward-compatible)
         host_mti_enable         <= 1'b0;      // MTI off
         host_dc_notch_width     <= 3'd0;      // DC notch off
+        // AGC defaults (disabled — backward-compatible with manual gain)
+        host_agc_enable         <= 1'b0;      // AGC off (manual gain)
+        host_agc_target         <= 8'd200;    // Target peak magnitude
+        host_agc_attack         <= 4'd1;      // 1-step gain-down on clipping
+        host_agc_decay          <= 4'd1;      // 1-step gain-up when weak
+        host_agc_holdoff        <= 4'd4;      // 4 frames before gain-up
         // Self-test defaults
         host_self_test_trigger  <= 1'b0;      // Self-test idle
     end else begin
@@ -936,6 +982,12 @@ always @(posedge clk_100m_buf or negedge sys_reset_n) begin
                 // Ground clutter removal opcodes
                 8'h26: host_mti_enable         <= usb_cmd_value[0];
                 8'h27: host_dc_notch_width     <= usb_cmd_value[2:0];
+                // AGC configuration opcodes
+                8'h28: host_agc_enable         <= usb_cmd_value[0];
+                8'h29: host_agc_target         <= usb_cmd_value[7:0];
+                8'h2A: host_agc_attack         <= usb_cmd_value[3:0];
+                8'h2B: host_agc_decay          <= usb_cmd_value[3:0];
+                8'h2C: host_agc_holdoff        <= usb_cmd_value[3:0];
                 // Board bring-up self-test opcodes
                 8'h30: host_self_test_trigger  <= 1'b1;  // Trigger self-test
                 8'h31: host_status_request     <= 1'b1;  // Self-test readback (status alias)
@@ -978,6 +1030,16 @@ end
 
 assign system_status = status_reg;
 
+// ============================================================================
+// FPGA→STM32 GPIO OUTPUTS (DIG_5, DIG_6, DIG_7)
+// ============================================================================
+// DIG_5: AGC saturation flag — high when per-frame saturation_count > 0.
+//        STM32 reads PD13 to detect clipping and adjust ADAR1000 VGA gain.
+// DIG_6, DIG_7: Reserved (tied low for future use).
+assign gpio_dig5 = (rx_agc_saturation_count != 8'd0);
+assign gpio_dig6 = 1'b0;
+assign gpio_dig7 = 1'b0;
+
 // ============================================================================
 // DEBUG AND VERIFICATION
 // ============================================================================

9_Firmware/9_2_FPGA/radar_system_top_50t.v

@@ -76,7 +76,12 @@ module radar_system_top_50t (
     output wire ft_rd_n,              // Read strobe (active low)
     output wire ft_wr_n,              // Write strobe (active low)
     output wire ft_oe_n,              // Output enable / bus direction
-    output wire ft_siwu               // Send Immediate / WakeUp
+    output wire ft_siwu,              // Send Immediate / WakeUp
+
+    // ===== FPGA→STM32 GPIO (Bank 15: 3.3V) =====
+    output wire gpio_dig5,            // DIG_5 (H11→PD13): AGC saturation flag
+    output wire gpio_dig6,            // DIG_6 (G12→PD14): reserved
+    output wire gpio_dig7             // DIG_7 (H12→PD15): reserved
 );
 
     // ===== Tie-off wires for unconstrained FT601 inputs (inactive with USB_MODE=1) =====
@@ -207,7 +212,12 @@ module radar_system_top_50t (
         .dbg_doppler_valid      (dbg_doppler_valid_nc),
         .dbg_doppler_bin        (dbg_doppler_bin_nc),
         .dbg_range_bin          (dbg_range_bin_nc),
-        .system_status          (system_status_nc)
+        .system_status          (system_status_nc),
+
+        // ----- FPGA→STM32 GPIO (DIG_5..DIG_7) -----
+        .gpio_dig5              (gpio_dig5),
+        .gpio_dig6              (gpio_dig6),
+        .gpio_dig7              (gpio_dig7)
     );
 
 endmodule

9_Firmware/9_2_FPGA/rx_gain_control.v

@@ -3,19 +3,32 @@
 /**
  * rx_gain_control.v
  *
- * Host-configurable digital gain control for the receive path.
- * Placed between DDC output (ddc_input_interface) and matched filter input.
+ * Digital gain control with optional per-frame automatic gain control (AGC)
+ * for the receive path. Placed between DDC output and matched filter input.
  *
- * Features:
- *   - Bidirectional power-of-2 gain shift (arithmetic shift)
+ * Manual mode (agc_enable=0):
+ *   - Uses host_gain_shift directly (backward-compatible, no behavioral change)
  *   - gain_shift[3]   = direction: 0 = left shift (amplify), 1 = right shift (attenuate)
  *   - gain_shift[2:0] = amount: 0..7 bits
- *   - Symmetric saturation to ±32767 on overflow (left shift only)
- *   - Saturation counter: 8-bit, counts samples that clipped (wraps at 255)
- *   - 1-cycle latency, valid-in/valid-out pipeline
- *   - Zero-overhead pass-through when gain_shift == 0
+ *   - Symmetric saturation to ±32767 on overflow
  *
- * Intended insertion point in radar_receiver_final.v:
+ * AGC mode (agc_enable=1):
+ *   - Per-frame automatic gain adjustment based on peak/saturation metrics
+ *   - Internal signed gain: -7 (max attenuation) to +7 (max amplification)
+ *   - On frame_boundary:
+ *       * If saturation detected: gain -= agc_attack (fast, immediate)
+ *       * Else if peak < target after holdoff frames: gain += agc_decay (slow)
+ *       * Else: hold current gain
+ *   - host_gain_shift serves as initial gain when AGC first enabled
+ *
+ * Status outputs (for readback via status_words):
+ *   - current_gain[3:0]: effective gain_shift encoding (manual or AGC)
+ *   - peak_magnitude[7:0]: per-frame peak |sample| (upper 8 bits of 15-bit value)
+ *   - saturation_count[7:0]: per-frame clipped sample count (capped at 255)
+ *
+ * Timing: 1-cycle data latency, valid-in/valid-out pipeline.
+ *
+ * Insertion point in radar_receiver_final.v:
  *   ddc_input_interface → rx_gain_control → matched_filter_multi_segment
  */
 
@@ -28,27 +41,75 @@ module rx_gain_control (
     input  wire signed [15:0] data_q_in,
     input  wire               valid_in,
 
-    // Gain configuration (from host via USB command)
-    // [3]   = direction: 0=amplify (left shift), 1=attenuate (right shift)
-    // [2:0] = shift amount: 0..7 bits
+    // Host gain configuration (from USB command opcode 0x16)
+    // [3]=direction: 0=amplify (left shift), 1=attenuate (right shift)
+    // [2:0]=shift amount: 0..7 bits. Default 0x00 = pass-through.
+    // In AGC mode: serves as initial gain on AGC enable transition.
     input  wire [3:0]  gain_shift,
 
+    // AGC configuration inputs (from host via USB, opcodes 0x28-0x2C)
+    input  wire        agc_enable,     // 0x28: 0=manual gain, 1=auto AGC
+    input  wire [7:0]  agc_target,     // 0x29: target peak magnitude (unsigned, default 200)
+    input  wire [3:0]  agc_attack,     // 0x2A: attenuation step on clipping (default 1)
+    input  wire [3:0]  agc_decay,      // 0x2B: amplification step when weak (default 1)
+    input  wire [3:0]  agc_holdoff,    // 0x2C: frames to wait before gain-up (default 4)
+
+    // Frame boundary pulse (1 clk cycle, from Doppler frame_complete)
+    input  wire        frame_boundary,
+
     // Data output (to matched filter)
     output reg  signed [15:0] data_i_out,
     output reg  signed [15:0] data_q_out,
     output reg                valid_out,
 
-    // Diagnostics
-    output reg  [7:0]  saturation_count  // Number of clipped samples (wraps at 255)
+    // Diagnostics / status readback
+    output reg  [7:0]  saturation_count,  // Per-frame clipped sample count (capped at 255)
+    output reg  [7:0]  peak_magnitude,    // Per-frame peak |sample| (upper 8 bits of 15-bit)
+    output reg  [3:0]  current_gain       // Current effective gain_shift (for status readback)
 );
 
-// Decompose gain_shift
-wire       shift_right = gain_shift[3];
-wire [2:0] shift_amt   = gain_shift[2:0];
+// =========================================================================
+// INTERNAL AGC STATE
+// =========================================================================
 
-// -------------------------------------------------------------------------
-// Combinational shift + saturation
-// -------------------------------------------------------------------------
+// Signed internal gain: -7 (max attenuation) to +7 (max amplification)
+// Stored as 4-bit signed (range -8..+7, clamped to -7..+7)
+reg signed [3:0] agc_gain;
+
+// Holdoff counter: counts frames without saturation before allowing gain-up
+reg [3:0] holdoff_counter;
+
+// Per-frame accumulators (running, reset on frame_boundary)
+reg [7:0]  frame_sat_count;    // Clipped samples this frame
+reg [14:0] frame_peak;         // Peak |sample| this frame (15-bit unsigned)
+
+// Previous AGC enable state (for detecting 0→1 transition)
+reg agc_enable_prev;
+
+// Combinational helpers for inclusive frame-boundary snapshot
+// (used when valid_in and frame_boundary coincide)
+reg wire_frame_sat_incr;
+reg wire_frame_peak_update;
+
+// =========================================================================
+// EFFECTIVE GAIN SELECTION
+// =========================================================================
+
+// Convert between signed internal gain and the gain_shift[3:0] encoding.
+//   gain_shift[3]=0, [2:0]=N → amplify by N bits (internal gain = +N)
+//   gain_shift[3]=1, [2:0]=N → attenuate by N bits (internal gain = -N)
+
+// Effective gain_shift used for the actual shift operation
+wire [3:0] effective_gain;
+assign effective_gain = agc_enable ? current_gain : gain_shift;
+
+// Decompose effective gain for shift logic
+wire       shift_right = effective_gain[3];
+wire [2:0] shift_amt   = effective_gain[2:0];
+
+// =========================================================================
+// COMBINATIONAL SHIFT + SATURATION
+// =========================================================================
 // Use wider intermediates to detect overflow on left shift.
 // 24 bits is enough: 16 + 7 shift = 23 significant bits max.
 
@@ -69,26 +130,153 @@ wire signed [15:0] sat_i = overflow_i ? (shifted_i[23] ? -16'sd32768 : 16'sd3276
 wire signed [15:0] sat_q = overflow_q ? (shifted_q[23] ? -16'sd32768 : 16'sd32767)
                                       : shifted_q[15:0];
 
-// -------------------------------------------------------------------------
-// Registered output stage (1-cycle latency)
-// -------------------------------------------------------------------------
+// =========================================================================
+// PEAK MAGNITUDE TRACKING (combinational)
+// =========================================================================
+// Absolute value of signed 16-bit: flip sign bit if negative.
+// Result is 15-bit unsigned [0, 32767]. (We ignore -32768 → 32767 edge case.)
+wire [14:0] abs_i = data_i_in[15] ? (~data_i_in[14:0] + 15'd1) : data_i_in[14:0];
+wire [14:0] abs_q = data_q_in[15] ? (~data_q_in[14:0] + 15'd1) : data_q_in[14:0];
+wire [14:0] max_iq = (abs_i > abs_q) ? abs_i : abs_q;
+
+// =========================================================================
+// SIGNED GAIN ↔ GAIN_SHIFT ENCODING CONVERSION
+// =========================================================================
+// Convert signed agc_gain to gain_shift[3:0] encoding
+function [3:0] signed_to_encoding;
+    input signed [3:0] g;
+    begin
+        if (g >= 0)
+            signed_to_encoding = {1'b0, g[2:0]};       // amplify
+        else
+            signed_to_encoding = {1'b1, (~g[2:0]) + 3'd1}; // attenuate: -g
+    end
+endfunction
+
+// Convert gain_shift[3:0] encoding to signed gain
+function signed [3:0] encoding_to_signed;
+    input [3:0] enc;
+    begin
+        if (enc[3] == 1'b0)
+            encoding_to_signed = {1'b0, enc[2:0]};     // +0..+7
+        else
+            encoding_to_signed = -$signed({1'b0, enc[2:0]}); // -1..-7
+    end
+endfunction
+
+// =========================================================================
+// CLAMPING HELPER
+// =========================================================================
+// Clamp a wider signed value to [-7, +7]
+function signed [3:0] clamp_gain;
+    input signed [4:0] val;  // 5-bit to handle overflow from add
+    begin
+        if (val > 5'sd7)
+            clamp_gain = 4'sd7;
+        else if (val < -5'sd7)
+            clamp_gain = -4'sd7;
+        else
+            clamp_gain = val[3:0];
+    end
+endfunction
+
+// =========================================================================
+// REGISTERED OUTPUT + AGC STATE MACHINE
+// =========================================================================
 always @(posedge clk or negedge reset_n) begin
     if (!reset_n) begin
+        // Data path
         data_i_out       <= 16'sd0;
         data_q_out       <= 16'sd0;
         valid_out        <= 1'b0;
+        // Status outputs
         saturation_count <= 8'd0;
+        peak_magnitude   <= 8'd0;
+        current_gain     <= 4'd0;
+        // AGC internal state
+        agc_gain         <= 4'sd0;
+        holdoff_counter  <= 4'd0;
+        frame_sat_count  <= 8'd0;
+        frame_peak       <= 15'd0;
+        agc_enable_prev  <= 1'b0;
     end else begin
-        valid_out <= valid_in;
+        // Track AGC enable transitions
+        agc_enable_prev <= agc_enable;
 
+        // Compute inclusive metrics: if valid_in fires this cycle,
+        // include current sample in the snapshot taken at frame_boundary.
+        // This avoids losing the last sample when valid_in and
+        // frame_boundary coincide (NBA last-write-wins would otherwise
+        // snapshot stale values then reset, dropping the sample entirely).
+        wire_frame_sat_incr = (valid_in && (overflow_i || overflow_q)
+                               && (frame_sat_count != 8'hFF));
+        wire_frame_peak_update = (valid_in && (max_iq > frame_peak));
+
+        // ---- Data pipeline (1-cycle latency) ----
+        valid_out <= valid_in;
         if (valid_in) begin
             data_i_out <= sat_i;
             data_q_out <= sat_q;
 
-            // Count clipped samples (either channel clipping counts as 1)
-            if ((overflow_i || overflow_q) && (saturation_count != 8'hFF))
-                saturation_count <= saturation_count + 8'd1;
+            // Per-frame saturation counting
+            if ((overflow_i || overflow_q) && (frame_sat_count != 8'hFF))
+                frame_sat_count <= frame_sat_count + 8'd1;
+
+            // Per-frame peak tracking (pre-gain, measures input signal level)
+            if (max_iq > frame_peak)
+                frame_peak <= max_iq;
         end
+
+        // ---- Frame boundary: AGC update + metric snapshot ----
+        if (frame_boundary) begin
+            // Snapshot per-frame metrics INCLUDING current sample if valid_in
+            saturation_count <= wire_frame_sat_incr
+                                ? (frame_sat_count + 8'd1)
+                                : frame_sat_count;
+            peak_magnitude   <= wire_frame_peak_update
+                                ? max_iq[14:7]
+                                : frame_peak[14:7];
+
+            // Reset per-frame accumulators for next frame
+            frame_sat_count <= 8'd0;
+            frame_peak      <= 15'd0;
+
+            if (agc_enable) begin
+                // AGC auto-adjustment at frame boundary
+                // Use inclusive counts/peaks (accounting for simultaneous valid_in)
+                if (wire_frame_sat_incr || frame_sat_count > 8'd0) begin
+                    // Clipping detected: reduce gain immediately (attack)
+                    agc_gain <= clamp_gain($signed({agc_gain[3], agc_gain}) -
+                                           $signed({1'b0, agc_attack}));
+                    holdoff_counter <= agc_holdoff;  // Reset holdoff
+                end else if ((wire_frame_peak_update ? max_iq[14:7] : frame_peak[14:7])
+                             < agc_target) begin
+                    // Signal too weak: increase gain after holdoff expires
+                    if (holdoff_counter == 4'd0) begin
+                        agc_gain <= clamp_gain($signed({agc_gain[3], agc_gain}) +
+                                               $signed({1'b0, agc_decay}));
+                    end else begin
+                        holdoff_counter <= holdoff_counter - 4'd1;
+                    end
+                end else begin
+                    // Signal in good range, no saturation: hold gain
+                    // Reset holdoff so next weak frame has to wait again
+                    holdoff_counter <= agc_holdoff;
+                end
+            end
+        end
+
+        // ---- AGC enable transition: initialize from host gain ----
+        if (agc_enable && !agc_enable_prev) begin
+            agc_gain        <= encoding_to_signed(gain_shift);
+            holdoff_counter <= agc_holdoff;
+        end
+
+        // ---- Update current_gain output ----
+        if (agc_enable)
+            current_gain <= signed_to_encoding(agc_gain);
+        else
+            current_gain <= gain_shift;
     end
 end
 

9_Firmware/9_2_FPGA/scripts/50t/build_50t.tcl

@@ -120,9 +120,10 @@ set_property CLOCK_DEDICATED_ROUTE FALSE [get_nets {ft_clkout_IBUF}]
 
 # ---- Run implementation steps ----
 opt_design -directive Explore
-place_design -directive Explore
+place_design -directive ExtraNetDelay_high
+phys_opt_design -directive AggressiveExplore
+route_design -directive AggressiveExplore
 phys_opt_design -directive AggressiveExplore
-route_design -directive Explore
 phys_opt_design -directive AggressiveExplore
 
 set impl_elapsed [expr {[clock seconds] - $impl_start}]

9_Firmware/9_2_FPGA/tb/tb_rx_gain_control.v

@@ -38,10 +38,20 @@ reg signed [15:0] data_q_in;
 reg               valid_in;
 reg [3:0]         gain_shift;
 
+// AGC configuration (default: AGC disabled — manual mode)
+reg               agc_enable;
+reg [7:0]         agc_target;
+reg [3:0]         agc_attack;
+reg [3:0]         agc_decay;
+reg [3:0]         agc_holdoff;
+reg               frame_boundary;
+
 wire signed [15:0] data_i_out;
 wire signed [15:0] data_q_out;
 wire               valid_out;
 wire [7:0]         saturation_count;
+wire [7:0]         peak_magnitude;
+wire [3:0]         current_gain;
 
 rx_gain_control dut (
     .clk(clk),
@@ -50,10 +60,18 @@ rx_gain_control dut (
     .data_q_in(data_q_in),
     .valid_in(valid_in),
     .gain_shift(gain_shift),
+    .agc_enable(agc_enable),
+    .agc_target(agc_target),
+    .agc_attack(agc_attack),
+    .agc_decay(agc_decay),
+    .agc_holdoff(agc_holdoff),
+    .frame_boundary(frame_boundary),
     .data_i_out(data_i_out),
     .data_q_out(data_q_out),
     .valid_out(valid_out),
-    .saturation_count(saturation_count)
+    .saturation_count(saturation_count),
+    .peak_magnitude(peak_magnitude),
+    .current_gain(current_gain)
 );
 
 // ---------------------------------------------------------------
@@ -105,6 +123,13 @@ initial begin
     data_q_in  = 0;
     valid_in   = 0;
     gain_shift = 4'd0;
+    // AGC disabled for backward-compatible tests (Tests 1-12)
+    agc_enable     = 0;
+    agc_target     = 8'd200;
+    agc_attack     = 4'd1;
+    agc_decay      = 4'd1;
+    agc_holdoff    = 4'd4;
+    frame_boundary = 0;
 
     repeat (4) @(posedge clk);
     reset_n = 1;
@@ -152,6 +177,9 @@ initial begin
           "T3.1: I saturated to +32767");
     check(data_q_out == -16'sd32768,
           "T3.2: Q saturated to -32768");
+    // Pulse frame_boundary to snapshot the per-frame saturation count
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
     check(saturation_count == 8'd1,
           "T3.3: Saturation counter = 1 (both channels clipped counts as 1)");
 
@@ -173,6 +201,9 @@ initial begin
           "T4.1: I attenuated 4000>>2 = 1000");
     check(data_q_out == -16'sd500,
           "T4.2: Q attenuated -2000>>2 = -500");
+    // Pulse frame_boundary to snapshot (should be 0 — no clipping)
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
     check(saturation_count == 8'd0,
           "T4.3: No saturation on right shift");
 
@@ -315,13 +346,18 @@ initial begin
     valid_in = 1'b0;
     @(posedge clk); #1;
 
+    // Pulse frame_boundary to snapshot per-frame saturation count
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
     check(saturation_count == 8'd255,
           "T11.1: Counter capped at 255 after 256 saturating samples");
 
-    // One more sample — should stay at 255
+    // One more sample + frame boundary — should still be capped at 1 (new frame)
     send_sample(16'sd20000, 16'sd20000);
-    check(saturation_count == 8'd255,
-          "T11.2: Counter stays at 255 (no wrap)");
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    check(saturation_count == 8'd1,
+          "T11.2: New frame counter = 1 (single sample)");
 
     // ---------------------------------------------------------------
     // TEST 12: Reset clears everything
@@ -329,6 +365,8 @@ initial begin
     $display("");
     $display("--- Test 12: Reset clears all ---");
 
+    gain_shift = 4'd0;  // Reset gain_shift to 0 so current_gain reads 0
+    agc_enable = 0;
     reset_n = 0;
     repeat (2) @(posedge clk);
     reset_n = 1;
@@ -342,6 +380,479 @@ initial begin
           "T12.3: valid_out cleared on reset");
     check(saturation_count == 8'd0,
           "T12.4: Saturation counter cleared on reset");
+    check(current_gain == 4'd0,
+          "T12.5: current_gain cleared on reset");
+
+    // ---------------------------------------------------------------
+    // TEST 13: current_gain reflects gain_shift in manual mode
+    // ---------------------------------------------------------------
+    $display("");
+    $display("--- Test 13: current_gain tracks gain_shift (manual) ---");
+
+    gain_shift = 4'b0_011;  // amplify x8
+    @(posedge clk); @(posedge clk); #1;
+    check(current_gain == 4'b0011,
+          "T13.1: current_gain = 0x3 (amplify x8)");
+
+    gain_shift = 4'b1_010;  // attenuate /4
+    @(posedge clk); @(posedge clk); #1;
+    check(current_gain == 4'b1010,
+          "T13.2: current_gain = 0xA (attenuate /4)");
+
+    // ---------------------------------------------------------------
+    // TEST 14: Peak magnitude tracking
+    // ---------------------------------------------------------------
+    $display("");
+    $display("--- Test 14: Peak magnitude tracking ---");
+
+    reset_n = 0;
+    repeat (2) @(posedge clk);
+    reset_n = 1;
+    repeat (2) @(posedge clk);
+
+    gain_shift = 4'b0_000;  // pass-through
+    // Send samples with increasing magnitude
+    send_sample(16'sd100, 16'sd50);
+    send_sample(16'sd1000, 16'sd500);
+    send_sample(16'sd8000, 16'sd2000);   // peak = 8000
+    send_sample(16'sd200, 16'sd100);
+    // Pulse frame_boundary to snapshot
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    // peak_magnitude = upper 8 bits of 15-bit peak (8000)
+    // 8000 = 0x1F40, 15-bit = 0x1F40, [14:7] = 0x3E = 62
+    check(peak_magnitude == 8'd62,
+          "T14.1: Peak magnitude = 62 (8000 >> 7)");
+
+    // ---------------------------------------------------------------
+    // TEST 15: AGC auto gain-down on saturation
+    // ---------------------------------------------------------------
+    $display("");
+    $display("--- Test 15: AGC gain-down on saturation ---");
+
+    reset_n = 0;
+    repeat (2) @(posedge clk);
+    reset_n = 1;
+    repeat (2) @(posedge clk);
+
+    // Start with amplify x4 (gain_shift = 0x02), then enable AGC
+    gain_shift  = 4'b0_010;  // amplify x4, internal gain = +2
+    agc_enable  = 0;
+    agc_attack  = 4'd1;
+    agc_decay   = 4'd1;
+    agc_holdoff = 4'd2;
+    agc_target  = 8'd100;
+    @(posedge clk); @(posedge clk);
+
+    // Enable AGC — should initialize from gain_shift
+    agc_enable = 1;
+    @(posedge clk); @(posedge clk); @(posedge clk); #1;
+    check(current_gain == 4'b0010,
+          "T15.1: AGC initialized from gain_shift (amplify x4)");
+
+    // Send saturating samples (will clip at x4 gain)
+    send_sample(16'sd20000, 16'sd20000);
+    send_sample(16'sd20000, 16'sd20000);
+
+    // Pulse frame_boundary — AGC should reduce gain by attack=1
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    // current_gain lags agc_gain by 1 cycle (NBA), wait one extra cycle
+    @(posedge clk); #1;
+    // Internal gain was +2, attack=1 → new gain = +1 (0x01)
+    check(current_gain == 4'b0001,
+          "T15.2: AGC reduced gain to x2 after saturation");
+
+    // Another frame with saturation (20000*2 = 40000 > 32767)
+    send_sample(16'sd20000, 16'sd20000);
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    @(posedge clk); #1;
+    // gain was +1, attack=1 → new gain = 0 (0x00)
+    check(current_gain == 4'b0000,
+          "T15.3: AGC reduced gain to x1 (pass-through)");
+
+    // At gain 0 (pass-through), 20000 does NOT overflow 16-bit range,
+    // so no saturation occurs. Signal peak = 20000 >> 7 = 156 > target(100),
+    // so AGC correctly holds gain at 0. This is expected behavior.
+    // To test crossing into attenuation: increase attack to 3.
+    agc_attack = 4'd3;
+    // Reset and start fresh with gain +2, attack=3
+    reset_n = 0;
+    repeat (2) @(posedge clk);
+    reset_n = 1;
+    repeat (2) @(posedge clk);
+
+    gain_shift = 4'b0_010;  // amplify x4, internal gain = +2
+    agc_enable = 0;
+    @(posedge clk);
+    agc_enable = 1;
+    @(posedge clk); @(posedge clk); @(posedge clk); #1;
+
+    // Send saturating samples
+    send_sample(16'sd20000, 16'sd20000);
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    @(posedge clk); #1;
+    // gain was +2, attack=3 → new gain = -1 → encoding 0x09
+    check(current_gain == 4'b1001,
+          "T15.4: Large attack step crosses to attenuation (gain +2 - 3 = -1 → 0x9)");
+
+    // ---------------------------------------------------------------
+    // TEST 16: AGC auto gain-up after holdoff
+    // ---------------------------------------------------------------
+    $display("");
+    $display("--- Test 16: AGC gain-up after holdoff ---");
+
+    reset_n = 0;
+    repeat (2) @(posedge clk);
+    reset_n = 1;
+    repeat (2) @(posedge clk);
+
+    // Start with low gain, weak signal, holdoff=2
+    gain_shift  = 4'b0_000;  // pass-through (internal gain = 0)
+    agc_enable  = 0;
+    agc_attack  = 4'd1;
+    agc_decay   = 4'd1;
+    agc_holdoff = 4'd2;
+    agc_target  = 8'd100;  // target peak = 100 (in upper 8 bits = 12800 raw)
+    @(posedge clk); @(posedge clk);
+
+    agc_enable = 1;
+    @(posedge clk); @(posedge clk); #1;
+
+    // Frame 1: send weak signal (peak < target), holdoff counter = 2
+    send_sample(16'sd100, 16'sd50);  // peak=100, [14:7]=0 (very weak)
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    @(posedge clk); #1;
+    check(current_gain == 4'b0000,
+          "T16.1: Gain held during holdoff (frame 1, holdoff=2)");
+
+    // Frame 2: still weak, holdoff counter decrements to 1
+    send_sample(16'sd100, 16'sd50);
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    @(posedge clk); #1;
+    check(current_gain == 4'b0000,
+          "T16.2: Gain held during holdoff (frame 2, holdoff=1)");
+
+    // Frame 3: holdoff expired (was 0 at start of frame) → gain up
+    send_sample(16'sd100, 16'sd50);
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    @(posedge clk); #1;
+    check(current_gain == 4'b0001,
+          "T16.3: Gain increased after holdoff expired (gain 0->1)");
+
+    // ---------------------------------------------------------------
+    // TEST 17: Repeated attacks drive gain negative, clamp at -7,
+    //          then decay recovers
+    // ---------------------------------------------------------------
+    $display("");
+    $display("--- Test 17: Repeated attack → negative clamp → decay recovery ---");
+
+    // ----- 17a: Walk gain from +7 down through zero via repeated attack -----
+    reset_n = 0;
+    repeat (2) @(posedge clk);
+    reset_n = 1;
+    repeat (2) @(posedge clk);
+
+    gain_shift  = 4'b0_111;  // amplify x128, internal gain = +7
+    agc_enable  = 0;
+    agc_attack  = 4'd2;
+    agc_decay   = 4'd1;
+    agc_holdoff = 4'd2;
+    agc_target  = 8'd100;
+    @(posedge clk);
+    agc_enable = 1;
+    @(posedge clk); @(posedge clk); @(posedge clk); #1;
+    check(current_gain == 4'b0_111,
+          "T17a.1: AGC initialized at gain +7 (0x7)");
+
+    // Frame 1: saturating at gain +7 → gain 7-2=5
+    send_sample(16'sd1000, 16'sd1000);  // 1000<<7 = 128000 → overflow
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    @(posedge clk); #1;
+    check(current_gain == 4'b0_101,
+          "T17a.2: After attack: gain +5 (0x5)");
+
+    // Frame 2: still saturating at gain +5 → gain 5-2=3
+    send_sample(16'sd1000, 16'sd1000);  // 1000<<5 = 32000 → no overflow
+    send_sample(16'sd2000, 16'sd2000);  // 2000<<5 = 64000 → overflow
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    @(posedge clk); #1;
+    check(current_gain == 4'b0_011,
+          "T17a.3: After attack: gain +3 (0x3)");
+
+    // Frame 3: saturating at gain +3 → gain 3-2=1
+    send_sample(16'sd5000, 16'sd5000);  // 5000<<3 = 40000 → overflow
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    @(posedge clk); #1;
+    check(current_gain == 4'b0_001,
+          "T17a.4: After attack: gain +1 (0x1)");
+
+    // Frame 4: saturating at gain +1 → gain 1-2=-1 → encoding 0x9
+    send_sample(16'sd20000, 16'sd20000); // 20000<<1 = 40000 → overflow
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    @(posedge clk); #1;
+    check(current_gain == 4'b1_001,
+          "T17a.5: Attack crossed zero: gain -1 (0x9)");
+
+    // Frame 5: at gain -1 (right shift 1), 20000>>>1=10000, NO overflow.
+    // peak = 20000 → [14:7]=156 > target(100) → HOLD, gain stays -1
+    send_sample(16'sd20000, 16'sd20000);
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    @(posedge clk); #1;
+    check(current_gain == 4'b1_001,
+          "T17a.6: No overflow at -1, peak>target → HOLD, gain stays -1");
+
+    // ----- 17b: Max attack step clamps at -7 -----
+    $display("");
+    $display("--- Test 17b: Max attack clamps at -7 ---");
+
+    reset_n = 0;
+    repeat (2) @(posedge clk);
+    reset_n = 1;
+    repeat (2) @(posedge clk);
+
+    gain_shift  = 4'b0_011;  // amplify x8, internal gain = +3
+    agc_attack  = 4'd15;     // max attack step
+    agc_enable  = 0;
+    @(posedge clk);
+    agc_enable = 1;
+    @(posedge clk); @(posedge clk); @(posedge clk); #1;
+    check(current_gain == 4'b0_011,
+          "T17b.1: Initialized at gain +3");
+
+    // One saturating frame: gain = clamp(3 - 15) = clamp(-12) = -7 → 0xF
+    send_sample(16'sd5000, 16'sd5000);  // 5000<<3 = 40000 → overflow
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    @(posedge clk); #1;
+    check(current_gain == 4'b1_111,
+          "T17b.2: Gain clamped at -7 (0xF) after max attack");
+
+    // Another frame at gain -7: 5000>>>7 = 39, peak = 5000→[14:7]=39 < target(100)
+    // → decay path, but holdoff counter was reset to 2 by the attack above
+    send_sample(16'sd5000, 16'sd5000);
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    @(posedge clk); #1;
+    check(current_gain == 4'b1_111,
+          "T17b.3: Gain still -7 (holdoff active, 2→1)");
+
+    // ----- 17c: Decay recovery from -7 after holdoff -----
+    $display("");
+    $display("--- Test 17c: Decay recovery from deep negative ---");
+
+    // Holdoff was 2. After attack (frame above), holdoff=2.
+    // Frame after 17b.3: holdoff decrements to 0
+    send_sample(16'sd5000, 16'sd5000);
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    @(posedge clk); #1;
+    check(current_gain == 4'b1_111,
+          "T17c.1: Gain still -7 (holdoff 1→0)");
+
+    // Now holdoff=0, next weak frame should trigger decay: -7 + 1 = -6 → 0xE
+    send_sample(16'sd5000, 16'sd5000);
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    @(posedge clk); #1;
+    check(current_gain == 4'b1_110,
+          "T17c.2: Decay from -7 to -6 (0xE) after holdoff expired");
+
+    // One more decay: -6 + 1 = -5 → 0xD
+    send_sample(16'sd5000, 16'sd5000);
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    @(posedge clk); #1;
+    check(current_gain == 4'b1_101,
+          "T17c.3: Decay from -6 to -5 (0xD)");
+
+    // Verify output is actually attenuated: at gain -5 (right shift 5),
+    // 5000 >>> 5 = 156
+    send_sample(16'sd5000, 16'sd0);
+    check(data_i_out == 16'sd156,
+          "T17c.4: Output correctly attenuated: 5000>>>5 = 156");
+
+    // =================================================================
+    // Test 18: valid_in + frame_boundary on the SAME cycle
+    // Verify the coincident sample is included in the frame snapshot
+    // (Bug #7 fix — previously lost due to NBA last-write-wins)
+    // =================================================================
+    $display("");
+    $display("--- Test 18: valid_in + frame_boundary simultaneous ---");
+
+    // ----- 18a: Coincident saturating sample included in sat count -----
+    reset_n = 0;
+    repeat (2) @(posedge clk);
+    reset_n = 1;
+    repeat (2) @(posedge clk);
+
+    gain_shift  = 4'b0_011;  // amplify x8 (shift left 3)
+    agc_attack  = 4'd1;
+    agc_decay   = 4'd1;
+    agc_holdoff = 4'd2;
+    agc_target  = 8'd100;
+    agc_enable  = 1;
+    @(posedge clk); @(posedge clk); @(posedge clk); #1;
+
+    // Send one normal sample first (establishes a non-zero frame)
+    send_sample(16'sd100, 16'sd100);  // small, no overflow at gain +3
+
+    // Now: assert valid_in AND frame_boundary on the SAME posedge.
+    // The sample is large enough to overflow at gain +3: 5000<<3 = 40000 > 32767
+    @(negedge clk);
+    data_i_in      = 16'sd5000;
+    data_q_in      = 16'sd5000;
+    valid_in       = 1'b1;
+    frame_boundary = 1'b1;
+    @(posedge clk); #1;  // DUT samples both signals
+    @(negedge clk);
+    valid_in       = 1'b0;
+    frame_boundary = 1'b0;
+    @(posedge clk); #1;  // let NBA settle
+    @(posedge clk); #1;
+
+    // Saturation count should be 1 (the coincident sample overflowed)
+    check(saturation_count == 8'd1,
+          "T18a.1: Coincident saturating sample counted in snapshot (sat_count=1)");
+
+    // Peak should reflect pre-gain max(|5000|,|5000|) = 5000 → [14:7] = 39
+    // (or at least >= the first sample's peak of 100→[14:7]=0)
+    check(peak_magnitude == 8'd39,
+          "T18a.2: Coincident sample peak included in snapshot (peak=39)");
+
+    // AGC should have attacked (sat > 0): gain +3 → +3-1 = +2
+    check(current_gain == 4'b0_010,
+          "T18a.3: AGC attacked on coincident saturation (gain +3 → +2)");
+
+    // ----- 18b: Coincident non-saturating peak updates snapshot -----
+    $display("");
+    $display("--- Test 18b: Coincident peak-only sample ---");
+
+    reset_n = 0;
+    agc_enable  = 0;  // deassert so transition fires with NEW gain_shift
+    repeat (2) @(posedge clk);
+    reset_n = 1;
+    repeat (2) @(posedge clk);
+
+    gain_shift  = 4'b0_000;  // no amplification (shift 0)
+    agc_attack  = 4'd1;
+    agc_decay   = 4'd1;
+    agc_holdoff = 4'd0;
+    agc_target  = 8'd200;    // high target so signal is "weak"
+    agc_enable  = 1;
+    @(posedge clk); @(posedge clk); @(posedge clk); #1;
+
+    // Send a small sample
+    send_sample(16'sd50, 16'sd50);
+
+    // Coincident frame_boundary + valid_in with a LARGER sample (not saturating)
+    @(negedge clk);
+    data_i_in      = 16'sd10000;
+    data_q_in      = 16'sd10000;
+    valid_in       = 1'b1;
+    frame_boundary = 1'b1;
+    @(posedge clk); #1;
+    @(negedge clk);
+    valid_in       = 1'b0;
+    frame_boundary = 1'b0;
+    @(posedge clk); #1;
+    @(posedge clk); #1;
+
+    // Peak should be max(|10000|,|10000|) = 10000 → [14:7] = 78
+    check(peak_magnitude == 8'd78,
+          "T18b.1: Coincident larger peak included (peak=78)");
+    // No saturation at gain 0
+    check(saturation_count == 8'd0,
+          "T18b.2: No saturation (gain=0, no overflow)");
+
+    // =================================================================
+    // Test 19: AGC enable toggle mid-frame
+    // Verify gain initializes from gain_shift and holdoff resets
+    // =================================================================
+    $display("");
+    $display("--- Test 19: AGC enable toggle mid-frame ---");
+
+    // ----- 19a: Enable AGC mid-frame, verify gain init -----
+    reset_n = 0;
+    repeat (2) @(posedge clk);
+    reset_n = 1;
+    repeat (2) @(posedge clk);
+
+    gain_shift  = 4'b0_101;  // amplify x32 (shift left 5), internal = +5
+    agc_attack  = 4'd2;
+    agc_decay   = 4'd1;
+    agc_holdoff = 4'd3;
+    agc_target  = 8'd100;
+    agc_enable  = 0;         // start disabled
+    @(posedge clk); #1;
+
+    // With AGC off, current_gain should follow gain_shift directly
+    check(current_gain == 4'b0_101,
+          "T19a.1: AGC disabled → current_gain = gain_shift (0x5)");
+
+    // Send a few samples (building up frame metrics)
+    send_sample(16'sd1000, 16'sd1000);
+    send_sample(16'sd2000, 16'sd2000);
+
+    // Toggle AGC enable ON mid-frame
+    @(negedge clk);
+    agc_enable = 1;
+    @(posedge clk); #1;
+    @(posedge clk); #1;  // let enable transition register
+
+    // Gain should initialize from gain_shift encoding (0b0_101 → +5)
+    check(current_gain == 4'b0_101,
+          "T19a.2: AGC enabled mid-frame → gain initialized from gain_shift (+5)");
+
+    // Send a saturating sample, then boundary
+    send_sample(16'sd5000, 16'sd5000);  // 5000<<5 overflows
+    @(negedge clk); frame_boundary = 1; @(posedge clk); #1;
+    @(negedge clk); frame_boundary = 0; @(posedge clk); #1;
+    @(posedge clk); #1;
+
+    // AGC should attack: gain +5 → +5-2 = +3
+    check(current_gain == 4'b0_011,
+          "T19a.3: After boundary, AGC attacked (gain +5 → +3)");
+
+    // ----- 19b: Disable AGC mid-frame, verify passthrough -----
+    $display("");
+    $display("--- Test 19b: Disable AGC mid-frame ---");
+
+    // Change gain_shift to a new value
+    @(negedge clk);
+    gain_shift = 4'b1_010;  // attenuate by 2 (right shift 2)
+    agc_enable = 0;
+    @(posedge clk); #1;
+    @(posedge clk); #1;
+
+    // With AGC off, current_gain should follow gain_shift
+    check(current_gain == 4'b1_010,
+          "T19b.1: AGC disabled → current_gain = gain_shift (0xA, atten 2)");
+
+    // Send sample: 1000 >> 2 = 250
+    send_sample(16'sd1000, 16'sd0);
+    check(data_i_out == 16'sd250,
+          "T19b.2: Output uses host gain_shift when AGC off: 1000>>2=250");
+
+    // ----- 19c: Re-enable, verify gain re-initializes -----
+    @(negedge clk);
+    gain_shift = 4'b0_010;  // amplify by 4 (shift left 2), internal = +2
+    agc_enable = 1;
+    @(posedge clk); #1;
+    @(posedge clk); #1;
+
+    check(current_gain == 4'b0_010,
+          "T19c.1: AGC re-enabled → gain re-initialized from gain_shift (+2)");
 
     // ---------------------------------------------------------------
     // SUMMARY

9_Firmware/9_2_FPGA/tb/tb_usb_data_interface.v

@@ -79,6 +79,12 @@ module tb_usb_data_interface;
     reg  [7:0]  status_self_test_detail;
     reg         status_self_test_busy;
 
+    // AGC status readback inputs
+    reg  [3:0]  status_agc_current_gain;
+    reg  [7:0]  status_agc_peak_magnitude;
+    reg  [7:0]  status_agc_saturation_count;
+    reg         status_agc_enable;
+
     // ── Clock generators (asynchronous) ────────────────────────
     always #(CLK_PERIOD / 2) clk = ~clk;
     always #(FT_CLK_PERIOD / 2) ft601_clk_in = ~ft601_clk_in;
@@ -134,7 +140,13 @@ module tb_usb_data_interface;
         // Self-test status readback
         .status_self_test_flags (status_self_test_flags),
         .status_self_test_detail(status_self_test_detail),
-        .status_self_test_busy  (status_self_test_busy)
+        .status_self_test_busy  (status_self_test_busy),
+
+        // AGC status readback
+        .status_agc_current_gain    (status_agc_current_gain),
+        .status_agc_peak_magnitude  (status_agc_peak_magnitude),
+        .status_agc_saturation_count(status_agc_saturation_count),
+        .status_agc_enable          (status_agc_enable)
     );
 
     // ── Test bookkeeping ───────────────────────────────────────
@@ -194,6 +206,10 @@ module tb_usb_data_interface;
             status_self_test_flags  = 5'b00000;
             status_self_test_detail = 8'd0;
             status_self_test_busy   = 1'b0;
+            status_agc_current_gain     = 4'd0;
+            status_agc_peak_magnitude   = 8'd0;
+            status_agc_saturation_count = 8'd0;
+            status_agc_enable           = 1'b0;
             repeat (6) @(posedge ft601_clk_in);
             reset_n = 1;
             // Wait enough cycles for stream_control CDC to propagate
@@ -902,6 +918,11 @@ module tb_usb_data_interface;
         status_self_test_flags  = 5'b11111;
         status_self_test_detail = 8'hA5;
         status_self_test_busy   = 1'b0;
+        // AGC status: gain=5, peak=180, sat_count=12, enabled
+        status_agc_current_gain     = 4'd5;
+        status_agc_peak_magnitude   = 8'd180;
+        status_agc_saturation_count = 8'd12;
+        status_agc_enable           = 1'b1;
 
         // Pulse status_request (1 cycle in clk domain — toggles status_req_toggle_100m)
         @(posedge clk);
@@ -958,8 +979,8 @@ module tb_usb_data_interface;
               "Status readback: word 2 = {guard, short_chirp}");
         check(uut.status_words[3] === {16'd17450, 10'd0, 6'd32},
               "Status readback: word 3 = {short_listen, 0, chirps_per_elev}");
-        check(uut.status_words[4] === {30'd0, 2'b10},
-              "Status readback: word 4 = range_mode=2'b10");
+        check(uut.status_words[4] === {4'd5, 8'd180, 8'd12, 1'b1, 9'd0, 2'b10},
+              "Status readback: word 4 = {agc_gain=5, peak=180, sat=12, en=1, range_mode=2}");
         // status_words[5] = {7'd0, busy, 8'd0, detail[7:0], 3'd0, flags[4:0]}
         // = {7'd0, 1'b0, 8'd0, 8'hA5, 3'd0, 5'b11111}
         check(uut.status_words[5] === {7'd0, 1'b0, 8'd0, 8'hA5, 3'd0, 5'b11111},

9_Firmware/9_2_FPGA/usb_data_interface.v

@@ -20,8 +20,8 @@ module usb_data_interface (
     // Control signals
     output reg ft601_txe_n,          // Transmit enable (active low)
     output reg ft601_rxf_n,          // Receive enable (active low)
-    input wire ft601_txe,             // Transmit FIFO empty
-    input wire ft601_rxf,             // Receive FIFO full
+    input wire ft601_txe,             // TXE: Transmit FIFO Not Full (high = space available to write)
+    input wire ft601_rxf,             // RXF: Receive FIFO Not Empty (high = data available to read)
     output reg ft601_wr_n,            // Write strobe (active low)
     output reg ft601_rd_n,            // Read strobe (active low)
     output reg ft601_oe_n,            // Output enable (active low)
@@ -77,7 +77,13 @@ module usb_data_interface (
     // Self-test status readback (opcode 0x31 / included in 0xFF status packet)
     input wire [4:0]  status_self_test_flags,  // Per-test PASS(1)/FAIL(0) latched
     input wire [7:0]  status_self_test_detail, // Diagnostic detail byte latched
-    input wire        status_self_test_busy    // Self-test FSM still running
+    input wire        status_self_test_busy,   // Self-test FSM still running
+
+    // AGC status readback
+    input wire [3:0]  status_agc_current_gain,
+    input wire [7:0]  status_agc_peak_magnitude,
+    input wire [7:0]  status_agc_saturation_count,
+    input wire        status_agc_enable
 );
 
 // USB packet structure (same as before)
@@ -267,8 +273,13 @@ always @(posedge ft601_clk_in or negedge ft601_reset_n) begin
             status_words[2] <= {status_guard, status_short_chirp};
             // Word 3: {short_listen_cycles[15:0], chirps_per_elev[5:0], 10'b0}
             status_words[3] <= {status_short_listen, 10'd0, status_chirps_per_elev};
-            // Word 4: Fix 7 — range_mode in bits [1:0], rest reserved
-            status_words[4] <= {30'd0, status_range_mode};
+            // Word 4: AGC metrics + range_mode
+            status_words[4] <= {status_agc_current_gain,        // [31:28]
+                                status_agc_peak_magnitude,      // [27:20]
+                                status_agc_saturation_count,    // [19:12]
+                                status_agc_enable,              // [11]
+                                9'd0,                           // [10:2] reserved
+                                status_range_mode};             // [1:0]
             // Word 5: Self-test results {reserved[6:0], busy, reserved[7:0], detail[7:0], reserved[2:0], flags[4:0]}
             status_words[5] <= {7'd0, status_self_test_busy,
                                 8'd0, status_self_test_detail,

9_Firmware/9_2_FPGA/usb_data_interface_ft2232h.v

@@ -90,7 +90,13 @@ module usb_data_interface_ft2232h (
     // Self-test status readback
     input wire [4:0]  status_self_test_flags,
     input wire [7:0]  status_self_test_detail,
-    input wire        status_self_test_busy
+    input wire        status_self_test_busy,
+
+    // AGC status readback
+    input wire [3:0]  status_agc_current_gain,
+    input wire [7:0]  status_agc_peak_magnitude,
+    input wire [7:0]  status_agc_saturation_count,
+    input wire        status_agc_enable
 );
 
 // ============================================================================
@@ -281,7 +287,12 @@ always @(posedge ft_clk or negedge ft_reset_n) begin
             status_words[1] <= {status_long_chirp, status_long_listen};
             status_words[2] <= {status_guard, status_short_chirp};
             status_words[3] <= {status_short_listen, 10'd0, status_chirps_per_elev};
-            status_words[4] <= {30'd0, status_range_mode};
+            status_words[4] <= {status_agc_current_gain,        // [31:28]
+                                status_agc_peak_magnitude,      // [27:20]
+                                status_agc_saturation_count,    // [19:12]
+                                status_agc_enable,              // [11]
+                                9'd0,                           // [10:2] reserved
+                                status_range_mode};             // [1:0]
             status_words[5] <= {7'd0, status_self_test_busy,
                                 8'd0, status_self_test_detail,
                                 3'd0, status_self_test_flags};

9_Firmware/9_3_GUI/adi_agc_analysis.py

@@ -0,0 +1,431 @@
+# ruff: noqa: T201
+#!/usr/bin/env python3
+"""
+One-off AGC saturation analysis for ADI CN0566 raw IQ captures.
+
+Bit-accurate simulation of rx_gain_control.v AGC inner loop applied
+to real captured IQ data.  Three scenarios per dataset:
+
+  Row 1 — AGC OFF:  Fixed gain_shift=0 (pass-through).  Shows raw clipping.
+  Row 2 — AGC ON:   Auto-adjusts from gain_shift=0.  Clipping clears.
+  Row 3 — AGC delayed: OFF for first half, ON at midpoint.
+           Shows the transition: clipping → AGC activates → clears.
+
+Key RTL details modelled exactly:
+  - gain_shift[3]=direction (0=amplify/left, 1=attenuate/right), [2:0]=amount
+  - Internal agc_gain is signed -7..+7
+  - Peak is measured PRE-gain (raw input |sample|, upper 8 of 15 bits)
+  - Saturation is measured POST-gain (overflow from shift)
+  - Attack: gain -= agc_attack when any sample clips (immediate)
+  - Decay: gain += agc_decay when peak < target AND holdoff expired
+  - Hold: when peak >= target AND no saturation, hold gain, reset holdoff
+
+Usage:
+  python adi_agc_analysis.py
+  python adi_agc_analysis.py --data /path/to/file.npy --label "my capture"
+"""
+
+import argparse
+import sys
+from pathlib import Path
+
+import matplotlib.pyplot as plt
+import numpy as np
+
+# ---------------------------------------------------------------------------
+# FPGA AGC parameters (rx_gain_control.v reset defaults)
+# ---------------------------------------------------------------------------
+AGC_TARGET = 200       # host_agc_target (8-bit, default 200)
+AGC_ATTACK = 1         # host_agc_attack (4-bit, default 1)
+AGC_DECAY = 1          # host_agc_decay  (4-bit, default 1)
+AGC_HOLDOFF = 4        # host_agc_holdoff (4-bit, default 4)
+ADC_RAIL = 4095        # 12-bit ADC max absolute value
+
+
+# ---------------------------------------------------------------------------
+# Gain encoding helpers (match RTL signed_to_encoding / encoding_to_signed)
+# ---------------------------------------------------------------------------
+
+def signed_to_encoding(g: int) -> int:
+    """Convert signed gain (-7..+7) to gain_shift[3:0] encoding.
+    [3]=0, [2:0]=N → amplify (left shift) by N
+    [3]=1, [2:0]=N → attenuate (right shift) by N
+    """
+    if g >= 0:
+        return g & 0x07
+    return 0x08 | ((-g) & 0x07)
+
+
+def encoding_to_signed(enc: int) -> int:
+    """Convert gain_shift[3:0] encoding to signed gain."""
+    if (enc & 0x08) == 0:
+        return enc & 0x07
+    return -(enc & 0x07)
+
+
+def clamp_gain(val: int) -> int:
+    """Clamp to [-7, +7] (matches RTL clamp_gain function)."""
+    return max(-7, min(7, val))
+
+
+# ---------------------------------------------------------------------------
+# Apply gain shift to IQ data (matches RTL combinational logic)
+# ---------------------------------------------------------------------------
+
+def apply_gain_shift(frame_i: np.ndarray, frame_q: np.ndarray,
+                     gain_enc: int) -> tuple[np.ndarray, np.ndarray, int]:
+    """Apply gain_shift encoding to 16-bit signed IQ arrays.
+
+    Returns (shifted_i, shifted_q, overflow_count).
+    Matches the RTL: left shift = amplify, right shift = attenuate,
+    saturate to ±32767 on overflow.
+    """
+    direction = (gain_enc >> 3) & 1  # 0=amplify, 1=attenuate
+    amount = gain_enc & 0x07
+
+    if amount == 0:
+        return frame_i.copy(), frame_q.copy(), 0
+
+    if direction == 0:
+        # Left shift (amplify)
+        si = frame_i.astype(np.int64) * (1 << amount)
+        sq = frame_q.astype(np.int64) * (1 << amount)
+    else:
+        # Arithmetic right shift (attenuate)
+        si = frame_i.astype(np.int64) >> amount
+        sq = frame_q.astype(np.int64) >> amount
+
+    # Count overflows (post-shift values outside 16-bit signed range)
+    overflow_i = (si > 32767) | (si < -32768)
+    overflow_q = (sq > 32767) | (sq < -32768)
+    overflow_count = int((overflow_i | overflow_q).sum())
+
+    # Saturate to ±32767
+    si = np.clip(si, -32768, 32767).astype(np.int16)
+    sq = np.clip(sq, -32768, 32767).astype(np.int16)
+
+    return si, sq, overflow_count
+
+
+# ---------------------------------------------------------------------------
+# Per-frame AGC simulation (bit-accurate to rx_gain_control.v)
+# ---------------------------------------------------------------------------
+
+def simulate_agc(frames: np.ndarray, agc_enabled: bool = True,
+                 enable_at_frame: int = 0,
+                 initial_gain_enc: int = 0x00) -> dict:
+    """Simulate FPGA inner-loop AGC across all frames.
+
+    Parameters
+    ----------
+    frames : (N, chirps, samples) complex — raw ADC captures (12-bit range)
+    agc_enabled : if False, gain stays fixed
+    enable_at_frame : frame index where AGC activates
+    initial_gain_enc : gain_shift[3:0] encoding when AGC enables (default 0x00 = pass-through)
+    """
+    n_frames = frames.shape[0]
+
+    # Output arrays
+    out_gain_enc = np.zeros(n_frames, dtype=int)     # gain_shift encoding [3:0]
+    out_gain_signed = np.zeros(n_frames, dtype=int)   # signed gain for plotting
+    out_peak_mag = np.zeros(n_frames, dtype=int)      # peak_magnitude[7:0]
+    out_sat_count = np.zeros(n_frames, dtype=int)     # saturation_count[7:0]
+    out_sat_rate = np.zeros(n_frames, dtype=float)
+    out_rms_post = np.zeros(n_frames, dtype=float)    # RMS after gain shift
+
+    # AGC internal state
+    agc_gain = 0          # signed, -7..+7
+    holdoff_counter = 0
+    agc_was_enabled = False
+
+    for i in range(n_frames):
+        frame = frames[i]
+        # Quantize to 16-bit signed (ADC is 12-bit, sign-extended to 16)
+        frame_i = np.clip(np.round(frame.real), -32768, 32767).astype(np.int16)
+        frame_q = np.clip(np.round(frame.imag), -32768, 32767).astype(np.int16)
+
+        # --- PRE-gain peak measurement (RTL lines 133-135, 211-213) ---
+        abs_i = np.abs(frame_i.astype(np.int32))
+        abs_q = np.abs(frame_q.astype(np.int32))
+        max_iq = np.maximum(abs_i, abs_q)
+        frame_peak_15bit = int(max_iq.max())  # 15-bit unsigned
+        peak_8bit = (frame_peak_15bit >> 7) & 0xFF  # Upper 8 bits
+
+        # --- Determine effective gain ---
+        agc_active = agc_enabled and (i >= enable_at_frame)
+
+        # AGC enable transition (RTL lines 250-253)
+        if agc_active and not agc_was_enabled:
+            agc_gain = encoding_to_signed(initial_gain_enc)
+            holdoff_counter = AGC_HOLDOFF
+
+        effective_enc = signed_to_encoding(agc_gain) if agc_active else initial_gain_enc
+
+        agc_was_enabled = agc_active
+
+        # --- Apply gain shift + count POST-gain overflow (RTL lines 114-126, 207-209) ---
+        shifted_i, shifted_q, frame_overflow = apply_gain_shift(
+            frame_i, frame_q, effective_enc)
+        frame_sat = min(255, frame_overflow)
+
+        # RMS of shifted signal
+        rms = float(np.sqrt(np.mean(
+            shifted_i.astype(np.float64)**2 + shifted_q.astype(np.float64)**2)))
+
+        total_samples = frame_i.size + frame_q.size
+        sat_rate = frame_overflow / total_samples if total_samples > 0 else 0.0
+
+        # --- Record outputs ---
+        out_gain_enc[i] = effective_enc
+        out_gain_signed[i] = agc_gain if agc_active else encoding_to_signed(initial_gain_enc)
+        out_peak_mag[i] = peak_8bit
+        out_sat_count[i] = frame_sat
+        out_sat_rate[i] = sat_rate
+        out_rms_post[i] = rms
+
+        # --- AGC update at frame boundary (RTL lines 226-246) ---
+        if agc_active:
+            if frame_sat > 0:
+                # Clipping: reduce gain immediately (attack)
+                agc_gain = clamp_gain(agc_gain - AGC_ATTACK)
+                holdoff_counter = AGC_HOLDOFF
+            elif peak_8bit < AGC_TARGET:
+                # Signal too weak: increase gain after holdoff
+                if holdoff_counter == 0:
+                    agc_gain = clamp_gain(agc_gain + AGC_DECAY)
+                else:
+                    holdoff_counter -= 1
+            else:
+                # Good range (peak >= target, no sat): hold, reset holdoff
+                holdoff_counter = AGC_HOLDOFF
+
+    return {
+        "gain_enc": out_gain_enc,
+        "gain_signed": out_gain_signed,
+        "peak_mag": out_peak_mag,
+        "sat_count": out_sat_count,
+        "sat_rate": out_sat_rate,
+        "rms_post": out_rms_post,
+    }
+
+
+# ---------------------------------------------------------------------------
+# Range-Doppler processing for heatmap display
+# ---------------------------------------------------------------------------
+
+def process_frame_rd(frame: np.ndarray, gain_enc: int,
+                     n_range: int = 64,
+                     n_doppler: int = 32) -> np.ndarray:
+    """Range-Doppler magnitude for one frame with gain applied."""
+    frame_i = np.clip(np.round(frame.real), -32768, 32767).astype(np.int16)
+    frame_q = np.clip(np.round(frame.imag), -32768, 32767).astype(np.int16)
+    si, sq, _ = apply_gain_shift(frame_i, frame_q, gain_enc)
+
+    iq = si.astype(np.float64) + 1j * sq.astype(np.float64)
+    n_chirps, _ = iq.shape
+
+    range_fft = np.fft.fft(iq, axis=1)[:, :n_range]
+    doppler_fft = np.fft.fftshift(np.fft.fft(range_fft, axis=0), axes=0)
+    center = n_chirps // 2
+    half_d = n_doppler // 2
+    doppler_fft = doppler_fft[center - half_d:center + half_d, :]
+
+    rd_mag = np.abs(doppler_fft.real) + np.abs(doppler_fft.imag)
+    return rd_mag.T  # (n_range, n_doppler)
+
+
+# ---------------------------------------------------------------------------
+# Plotting
+# ---------------------------------------------------------------------------
+
+def plot_scenario(axes, data: np.ndarray, agc: dict, title: str,
+                  enable_frame: int = 0):
+    """Plot one AGC scenario across 5 axes."""
+    n = data.shape[0]
+    xs = np.arange(n)
+
+    # Range-Doppler heatmap
+    if enable_frame > 0 and enable_frame < n:
+        f_before = max(0, enable_frame - 1)
+        f_after = min(n - 1, n - 2)
+        rd_before = process_frame_rd(data[f_before], int(agc["gain_enc"][f_before]))
+        rd_after = process_frame_rd(data[f_after], int(agc["gain_enc"][f_after]))
+        combined = np.hstack([rd_before, rd_after])
+        im = axes[0].imshow(
+            20 * np.log10(combined + 1), aspect="auto", origin="lower",
+            cmap="inferno", interpolation="nearest")
+        axes[0].axvline(x=rd_before.shape[1] - 0.5, color="cyan",
+                        linewidth=2, linestyle="--")
+        axes[0].set_title(f"{title}\nL: f{f_before} (pre) | R: f{f_after} (post)")
+    else:
+        worst = int(np.argmax(agc["sat_count"]))
+        best = int(np.argmin(agc["sat_count"]))
+        f_show = worst if agc["sat_count"][worst] > 0 else best
+        rd = process_frame_rd(data[f_show], int(agc["gain_enc"][f_show]))
+        im = axes[0].imshow(
+            20 * np.log10(rd + 1), aspect="auto", origin="lower",
+            cmap="inferno", interpolation="nearest")
+        axes[0].set_title(f"{title}\nFrame {f_show}")
+
+    axes[0].set_xlabel("Doppler bin")
+    axes[0].set_ylabel("Range bin")
+    plt.colorbar(im, ax=axes[0], label="dB", shrink=0.8)
+
+    # Signed gain history (the real AGC state)
+    axes[1].plot(xs, agc["gain_signed"], color="#00ff88", linewidth=1.5)
+    axes[1].axhline(y=0, color="gray", linestyle=":", alpha=0.5,
+                    label="Pass-through")
+    if enable_frame > 0:
+        axes[1].axvline(x=enable_frame, color="yellow", linewidth=2,
+                        linestyle="--", label="AGC ON")
+    axes[1].set_ylim(-8, 8)
+    axes[1].set_ylabel("Gain (signed)")
+    axes[1].set_title("AGC Internal Gain (-7=max atten, +7=max amp)")
+    axes[1].legend(fontsize=7, loc="upper right")
+    axes[1].grid(True, alpha=0.3)
+
+    # Peak magnitude (PRE-gain, 8-bit)
+    axes[2].plot(xs, agc["peak_mag"], color="#ffaa00", linewidth=1.0)
+    axes[2].axhline(y=AGC_TARGET, color="cyan", linestyle="--",
+                    alpha=0.7, label=f"Target ({AGC_TARGET})")
+    axes[2].axhspan(240, 255, color="red", alpha=0.15, label="Clip zone")
+    if enable_frame > 0:
+        axes[2].axvline(x=enable_frame, color="yellow", linewidth=2,
+                        linestyle="--", alpha=0.8)
+    axes[2].set_ylim(0, 260)
+    axes[2].set_ylabel("Peak (8-bit)")
+    axes[2].set_title("Peak Magnitude (pre-gain, raw input)")
+    axes[2].legend(fontsize=7, loc="upper right")
+    axes[2].grid(True, alpha=0.3)
+
+    # Saturation count (POST-gain overflow)
+    axes[3].fill_between(xs, agc["sat_count"], color="red", alpha=0.4)
+    axes[3].plot(xs, agc["sat_count"], color="red", linewidth=0.8)
+    if enable_frame > 0:
+        axes[3].axvline(x=enable_frame, color="yellow", linewidth=2,
+                        linestyle="--", alpha=0.8)
+    axes[3].set_ylabel("Overflow Count")
+    total = int(agc["sat_count"].sum())
+    axes[3].set_title(f"Post-Gain Overflow (total={total})")
+    axes[3].grid(True, alpha=0.3)
+
+    # RMS signal level (post-gain)
+    axes[4].plot(xs, agc["rms_post"], color="#44aaff", linewidth=1.0)
+    if enable_frame > 0:
+        axes[4].axvline(x=enable_frame, color="yellow", linewidth=2,
+                        linestyle="--", alpha=0.8)
+    axes[4].set_ylabel("RMS")
+    axes[4].set_xlabel("Frame")
+    axes[4].set_title("Post-Gain RMS Level")
+    axes[4].grid(True, alpha=0.3)
+
+
+def analyze_dataset(data: np.ndarray, label: str):
+    """Run 3-scenario analysis for one dataset."""
+    n_frames = data.shape[0]
+    mid = n_frames // 2
+
+    print(f"\n{'='*60}")
+    print(f"  {label}  —  shape {data.shape}")
+    print(f"{'='*60}")
+
+    # Raw ADC stats
+    raw_sat = np.sum((np.abs(data.real) >= ADC_RAIL) |
+                     (np.abs(data.imag) >= ADC_RAIL))
+    print(f"  Raw ADC saturation: {raw_sat} samples "
+          f"({100*raw_sat/(2*data.size):.2f}%)")
+
+    # Scenario 1: AGC OFF — pass-through (gain_shift=0x00)
+    print("  [1/3] AGC OFF (gain=0, pass-through) ...")
+    agc_off = simulate_agc(data, agc_enabled=False, initial_gain_enc=0x00)
+    print(f"        Post-gain overflow: {agc_off['sat_count'].sum()} "
+          f"(should be 0 — no amplification)")
+
+    # Scenario 2: AGC ON from frame 0
+    print("  [2/3] AGC ON (from start) ...")
+    agc_on = simulate_agc(data, agc_enabled=True, enable_at_frame=0,
+                          initial_gain_enc=0x00)
+    print(f"        Final gain: {agc_on['gain_signed'][-1]} "
+          f"(enc=0x{agc_on['gain_enc'][-1]:X})")
+    print(f"        Post-gain overflow: {agc_on['sat_count'].sum()}")
+
+    # Scenario 3: AGC delayed
+    print(f"  [3/3] AGC delayed (ON at frame {mid}) ...")
+    agc_delayed = simulate_agc(data, agc_enabled=True,
+                               enable_at_frame=mid,
+                               initial_gain_enc=0x00)
+    pre_sat = int(agc_delayed["sat_count"][:mid].sum())
+    post_sat = int(agc_delayed["sat_count"][mid:].sum())
+    print(f"        Pre-AGC overflow: {pre_sat}  "
+          f"Post-AGC overflow: {post_sat}")
+
+    # Plot
+    fig, axes = plt.subplots(3, 5, figsize=(28, 14))
+    fig.suptitle(f"AERIS-10 AGC Analysis — {label}\n"
+                 f"({n_frames} frames, {data.shape[1]} chirps, "
+                 f"{data.shape[2]} samples/chirp, "
+                 f"raw ADC sat={100*raw_sat/(2*data.size):.2f}%)",
+                 fontsize=13, fontweight="bold", y=0.99)
+
+    plot_scenario(axes[0], data, agc_off, "AGC OFF (pass-through)")
+    plot_scenario(axes[1], data, agc_on, "AGC ON (from start)")
+    plot_scenario(axes[2], data, agc_delayed,
+                  f"AGC delayed (ON at frame {mid})", enable_frame=mid)
+
+    for ax, lbl in zip(axes[:, 0],
+                       ["AGC OFF", "AGC ON", "AGC DELAYED"],
+                       strict=True):
+        ax.annotate(lbl, xy=(-0.35, 0.5), xycoords="axes fraction",
+                    fontsize=13, fontweight="bold", color="white",
+                    ha="center", va="center", rotation=90)
+
+    plt.tight_layout(rect=[0.03, 0, 1, 0.95])
+    return fig
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="AGC analysis for ADI raw IQ captures "
+                    "(bit-accurate rx_gain_control.v simulation)")
+    parser.add_argument("--amp", type=str,
+                        default=str(Path.home() / "Downloads/adi_radar_data"
+                                    "/amp_radar"
+                                    "/phaser_amp_4MSPS_500M_300u_256_m3dB.npy"),
+                        help="Path to amplified radar .npy")
+    parser.add_argument("--noamp", type=str,
+                        default=str(Path.home() / "Downloads/adi_radar_data"
+                                    "/no_amp_radar"
+                                    "/phaser_NOamp_4MSPS_500M_300u_256.npy"),
+                        help="Path to non-amplified radar .npy")
+    parser.add_argument("--data", type=str, default=None,
+                        help="Single dataset mode")
+    parser.add_argument("--label", type=str, default="Custom Data")
+    args = parser.parse_args()
+
+    plt.style.use("dark_background")
+
+    if args.data:
+        data = np.load(args.data)
+        analyze_dataset(data, args.label)
+        plt.show()
+        return
+
+    figs = []
+    for path, label in [(args.amp, "With Amplifier (-3 dB)"),
+                        (args.noamp, "No Amplifier")]:
+        if not Path(path).exists():
+            print(f"WARNING: {path} not found, skipping")
+            continue
+        data = np.load(path)
+        fig = analyze_dataset(data, label)
+        figs.append(fig)
+
+    if not figs:
+        print("No data found. Use --amp/--noamp or --data.")
+        sys.exit(1)
+
+    plt.show()
+
+
+if __name__ == "__main__":
+    main()

9_Firmware/9_3_GUI/radar_dashboard.py

@@ -97,6 +97,11 @@ class RadarDashboard:
         self.frame_queue: queue.Queue[RadarFrame] = queue.Queue(maxsize=8)
         self._acq_thread: RadarAcquisition | None = None
 
+        # Thread-safe UI message queue — avoids calling root.after() from
+        # background threads which crashes Python 3.12 (GIL state corruption).
+        # Entries are (tag, payload) tuples drained by _schedule_update().
+        self._ui_queue: queue.Queue[tuple[str, object]] = queue.Queue()
+
         # Display state
         self._current_frame = RadarFrame()
         self._waterfall = deque(maxlen=WATERFALL_DEPTH)
@@ -111,6 +116,16 @@ class RadarDashboard:
         self._vmax_ema = 1000.0
         self._vmax_alpha = 0.15  # smoothing factor (lower = more stable)
 
+        # AGC visualization history (ring buffers, ~60s at 10 Hz)
+        self._agc_history_len = 256
+        self._agc_gain_history: deque[int] = deque(maxlen=self._agc_history_len)
+        self._agc_peak_history: deque[int] = deque(maxlen=self._agc_history_len)
+        self._agc_sat_history: deque[int] = deque(maxlen=self._agc_history_len)
+        self._agc_time_history: deque[float] = deque(maxlen=self._agc_history_len)
+        self._agc_t0: float = time.time()
+        self._agc_last_redraw: float = 0.0  # throttle chart redraws
+        self._AGC_REDRAW_INTERVAL: float = 0.5  # seconds between redraws
+
         self._build_ui()
         self._schedule_update()
 
@@ -162,13 +177,16 @@ class RadarDashboard:
 
         tab_display = ttk.Frame(nb)
         tab_control = ttk.Frame(nb)
+        tab_agc = ttk.Frame(nb)
         tab_log = ttk.Frame(nb)
         nb.add(tab_display, text="  Display  ")
         nb.add(tab_control, text="  Control  ")
+        nb.add(tab_agc, text="  AGC Monitor  ")
         nb.add(tab_log, text="  Log  ")
 
         self._build_display_tab(tab_display)
         self._build_control_tab(tab_control)
+        self._build_agc_tab(tab_agc)
         self._build_log_tab(tab_log)
 
     def _build_display_tab(self, parent):
@@ -379,6 +397,44 @@ class RadarDashboard:
                    command=lambda: self._send_cmd(0x25, 0)).pack(
                        side="left", expand=True, fill="x", padx=(2, 0))
 
+        # ── AGC (Automatic Gain Control) ──────────────────────────────
+        grp_agc = ttk.LabelFrame(right, text="AGC (Auto Gain)", padding=10)
+        grp_agc.pack(fill="x", pady=(0, 8))
+
+        agc_params = [
+            ("AGC Enable",   0x28, "0",   1, "0=manual, 1=auto"),
+            ("AGC Target",   0x29, "200", 8, "0-255, peak target"),
+            ("AGC Attack",   0x2A, "1",   4, "0-15, atten step"),
+            ("AGC Decay",    0x2B, "1",   4, "0-15, gain-up step"),
+            ("AGC Holdoff",  0x2C, "4",   4, "0-15, frames"),
+        ]
+        for label, opcode, default, bits, hint in agc_params:
+            self._add_param_row(grp_agc, label, opcode, default, bits, hint)
+
+        # AGC quick toggle
+        agc_row = ttk.Frame(grp_agc)
+        agc_row.pack(fill="x", pady=2)
+        ttk.Button(agc_row, text="Enable AGC",
+                   command=lambda: self._send_cmd(0x28, 1)).pack(
+                       side="left", expand=True, fill="x", padx=(0, 2))
+        ttk.Button(agc_row, text="Disable AGC",
+                   command=lambda: self._send_cmd(0x28, 0)).pack(
+                       side="left", expand=True, fill="x", padx=(2, 0))
+
+        # AGC status readback labels
+        agc_st = ttk.LabelFrame(grp_agc, text="AGC Status", padding=6)
+        agc_st.pack(fill="x", pady=(4, 0))
+        self._agc_labels = {}
+        for name, default_text in [
+            ("enable", "AGC: --"),
+            ("gain",   "Gain: --"),
+            ("peak",   "Peak: --"),
+            ("sat",    "Sat Count: --"),
+        ]:
+            lbl = ttk.Label(agc_st, text=default_text, font=("Menlo", 9))
+            lbl.pack(anchor="w")
+            self._agc_labels[name] = lbl
+
         # ── Custom Command (advanced / debug) ─────────────────────────
         grp_cust = ttk.LabelFrame(right, text="Custom Command", padding=10)
         grp_cust.pack(fill="x", pady=(0, 8))
@@ -436,13 +492,98 @@ class RadarDashboard:
             var.set(str(clamped))
         self._send_cmd(opcode, clamped)
 
+    def _build_agc_tab(self, parent):
+        """AGC Monitor tab — real-time strip charts for gain, peak, and saturation."""
+        # Top row: AGC status badge + saturation indicator
+        top = ttk.Frame(parent)
+        top.pack(fill="x", padx=8, pady=(8, 0))
+
+        self._agc_badge = ttk.Label(
+            top, text="AGC: --", font=("Menlo", 14, "bold"), foreground=FG)
+        self._agc_badge.pack(side="left", padx=(0, 24))
+
+        self._agc_sat_badge = ttk.Label(
+            top, text="Saturation: 0", font=("Menlo", 12), foreground=GREEN)
+        self._agc_sat_badge.pack(side="left", padx=(0, 24))
+
+        self._agc_gain_value = ttk.Label(
+            top, text="Gain: --", font=("Menlo", 12), foreground=ACCENT)
+        self._agc_gain_value.pack(side="left", padx=(0, 24))
+
+        self._agc_peak_value = ttk.Label(
+            top, text="Peak: --", font=("Menlo", 12), foreground=ACCENT)
+        self._agc_peak_value.pack(side="left")
+
+        # Matplotlib figure with 3 stacked subplots sharing x-axis (time)
+        self._agc_fig = Figure(figsize=(14, 7), facecolor=BG)
+        self._agc_fig.subplots_adjust(
+            left=0.07, right=0.98, top=0.95, bottom=0.08,
+            hspace=0.30)
+
+        # Subplot 1: FPGA inner-loop gain (4-bit, 0-15)
+        self._ax_gain = self._agc_fig.add_subplot(3, 1, 1)
+        self._ax_gain.set_facecolor(BG2)
+        self._ax_gain.set_title("FPGA AGC Gain (inner loop)", color=FG, fontsize=10)
+        self._ax_gain.set_ylabel("Gain Level", color=FG)
+        self._ax_gain.set_ylim(-0.5, 15.5)
+        self._ax_gain.tick_params(colors=FG)
+        self._ax_gain.set_xlim(0, self._agc_history_len)
+        self._gain_line, = self._ax_gain.plot(
+            [], [], color=ACCENT, linewidth=1.5, label="Gain")
+        self._ax_gain.axhline(y=0, color=RED, linewidth=0.5, alpha=0.5, linestyle="--")
+        self._ax_gain.axhline(y=15, color=RED, linewidth=0.5, alpha=0.5, linestyle="--")
+        for spine in self._ax_gain.spines.values():
+            spine.set_color(SURFACE)
+
+        # Subplot 2: Peak magnitude (8-bit, 0-255)
+        self._ax_peak = self._agc_fig.add_subplot(3, 1, 2)
+        self._ax_peak.set_facecolor(BG2)
+        self._ax_peak.set_title("Peak Magnitude", color=FG, fontsize=10)
+        self._ax_peak.set_ylabel("Peak (8-bit)", color=FG)
+        self._ax_peak.set_ylim(-5, 260)
+        self._ax_peak.tick_params(colors=FG)
+        self._ax_peak.set_xlim(0, self._agc_history_len)
+        self._peak_line, = self._ax_peak.plot(
+            [], [], color=YELLOW, linewidth=1.5, label="Peak")
+        # AGC target reference line (default 200)
+        self._agc_target_line = self._ax_peak.axhline(
+            y=200, color=GREEN, linewidth=1.0, alpha=0.7, linestyle="--",
+            label="Target (200)")
+        self._ax_peak.legend(loc="upper right", fontsize=8,
+                             facecolor=BG2, edgecolor=SURFACE,
+                             labelcolor=FG)
+        for spine in self._ax_peak.spines.values():
+            spine.set_color(SURFACE)
+
+        # Subplot 3: Saturation count (8-bit, 0-255) as bar-style fill
+        self._ax_sat = self._agc_fig.add_subplot(3, 1, 3)
+        self._ax_sat.set_facecolor(BG2)
+        self._ax_sat.set_title("Saturation Count", color=FG, fontsize=10)
+        self._ax_sat.set_ylabel("Sat Count", color=FG)
+        self._ax_sat.set_xlabel("Sample Index", color=FG)
+        self._ax_sat.set_ylim(-1, 40)
+        self._ax_sat.tick_params(colors=FG)
+        self._ax_sat.set_xlim(0, self._agc_history_len)
+        self._sat_fill = self._ax_sat.fill_between(
+            [], [], color=RED, alpha=0.6, label="Saturation")
+        self._sat_line, = self._ax_sat.plot(
+            [], [], color=RED, linewidth=1.0)
+        self._ax_sat.axhline(y=0, color=GREEN, linewidth=0.5, alpha=0.5, linestyle="--")
+        for spine in self._ax_sat.spines.values():
+            spine.set_color(SURFACE)
+
+        agc_canvas = FigureCanvasTkAgg(self._agc_fig, master=parent)
+        agc_canvas.draw()
+        agc_canvas.get_tk_widget().pack(fill="both", expand=True)
+        self._agc_canvas = agc_canvas
+
     def _build_log_tab(self, parent):
         self.log_text = tk.Text(parent, bg=BG2, fg=FG, font=("Menlo", 10),
                                  insertbackground=FG, wrap="word")
         self.log_text.pack(fill="both", expand=True, padx=8, pady=8)
 
-        # Redirect log handler to text widget
-        handler = _TextHandler(self.log_text)
+        # Redirect log handler to text widget (via UI queue for thread safety)
+        handler = _TextHandler(self._ui_queue)
         handler.setFormatter(logging.Formatter("%(asctime)s [%(levelname)s] %(message)s",
                                                 datefmt="%H:%M:%S"))
         logging.getLogger().addHandler(handler)
@@ -468,8 +609,8 @@ class RadarDashboard:
 
         def _do_connect():
             ok = self.conn.open(self.device_index)
-            # Schedule UI update back on the main thread
-            self.root.after(0, lambda: self._on_connect_done(ok))
+            # Post result to UI queue (drained by _schedule_update)
+            self._ui_queue.put(("connect", ok))
 
         threading.Thread(target=_do_connect, daemon=True).start()
 
@@ -517,11 +658,11 @@ class RadarDashboard:
             log.error("Invalid custom command values")
 
     def _on_status_received(self, status: StatusResponse):
-        """Called from acquisition thread — schedule UI update on main thread."""
-        self.root.after(0, self._update_self_test_labels, status)
+        """Called from acquisition thread — post to UI queue for main thread."""
+        self._ui_queue.put(("status", status))
 
     def _update_self_test_labels(self, status: StatusResponse):
-        """Update the self-test result labels from a StatusResponse."""
+        """Update the self-test result labels and AGC status from a StatusResponse."""
         if not hasattr(self, '_st_labels'):
             return
         flags = status.self_test_flags
@@ -556,11 +697,124 @@ class RadarDashboard:
             self._st_labels[key].config(
                 text=f"{name}: {result_str}", foreground=color)
 
+        # AGC status readback
+        if hasattr(self, '_agc_labels'):
+            agc_str = "AUTO" if status.agc_enable else "MANUAL"
+            agc_color = GREEN if status.agc_enable else FG
+            self._agc_labels["enable"].config(
+                text=f"AGC: {agc_str}", foreground=agc_color)
+            self._agc_labels["gain"].config(
+                text=f"Gain: {status.agc_current_gain}")
+            self._agc_labels["peak"].config(
+                text=f"Peak: {status.agc_peak_magnitude}")
+            sat_color = RED if status.agc_saturation_count > 0 else FG
+            self._agc_labels["sat"].config(
+                text=f"Sat Count: {status.agc_saturation_count}",
+                foreground=sat_color)
+
+        # AGC visualization update
+        self._update_agc_visualization(status)
+
+    def _update_agc_visualization(self, status: StatusResponse):
+        """Push AGC metrics into ring buffers and redraw strip charts.
+
+        Data is always accumulated (cheap), but matplotlib redraws are
+        throttled to ``_AGC_REDRAW_INTERVAL`` seconds to avoid saturating
+        the GUI event-loop when status packets arrive at 20 Hz.
+        """
+        if not hasattr(self, '_agc_canvas'):
+            return
+
+        # Append to ring buffers (always — this is O(1))
+        self._agc_gain_history.append(status.agc_current_gain)
+        self._agc_peak_history.append(status.agc_peak_magnitude)
+        self._agc_sat_history.append(status.agc_saturation_count)
+
+        # Update indicator labels (cheap Tk config calls)
+        mode_str = "AUTO" if status.agc_enable else "MANUAL"
+        mode_color = GREEN if status.agc_enable else FG
+        self._agc_badge.config(text=f"AGC: {mode_str}", foreground=mode_color)
+        self._agc_gain_value.config(
+            text=f"Gain: {status.agc_current_gain}")
+        self._agc_peak_value.config(
+            text=f"Peak: {status.agc_peak_magnitude}")
+
+        total_sat = sum(self._agc_sat_history)
+        if total_sat > 10:
+            sat_color = RED
+        elif total_sat > 0:
+            sat_color = YELLOW
+        else:
+            sat_color = GREEN
+        self._agc_sat_badge.config(
+            text=f"Saturation: {total_sat}", foreground=sat_color)
+
+        # ---- Throttle matplotlib redraws ---------------------------------
+        now = time.monotonic()
+        if now - self._agc_last_redraw < self._AGC_REDRAW_INTERVAL:
+            return
+        self._agc_last_redraw = now
+
+        n = len(self._agc_gain_history)
+        xs = list(range(n))
+
+        # Update line plots
+        gain_data = list(self._agc_gain_history)
+        peak_data = list(self._agc_peak_history)
+        sat_data = list(self._agc_sat_history)
+
+        self._gain_line.set_data(xs, gain_data)
+        self._peak_line.set_data(xs, peak_data)
+
+        # Saturation: redraw as filled area
+        self._sat_line.set_data(xs, sat_data)
+        if self._sat_fill is not None:
+            self._sat_fill.remove()
+        self._sat_fill = self._ax_sat.fill_between(
+            xs, sat_data, color=RED, alpha=0.4)
+
+        # Auto-scale saturation Y axis to data
+        max_sat = max(sat_data) if sat_data else 0
+        self._ax_sat.set_ylim(-1, max(max_sat * 1.5, 5))
+
+        # Scroll X axis to keep latest data visible
+        if n >= self._agc_history_len:
+            self._ax_gain.set_xlim(0, n)
+            self._ax_peak.set_xlim(0, n)
+            self._ax_sat.set_xlim(0, n)
+
+        self._agc_canvas.draw_idle()
+
     # --------------------------------------------------------- Display loop
     def _schedule_update(self):
+        self._drain_ui_queue()
         self._update_display()
         self.root.after(self.UPDATE_INTERVAL_MS, self._schedule_update)
 
+    def _drain_ui_queue(self):
+        """Process all pending cross-thread messages on the main thread."""
+        while True:
+            try:
+                tag, payload = self._ui_queue.get_nowait()
+            except queue.Empty:
+                break
+            if tag == "connect":
+                self._on_connect_done(payload)
+            elif tag == "status":
+                self._update_self_test_labels(payload)
+            elif tag == "log":
+                self._log_handler_append(payload)
+
+    def _log_handler_append(self, msg: str):
+        """Append a log message to the log Text widget (main thread only)."""
+        with contextlib.suppress(Exception):
+            self.log_text.insert("end", msg + "\n")
+            self.log_text.see("end")
+            # Keep last 500 lines
+            lines = int(self.log_text.index("end-1c").split(".")[0])
+            if lines > 500:
+                self.log_text.delete("1.0", f"{lines - 500}.0")
+
     def _update_display(self):
         """Pull latest frame from queue and update plots."""
         frame = None
@@ -625,24 +879,21 @@ class RadarDashboard:
 
 
 class _TextHandler(logging.Handler):
-    """Logging handler that writes to a tkinter Text widget."""
+    """Logging handler that posts messages to a queue for main-thread append.
 
-    def __init__(self, text_widget: tk.Text):
+    Using widget.after() from background threads crashes Python 3.12 due to
+    GIL state corruption.  Instead we post to the dashboard's _ui_queue and
+    let _drain_ui_queue() append on the main thread.
+    """
+
+    def __init__(self, ui_queue: queue.Queue[tuple[str, object]]):
         super().__init__()
-        self._text = text_widget
+        self._ui_queue = ui_queue
 
     def emit(self, record):
         msg = self.format(record)
         with contextlib.suppress(Exception):
-            self._text.after(0, self._append, msg)
-
-    def _append(self, msg: str):
-        self._text.insert("end", msg + "\n")
-        self._text.see("end")
-        # Keep last 500 lines
-        lines = int(self._text.index("end-1c").split(".")[0])
-        if lines > 500:
-            self._text.delete("1.0", f"{lines - 500}.0")
+            self._ui_queue.put(("log", msg))
 
 
 # ============================================================================

9_Firmware/9_3_GUI/radar_protocol.py

@@ -59,9 +59,9 @@ class Opcode(IntEnum):
         0x03  host_detect_threshold  0x16  host_gain_shift
         0x04  host_stream_control    0x20  host_range_mode
         0x10  host_long_chirp_cycles 0x21-0x27  CFAR / MTI / DC-notch
-        0x11  host_long_listen_cycles 0x30  host_self_test_trigger
-        0x12  host_guard_cycles      0x31  host_status_request
-        0x13  host_short_chirp_cycles 0xFF  host_status_request
+        0x11  host_long_listen_cycles 0x28-0x2C  AGC control
+        0x12  host_guard_cycles      0x30  host_self_test_trigger
+        0x13  host_short_chirp_cycles 0x31/0xFF  host_status_request
     """
     # --- Basic control (0x01-0x04) ---
     RADAR_MODE          = 0x01  # 2-bit mode select
@@ -90,6 +90,13 @@ class Opcode(IntEnum):
     MTI_ENABLE          = 0x26
     DC_NOTCH_WIDTH      = 0x27
 
+    # --- AGC (0x28-0x2C) ---
+    AGC_ENABLE          = 0x28
+    AGC_TARGET          = 0x29
+    AGC_ATTACK          = 0x2A
+    AGC_DECAY           = 0x2B
+    AGC_HOLDOFF         = 0x2C
+
     # --- Board self-test / status (0x30-0x31, 0xFF) ---
     SELF_TEST_TRIGGER   = 0x30
     SELF_TEST_STATUS    = 0x31
@@ -135,6 +142,11 @@ class StatusResponse:
     self_test_flags: int = 0     # 5-bit result flags [4:0]
     self_test_detail: int = 0    # 8-bit detail code [7:0]
     self_test_busy: int = 0      # 1-bit busy flag
+    # AGC metrics (word 4, added for hybrid AGC)
+    agc_current_gain: int = 0    # 4-bit current gain encoding [3:0]
+    agc_peak_magnitude: int = 0  # 8-bit peak magnitude [7:0]
+    agc_saturation_count: int = 0  # 8-bit saturation count [7:0]
+    agc_enable: int = 0          # 1-bit AGC enable readback
 
 
 # ============================================================================
@@ -232,8 +244,13 @@ class RadarProtocol:
         # Word 3: {short_listen[31:16], 10'd0, chirps_per_elev[5:0]}
         sr.chirps_per_elev = words[3] & 0x3F
         sr.short_listen = (words[3] >> 16) & 0xFFFF
-        # Word 4: {30'd0, range_mode[1:0]}
+        # Word 4: {agc_current_gain[31:28], agc_peak_magnitude[27:20],
+        #          agc_saturation_count[19:12], agc_enable[11], 9'd0, range_mode[1:0]}
         sr.range_mode = words[4] & 0x03
+        sr.agc_enable = (words[4] >> 11) & 0x01
+        sr.agc_saturation_count = (words[4] >> 12) & 0xFF
+        sr.agc_peak_magnitude = (words[4] >> 20) & 0xFF
+        sr.agc_current_gain = (words[4] >> 28) & 0x0F
         # Word 5: {7'd0, self_test_busy, 8'd0, self_test_detail[7:0],
         #           3'd0, self_test_flags[4:0]}
         sr.self_test_flags = words[5] & 0x1F
@@ -435,7 +452,7 @@ class FT2232HConnection:
 _HARDWARE_ONLY_OPCODES = {
     0x01,  # RADAR_MODE
     0x02,  # TRIGGER_PULSE
-    0x03,  # DETECT_THRESHOLD
+    # 0x03 (DETECT_THRESHOLD) is NOT hardware-only — it's in _REPLAY_ADJUSTABLE_OPCODES
     0x04,  # STREAM_CONTROL
     0x10,  # LONG_CHIRP
     0x11,  # LONG_LISTEN
@@ -445,6 +462,11 @@ _HARDWARE_ONLY_OPCODES = {
     0x15,  # CHIRPS_PER_ELEV
     0x16,  # GAIN_SHIFT
     0x20,  # RANGE_MODE
+    0x28,  # AGC_ENABLE
+    0x29,  # AGC_TARGET
+    0x2A,  # AGC_ATTACK
+    0x2B,  # AGC_DECAY
+    0x2C,  # AGC_HOLDOFF
     0x30,  # SELF_TEST_TRIGGER
     0x31,  # SELF_TEST_STATUS
     0xFF,  # STATUS_REQUEST
@@ -452,6 +474,7 @@ _HARDWARE_ONLY_OPCODES = {
 
 # Replay-adjustable opcodes (re-run signal processing)
 _REPLAY_ADJUSTABLE_OPCODES = {
+    0x03,  # DETECT_THRESHOLD
     0x21,  # CFAR_GUARD
     0x22,  # CFAR_TRAIN
     0x23,  # CFAR_ALPHA
@@ -595,6 +618,7 @@ class ReplayConnection:
         self._cfar_alpha: int = 0x30
         self._cfar_mode: int = 0  # 0=CA, 1=GO, 2=SO
         self._cfar_enable: bool = True
+        self._detect_threshold: int = 10000  # RTL default (host_detect_threshold)
         # Raw source arrays (loaded once, reprocessed on param change)
         self._dop_mti_i: np.ndarray | None = None
         self._dop_mti_q: np.ndarray | None = None
@@ -616,7 +640,7 @@ class ReplayConnection:
                      f"(MTI={'ON' if self._mti_enable else 'OFF'}, "
                      f"{self._frame_len} bytes/frame)")
             return True
-        except (OSError, ValueError, struct.error) as e:
+        except (OSError, ValueError, IndexError, struct.error) as e:
             log.error(f"Replay open failed: {e}")
             return False
 
@@ -659,7 +683,11 @@ class ReplayConnection:
         if opcode in _REPLAY_ADJUSTABLE_OPCODES:
             changed = False
             with self._lock:
-                if opcode == 0x21:  # CFAR_GUARD
+                if opcode == 0x03:  # DETECT_THRESHOLD
+                    if self._detect_threshold != value:
+                        self._detect_threshold = value
+                        changed = True
+                elif opcode == 0x21:  # CFAR_GUARD
                     if self._cfar_guard != value:
                         self._cfar_guard = value
                         changed = True
@@ -751,7 +779,10 @@ class ReplayConnection:
                 mode=self._cfar_mode,
             )
         else:
-            det = np.zeros((NUM_RANGE_BINS, NUM_DOPPLER_BINS), dtype=bool)
+            # Simple threshold fallback matching RTL cfar_ca.v:
+            # detect = (|I| + |Q|) > detect_threshold  (L1 norm)
+            mag = np.abs(dop_i) + np.abs(dop_q)
+            det = mag > self._detect_threshold
 
         det_count = int(det.sum())
         log.info(f"Replay: rebuilt {NUM_CELLS} packets ("

9_Firmware/9_3_GUI/test_radar_dashboard.py

@@ -125,7 +125,8 @@ class TestRadarProtocol(unittest.TestCase):
                             long_chirp=3000, long_listen=13700,
                             guard=17540, short_chirp=50,
                             short_listen=17450, chirps=32, range_mode=0,
-                            st_flags=0, st_detail=0, st_busy=0):
+                            st_flags=0, st_detail=0, st_busy=0,
+                            agc_gain=0, agc_peak=0, agc_sat=0, agc_enable=0):
         """Build a 26-byte status response matching FPGA format (Build 26)."""
         pkt = bytearray()
         pkt.append(STATUS_HEADER_BYTE)
@@ -146,8 +147,11 @@ class TestRadarProtocol(unittest.TestCase):
         w3 = ((short_listen & 0xFFFF) << 16) | (chirps & 0x3F)
         pkt += struct.pack(">I", w3)
 
-        # Word 4: {30'd0, range_mode[1:0]}
-        w4 = range_mode & 0x03
+        # Word 4: {agc_current_gain[3:0], agc_peak_magnitude[7:0],
+        #          agc_saturation_count[7:0], agc_enable, 9'd0, range_mode[1:0]}
+        w4 = (((agc_gain & 0x0F) << 28) | ((agc_peak & 0xFF) << 20) |
+              ((agc_sat & 0xFF) << 12) | ((agc_enable & 0x01) << 11) |
+              (range_mode & 0x03))
         pkt += struct.pack(">I", w4)
 
         # Word 5: {7'd0, self_test_busy, 8'd0, self_test_detail[7:0],
@@ -723,6 +727,7 @@ class TestOpcodeEnum(unittest.TestCase):
         expected = {0x01, 0x02, 0x03, 0x04,
                     0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16,
                     0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
+                    0x28, 0x29, 0x2A, 0x2B, 0x2C,
                     0x30, 0x31, 0xFF}
         enum_values = {int(m) for m in Opcode}
         for op in expected:
@@ -747,5 +752,199 @@ class TestStatusResponseDefaults(unittest.TestCase):
         self.assertEqual(sr.self_test_busy, 1)
 
 
+class TestAGCOpcodes(unittest.TestCase):
+    """Verify AGC opcode enum members match FPGA RTL (0x28-0x2C)."""
+
+    def test_agc_enable_opcode(self):
+        self.assertEqual(Opcode.AGC_ENABLE, 0x28)
+
+    def test_agc_target_opcode(self):
+        self.assertEqual(Opcode.AGC_TARGET, 0x29)
+
+    def test_agc_attack_opcode(self):
+        self.assertEqual(Opcode.AGC_ATTACK, 0x2A)
+
+    def test_agc_decay_opcode(self):
+        self.assertEqual(Opcode.AGC_DECAY, 0x2B)
+
+    def test_agc_holdoff_opcode(self):
+        self.assertEqual(Opcode.AGC_HOLDOFF, 0x2C)
+
+
+class TestAGCStatusParsing(unittest.TestCase):
+    """Verify AGC fields in status_words[4] are parsed correctly."""
+
+    def _make_status_packet(self, **kwargs):
+        """Delegate to TestRadarProtocol helper."""
+        helper = TestRadarProtocol()
+        return helper._make_status_packet(**kwargs)
+
+    def test_agc_fields_default_zero(self):
+        """With no AGC fields set, all should be 0."""
+        raw = self._make_status_packet()
+        sr = RadarProtocol.parse_status_packet(raw)
+        self.assertEqual(sr.agc_current_gain, 0)
+        self.assertEqual(sr.agc_peak_magnitude, 0)
+        self.assertEqual(sr.agc_saturation_count, 0)
+        self.assertEqual(sr.agc_enable, 0)
+
+    def test_agc_fields_nonzero(self):
+        """AGC fields round-trip through status packet."""
+        raw = self._make_status_packet(agc_gain=7, agc_peak=200,
+                                       agc_sat=15, agc_enable=1)
+        sr = RadarProtocol.parse_status_packet(raw)
+        self.assertEqual(sr.agc_current_gain, 7)
+        self.assertEqual(sr.agc_peak_magnitude, 200)
+        self.assertEqual(sr.agc_saturation_count, 15)
+        self.assertEqual(sr.agc_enable, 1)
+
+    def test_agc_max_values(self):
+        """AGC fields at max values."""
+        raw = self._make_status_packet(agc_gain=15, agc_peak=255,
+                                       agc_sat=255, agc_enable=1)
+        sr = RadarProtocol.parse_status_packet(raw)
+        self.assertEqual(sr.agc_current_gain, 15)
+        self.assertEqual(sr.agc_peak_magnitude, 255)
+        self.assertEqual(sr.agc_saturation_count, 255)
+        self.assertEqual(sr.agc_enable, 1)
+
+    def test_agc_and_range_mode_coexist(self):
+        """AGC fields and range_mode occupy the same word without conflict."""
+        raw = self._make_status_packet(agc_gain=5, agc_peak=128,
+                                       agc_sat=42, agc_enable=1,
+                                       range_mode=2)
+        sr = RadarProtocol.parse_status_packet(raw)
+        self.assertEqual(sr.agc_current_gain, 5)
+        self.assertEqual(sr.agc_peak_magnitude, 128)
+        self.assertEqual(sr.agc_saturation_count, 42)
+        self.assertEqual(sr.agc_enable, 1)
+        self.assertEqual(sr.range_mode, 2)
+
+
+class TestAGCStatusResponseDefaults(unittest.TestCase):
+    """Verify StatusResponse AGC field defaults."""
+
+    def test_default_agc_fields(self):
+        sr = StatusResponse()
+        self.assertEqual(sr.agc_current_gain, 0)
+        self.assertEqual(sr.agc_peak_magnitude, 0)
+        self.assertEqual(sr.agc_saturation_count, 0)
+        self.assertEqual(sr.agc_enable, 0)
+
+    def test_agc_fields_set(self):
+        sr = StatusResponse(agc_current_gain=7, agc_peak_magnitude=200,
+                            agc_saturation_count=15, agc_enable=1)
+        self.assertEqual(sr.agc_current_gain, 7)
+        self.assertEqual(sr.agc_peak_magnitude, 200)
+        self.assertEqual(sr.agc_saturation_count, 15)
+        self.assertEqual(sr.agc_enable, 1)
+
+
+# =============================================================================
+# AGC Visualization — ring buffer / data model tests
+# =============================================================================
+
+class TestAGCVisualizationHistory(unittest.TestCase):
+    """Test the AGC visualization ring buffer logic (no GUI required)."""
+
+    def _make_deque(self, maxlen=256):
+        from collections import deque
+        return deque(maxlen=maxlen)
+
+    def test_ring_buffer_maxlen(self):
+        """Ring buffer should evict oldest when full."""
+        d = self._make_deque(maxlen=4)
+        for i in range(6):
+            d.append(i)
+        self.assertEqual(list(d), [2, 3, 4, 5])
+        self.assertEqual(len(d), 4)
+
+    def test_gain_history_accumulation(self):
+        """Gain values accumulate correctly in a deque."""
+        gain_hist = self._make_deque(maxlen=256)
+        statuses = [
+            StatusResponse(agc_current_gain=g)
+            for g in [0, 3, 7, 15, 8, 2]
+        ]
+        for st in statuses:
+            gain_hist.append(st.agc_current_gain)
+        self.assertEqual(list(gain_hist), [0, 3, 7, 15, 8, 2])
+
+    def test_peak_history_accumulation(self):
+        """Peak magnitude values accumulate correctly."""
+        peak_hist = self._make_deque(maxlen=256)
+        for p in [0, 50, 200, 255, 128]:
+            peak_hist.append(p)
+        self.assertEqual(list(peak_hist), [0, 50, 200, 255, 128])
+
+    def test_saturation_total_computation(self):
+        """Sum of saturation ring buffer gives running total."""
+        sat_hist = self._make_deque(maxlen=256)
+        for s in [0, 0, 5, 0, 12, 3]:
+            sat_hist.append(s)
+        self.assertEqual(sum(sat_hist), 20)
+
+    def test_saturation_color_thresholds(self):
+        """Color logic: green=0, yellow=1-10, red>10."""
+        def sat_color(total):
+            if total > 10:
+                return "red"
+            if total > 0:
+                return "yellow"
+            return "green"
+        self.assertEqual(sat_color(0), "green")
+        self.assertEqual(sat_color(1), "yellow")
+        self.assertEqual(sat_color(10), "yellow")
+        self.assertEqual(sat_color(11), "red")
+        self.assertEqual(sat_color(255), "red")
+
+    def test_ring_buffer_eviction_preserves_latest(self):
+        """After overflow, only the most recent values remain."""
+        d = self._make_deque(maxlen=8)
+        for i in range(20):
+            d.append(i)
+        self.assertEqual(list(d), [12, 13, 14, 15, 16, 17, 18, 19])
+
+    def test_empty_history_safe(self):
+        """Empty ring buffer should be safe for max/sum."""
+        d = self._make_deque(maxlen=256)
+        self.assertEqual(sum(d), 0)
+        self.assertEqual(len(d), 0)
+        # max() on empty would raise — test the guard pattern used in viz code
+        max_sat = max(d) if d else 0
+        self.assertEqual(max_sat, 0)
+
+    def test_agc_mode_string(self):
+        """AGC mode display string from enable flag."""
+        self.assertEqual(
+            "AUTO" if StatusResponse(agc_enable=1).agc_enable else "MANUAL",
+            "AUTO")
+        self.assertEqual(
+            "AUTO" if StatusResponse(agc_enable=0).agc_enable else "MANUAL",
+            "MANUAL")
+
+    def test_xlim_scroll_logic(self):
+        """X-axis scroll: when n >= history_len, xlim should expand."""
+        history_len = 8
+        d = self._make_deque(maxlen=history_len)
+        for i in range(10):
+            d.append(i)
+        n = len(d)
+        # After 10 pushes into maxlen=8, n=8
+        self.assertEqual(n, history_len)
+        # xlim should be (0, n) for static or (n-history_len, n) for scrolling
+        self.assertEqual(max(0, n - history_len), 0)
+        self.assertEqual(n, 8)
+
+    def test_sat_autoscale_ylim(self):
+        """Saturation y-axis auto-scale: max(max_sat * 1.5, 5)."""
+        # No saturation
+        self.assertEqual(max(0 * 1.5, 5), 5)
+        # Some saturation
+        self.assertAlmostEqual(max(10 * 1.5, 5), 15.0)
+        # High saturation
+        self.assertAlmostEqual(max(200 * 1.5, 5), 300.0)
+
+
 if __name__ == "__main__":
     unittest.main(verbosity=2)

9_Firmware/9_3_GUI/test_v7.py

@@ -334,6 +334,73 @@ class TestV7Init(unittest.TestCase):
             self.assertTrue(hasattr(v7, name), f"v7 missing export: {name}")
 
 
+# =============================================================================
+# Test: AGC Visualization data model
+# =============================================================================
+
+class TestAGCVisualizationV7(unittest.TestCase):
+    """AGC visualization ring buffer and data model tests (no Qt required)."""
+
+    def _make_deque(self, maxlen=256):
+        from collections import deque
+        return deque(maxlen=maxlen)
+
+    def test_ring_buffer_basics(self):
+        d = self._make_deque(maxlen=4)
+        for i in range(6):
+            d.append(i)
+        self.assertEqual(list(d), [2, 3, 4, 5])
+
+    def test_gain_range_4bit(self):
+        """AGC gain is 4-bit (0-15)."""
+        from radar_protocol import StatusResponse
+        for g in [0, 7, 15]:
+            sr = StatusResponse(agc_current_gain=g)
+            self.assertEqual(sr.agc_current_gain, g)
+
+    def test_peak_range_8bit(self):
+        """Peak magnitude is 8-bit (0-255)."""
+        from radar_protocol import StatusResponse
+        for p in [0, 128, 255]:
+            sr = StatusResponse(agc_peak_magnitude=p)
+            self.assertEqual(sr.agc_peak_magnitude, p)
+
+    def test_saturation_accumulation(self):
+        """Saturation ring buffer sum tracks total events."""
+        sat = self._make_deque(maxlen=256)
+        for s in [0, 5, 0, 10, 3]:
+            sat.append(s)
+        self.assertEqual(sum(sat), 18)
+
+    def test_mode_label_logic(self):
+        """AGC mode string from enable field."""
+        from radar_protocol import StatusResponse
+        self.assertEqual(
+            "AUTO" if StatusResponse(agc_enable=1).agc_enable else "MANUAL",
+            "AUTO")
+        self.assertEqual(
+            "AUTO" if StatusResponse(agc_enable=0).agc_enable else "MANUAL",
+            "MANUAL")
+
+    def test_history_len_default(self):
+        """Default history length should be 256."""
+        d = self._make_deque(maxlen=256)
+        self.assertEqual(d.maxlen, 256)
+
+    def test_color_thresholds(self):
+        """Saturation color: green=0, warning=1-10, error>10."""
+        from v7.models import DARK_SUCCESS, DARK_WARNING, DARK_ERROR
+        def pick_color(total):
+            if total > 10:
+                return DARK_ERROR
+            if total > 0:
+                return DARK_WARNING
+            return DARK_SUCCESS
+        self.assertEqual(pick_color(0), DARK_SUCCESS)
+        self.assertEqual(pick_color(5), DARK_WARNING)
+        self.assertEqual(pick_color(11), DARK_ERROR)
+
+
 # =============================================================================
 # Helper: lazy import of v7.models
 # =============================================================================

9_Firmware/9_3_GUI/v7/dashboard.py

@@ -1,15 +1,16 @@
 """
 v7.dashboard — Main application window for the PLFM Radar GUI V7.
 
-RadarDashboard is a QMainWindow with five tabs:
+RadarDashboard is a QMainWindow with six tabs:
   1. Main View   — Range-Doppler matplotlib canvas (64x32), device combos,
                    Start/Stop, targets table
   2. Map View    — Embedded Leaflet map + sidebar
-  3. FPGA Control — Full FPGA register control panel (all 22 opcodes,
+  3. FPGA Control — Full FPGA register control panel (all 27 opcodes incl. AGC,
                     bit-width validation, grouped layout matching production)
-  4. Diagnostics — Connection indicators, packet stats, dependency status,
+  4. AGC Monitor — Real-time AGC strip charts (gain, peak magnitude, saturation)
+  5. Diagnostics — Connection indicators, packet stats, dependency status,
                    self-test results, log viewer
-  5. Settings    — Host-side DSP parameters + About section
+  6. Settings    — Host-side DSP parameters + About section
 
 Uses production radar_protocol.py for all FPGA communication:
   - FT2232HConnection for real hardware
@@ -23,6 +24,7 @@ commands sent over FT2232H.
 
 import time
 import logging
+from collections import deque
 
 import numpy as np
 
@@ -34,7 +36,7 @@ from PyQt6.QtWidgets import (
     QTableWidget, QTableWidgetItem, QHeaderView,
     QPlainTextEdit, QStatusBar, QMessageBox,
 )
-from PyQt6.QtCore import Qt, QTimer, pyqtSlot
+from PyQt6.QtCore import Qt, QTimer, pyqtSignal, pyqtSlot, QObject
 
 from matplotlib.backends.backend_qtagg import FigureCanvasQTAgg
 from matplotlib.figure import Figure
@@ -148,11 +150,20 @@ class RadarDashboard(QMainWindow):
         self._last_status: StatusResponse | None = None
         self._frame_count = 0
         self._gps_packet_count = 0
+        self._last_stats: dict = {}
         self._current_targets: list[RadarTarget] = []
 
         # FPGA control parameter widgets
         self._param_spins: dict = {}  # opcode_hex -> QSpinBox
 
+        # AGC visualization history (ring buffers)
+        self._agc_history_len = 256
+        self._agc_gain_history: deque[int] = deque(maxlen=self._agc_history_len)
+        self._agc_peak_history: deque[int] = deque(maxlen=self._agc_history_len)
+        self._agc_sat_history: deque[int] = deque(maxlen=self._agc_history_len)
+        self._agc_last_redraw: float = 0.0  # throttle chart redraws
+        self._AGC_REDRAW_INTERVAL: float = 0.5  # seconds between redraws
+
         # ---- Build UI ------------------------------------------------------
         self._apply_dark_theme()
         self._setup_ui()
@@ -163,8 +174,10 @@ class RadarDashboard(QMainWindow):
         self._gui_timer.timeout.connect(self._refresh_gui)
         self._gui_timer.start(100)
 
-        # Log handler for diagnostics
-        self._log_handler = _QtLogHandler(self._log_append)
+        # Log handler for diagnostics (thread-safe via Qt signal)
+        self._log_bridge = _LogSignalBridge(self)
+        self._log_bridge.log_message.connect(self._log_append)
+        self._log_handler = _QtLogHandler(self._log_bridge)
         self._log_handler.setLevel(logging.INFO)
         logging.getLogger().addHandler(self._log_handler)
 
@@ -306,6 +319,7 @@ class RadarDashboard(QMainWindow):
         self._create_main_tab()
         self._create_map_tab()
         self._create_fpga_control_tab()
+        self._create_agc_monitor_tab()
         self._create_diagnostics_tab()
         self._create_settings_tab()
 
@@ -392,7 +406,7 @@ class RadarDashboard(QMainWindow):
         self._targets_table_main = QTableWidget()
         self._targets_table_main.setColumnCount(5)
         self._targets_table_main.setHorizontalHeaderLabels([
-            "Range Bin", "Doppler Bin", "Magnitude", "SNR (dB)", "Track ID",
+            "Range (m)", "Velocity (m/s)", "Magnitude", "SNR (dB)", "Track ID",
         ])
         self._targets_table_main.setAlternatingRowColors(True)
         self._targets_table_main.setSelectionBehavior(
@@ -681,6 +695,48 @@ class RadarDashboard(QMainWindow):
 
         right_layout.addWidget(grp_cfar)
 
+        # ── AGC (Automatic Gain Control) ──────────────────────────────
+        grp_agc = QGroupBox("AGC (Auto Gain)")
+        agc_layout = QVBoxLayout(grp_agc)
+
+        agc_params = [
+            ("AGC Enable",  0x28,   0,  1, "0=manual, 1=auto"),
+            ("AGC Target",  0x29, 200,  8, "0-255, peak target"),
+            ("AGC Attack",  0x2A,   1,  4, "0-15, atten step"),
+            ("AGC Decay",   0x2B,   1,  4, "0-15, gain-up step"),
+            ("AGC Holdoff", 0x2C,   4,  4, "0-15, frames"),
+        ]
+        for label, opcode, default, bits, hint in agc_params:
+            self._add_fpga_param_row(agc_layout, label, opcode, default, bits, hint)
+
+        # AGC quick toggles
+        agc_row = QHBoxLayout()
+        btn_agc_on = QPushButton("Enable AGC")
+        btn_agc_on.clicked.connect(lambda: self._send_fpga_cmd(0x28, 1))
+        agc_row.addWidget(btn_agc_on)
+        btn_agc_off = QPushButton("Disable AGC")
+        btn_agc_off.clicked.connect(lambda: self._send_fpga_cmd(0x28, 0))
+        agc_row.addWidget(btn_agc_off)
+        agc_layout.addLayout(agc_row)
+
+        # AGC status readback labels
+        agc_st_group = QGroupBox("AGC Status")
+        agc_st_layout = QVBoxLayout(agc_st_group)
+        self._agc_labels: dict[str, QLabel] = {}
+        for name, default_text in [
+            ("enable", "AGC: --"),
+            ("gain",   "Gain: --"),
+            ("peak",   "Peak: --"),
+            ("sat",    "Sat Count: --"),
+        ]:
+            lbl = QLabel(default_text)
+            lbl.setStyleSheet(f"color: {DARK_INFO}; font-size: 10px;")
+            agc_st_layout.addWidget(lbl)
+            self._agc_labels[name] = lbl
+        agc_layout.addWidget(agc_st_group)
+
+        right_layout.addWidget(grp_agc)
+
         # Custom Command
         grp_custom = QGroupBox("Custom Command")
         cust_layout = QGridLayout(grp_custom)
@@ -741,7 +797,122 @@ class RadarDashboard(QMainWindow):
         parent_layout.addLayout(row)
 
     # -----------------------------------------------------------------
-    # TAB 4: Diagnostics
+    # TAB 4: AGC Monitor
+    # -----------------------------------------------------------------
+
+    def _create_agc_monitor_tab(self):
+        """AGC Monitor — real-time strip charts for FPGA inner-loop AGC."""
+        tab = QWidget()
+        layout = QVBoxLayout(tab)
+        layout.setContentsMargins(8, 8, 8, 8)
+
+        # ---- Top indicator row ---------------------------------------------
+        indicator = QFrame()
+        indicator.setStyleSheet(
+            f"background-color: {DARK_ACCENT}; border-radius: 4px;")
+        ind_layout = QHBoxLayout(indicator)
+        ind_layout.setContentsMargins(12, 8, 12, 8)
+
+        self._agc_mode_lbl = QLabel("AGC: --")
+        self._agc_mode_lbl.setStyleSheet(
+            f"color: {DARK_FG}; font-size: 16px; font-weight: bold;")
+        ind_layout.addWidget(self._agc_mode_lbl)
+
+        self._agc_gain_lbl = QLabel("Gain: --")
+        self._agc_gain_lbl.setStyleSheet(
+            f"color: {DARK_INFO}; font-size: 14px;")
+        ind_layout.addWidget(self._agc_gain_lbl)
+
+        self._agc_peak_lbl = QLabel("Peak: --")
+        self._agc_peak_lbl.setStyleSheet(
+            f"color: {DARK_INFO}; font-size: 14px;")
+        ind_layout.addWidget(self._agc_peak_lbl)
+
+        self._agc_sat_total_lbl = QLabel("Total Saturations: 0")
+        self._agc_sat_total_lbl.setStyleSheet(
+            f"color: {DARK_SUCCESS}; font-size: 14px; font-weight: bold;")
+        ind_layout.addWidget(self._agc_sat_total_lbl)
+
+        ind_layout.addStretch()
+        layout.addWidget(indicator)
+
+        # ---- Matplotlib figure with 3 subplots -----------------------------
+        agc_fig = Figure(figsize=(12, 7), facecolor=DARK_BG)
+        agc_fig.subplots_adjust(
+            left=0.07, right=0.96, top=0.95, bottom=0.07,
+            hspace=0.32)
+
+        # Subplot 1: Gain history (4-bit, 0-15)
+        self._agc_ax_gain = agc_fig.add_subplot(3, 1, 1)
+        self._agc_ax_gain.set_facecolor(DARK_ACCENT)
+        self._agc_ax_gain.set_ylabel("Gain Code", color=DARK_FG, fontsize=10)
+        self._agc_ax_gain.set_title(
+            "FPGA Inner-Loop Gain (4-bit)", color=DARK_FG, fontsize=11)
+        self._agc_ax_gain.set_ylim(-0.5, 15.5)
+        self._agc_ax_gain.tick_params(colors=DARK_FG, labelsize=9)
+        self._agc_ax_gain.set_xlim(0, self._agc_history_len)
+        for spine in self._agc_ax_gain.spines.values():
+            spine.set_color(DARK_BORDER)
+        self._agc_gain_line, = self._agc_ax_gain.plot(
+            [], [], color="#89b4fa", linewidth=1.5, label="Gain")
+        self._agc_ax_gain.axhline(y=7.5, color=DARK_WARNING, linestyle="--",
+                                  linewidth=0.8, alpha=0.5, label="Midpoint")
+        self._agc_ax_gain.legend(
+            loc="upper right", fontsize=8,
+            facecolor=DARK_ACCENT, edgecolor=DARK_BORDER,
+            labelcolor=DARK_FG)
+
+        # Subplot 2: Peak magnitude (8-bit, 0-255)
+        self._agc_ax_peak = agc_fig.add_subplot(
+            3, 1, 2, sharex=self._agc_ax_gain)
+        self._agc_ax_peak.set_facecolor(DARK_ACCENT)
+        self._agc_ax_peak.set_ylabel("Peak Mag", color=DARK_FG, fontsize=10)
+        self._agc_ax_peak.set_title(
+            "ADC Peak Magnitude (8-bit)", color=DARK_FG, fontsize=11)
+        self._agc_ax_peak.set_ylim(-5, 260)
+        self._agc_ax_peak.tick_params(colors=DARK_FG, labelsize=9)
+        for spine in self._agc_ax_peak.spines.values():
+            spine.set_color(DARK_BORDER)
+        self._agc_peak_line, = self._agc_ax_peak.plot(
+            [], [], color=DARK_SUCCESS, linewidth=1.5, label="Peak")
+        self._agc_ax_peak.axhline(y=200, color=DARK_WARNING, linestyle="--",
+                                  linewidth=0.8, alpha=0.5,
+                                  label="Target (200)")
+        self._agc_ax_peak.axhspan(240, 255, alpha=0.15, color=DARK_ERROR,
+                                  label="Sat Zone")
+        self._agc_ax_peak.legend(
+            loc="upper right", fontsize=8,
+            facecolor=DARK_ACCENT, edgecolor=DARK_BORDER,
+            labelcolor=DARK_FG)
+
+        # Subplot 3: Saturation count per update (8-bit, 0-255)
+        self._agc_ax_sat = agc_fig.add_subplot(
+            3, 1, 3, sharex=self._agc_ax_gain)
+        self._agc_ax_sat.set_facecolor(DARK_ACCENT)
+        self._agc_ax_sat.set_ylabel("Sat Count", color=DARK_FG, fontsize=10)
+        self._agc_ax_sat.set_xlabel(
+            "Sample (newest right)", color=DARK_FG, fontsize=10)
+        self._agc_ax_sat.set_title(
+            "Saturation Events per Update", color=DARK_FG, fontsize=11)
+        self._agc_ax_sat.set_ylim(-1, 10)
+        self._agc_ax_sat.tick_params(colors=DARK_FG, labelsize=9)
+        for spine in self._agc_ax_sat.spines.values():
+            spine.set_color(DARK_BORDER)
+        self._agc_sat_line, = self._agc_ax_sat.plot(
+            [], [], color=DARK_ERROR, linewidth=1.0)
+        self._agc_sat_fill_artist = None
+        self._agc_ax_sat.legend(
+            loc="upper right", fontsize=8,
+            facecolor=DARK_ACCENT, edgecolor=DARK_BORDER,
+            labelcolor=DARK_FG)
+
+        self._agc_canvas = FigureCanvasQTAgg(agc_fig)
+        layout.addWidget(self._agc_canvas, stretch=1)
+
+        self._tabs.addTab(tab, "AGC Monitor")
+
+    # -----------------------------------------------------------------
+    # TAB 5: Diagnostics
     # -----------------------------------------------------------------
 
     def _create_diagnostics_tab(self):
@@ -1142,7 +1313,13 @@ class RadarDashboard(QMainWindow):
             self._simulator.stop()
             self._simulator = None
         self._demo_mode = False
-        self._sb_mode.setText("Idle" if not self._running else "Live")
+        if not self._running:
+            mode = "Idle"
+        elif isinstance(self._connection, ReplayConnection):
+            mode = "Replay"
+        else:
+            mode = "Live"
+        self._sb_mode.setText(mode)
         self._sb_status.setText("Demo stopped")
         self._demo_btn_main.setText("Start Demo")
         self._demo_btn_map.setText("Start Demo")
@@ -1189,7 +1366,7 @@ class RadarDashboard(QMainWindow):
 
     @pyqtSlot(dict)
     def _on_radar_stats(self, stats: dict):
-        pass  # Stats are displayed in _refresh_gui
+        self._last_stats = stats
 
     @pyqtSlot(str)
     def _on_worker_error(self, msg: str):
@@ -1276,6 +1453,97 @@ class RadarDashboard(QMainWindow):
             self._st_labels["t4"].setText(
                 f"T4 ADC:  {'PASS' if flags & 0x10 else 'FAIL'}")
 
+        # AGC status readback
+        if hasattr(self, '_agc_labels'):
+            agc_str = "AUTO" if st.agc_enable else "MANUAL"
+            agc_color = DARK_SUCCESS if st.agc_enable else DARK_INFO
+            self._agc_labels["enable"].setStyleSheet(
+                f"color: {agc_color}; font-weight: bold;")
+            self._agc_labels["enable"].setText(f"AGC: {agc_str}")
+            self._agc_labels["gain"].setText(
+                f"Gain: {st.agc_current_gain}")
+            self._agc_labels["peak"].setText(
+                f"Peak: {st.agc_peak_magnitude}")
+            sat_color = DARK_ERROR if st.agc_saturation_count > 0 else DARK_INFO
+            self._agc_labels["sat"].setStyleSheet(
+                f"color: {sat_color}; font-weight: bold;")
+            self._agc_labels["sat"].setText(
+                f"Sat Count: {st.agc_saturation_count}")
+
+        # AGC Monitor tab visualization
+        self._update_agc_visualization(st)
+
+    def _update_agc_visualization(self, st: StatusResponse):
+        """Push AGC metrics into ring buffers and redraw AGC Monitor charts.
+
+        Data is always accumulated (cheap), but matplotlib redraws are
+        throttled to ``_AGC_REDRAW_INTERVAL`` seconds to avoid saturating
+        the GUI event-loop when status packets arrive at 20 Hz.
+        """
+        if not hasattr(self, '_agc_canvas'):
+            return
+
+        # Push data into ring buffers (always — O(1))
+        self._agc_gain_history.append(st.agc_current_gain)
+        self._agc_peak_history.append(st.agc_peak_magnitude)
+        self._agc_sat_history.append(st.agc_saturation_count)
+
+        # Update indicator labels (cheap Qt calls)
+        agc_str = "AUTO" if st.agc_enable else "MANUAL"
+        agc_color = DARK_SUCCESS if st.agc_enable else DARK_INFO
+        self._agc_mode_lbl.setStyleSheet(
+            f"color: {agc_color}; font-size: 16px; font-weight: bold;")
+        self._agc_mode_lbl.setText(f"AGC: {agc_str}")
+        self._agc_gain_lbl.setText(f"Gain: {st.agc_current_gain}")
+        self._agc_peak_lbl.setText(f"Peak: {st.agc_peak_magnitude}")
+
+        total_sat = sum(self._agc_sat_history)
+        if total_sat > 10:
+            sat_color = DARK_ERROR
+        elif total_sat > 0:
+            sat_color = DARK_WARNING
+        else:
+            sat_color = DARK_SUCCESS
+        self._agc_sat_total_lbl.setStyleSheet(
+            f"color: {sat_color}; font-size: 14px; font-weight: bold;")
+        self._agc_sat_total_lbl.setText(f"Total Saturations: {total_sat}")
+
+        # ---- Throttle matplotlib redraws ---------------------------------
+        now = time.monotonic()
+        if now - self._agc_last_redraw < self._AGC_REDRAW_INTERVAL:
+            return
+        self._agc_last_redraw = now
+
+        n = len(self._agc_gain_history)
+        xs = list(range(n))
+
+        # Update line plots
+        gain_data = list(self._agc_gain_history)
+        peak_data = list(self._agc_peak_history)
+        sat_data = list(self._agc_sat_history)
+
+        self._agc_gain_line.set_data(xs, gain_data)
+        self._agc_peak_line.set_data(xs, peak_data)
+        self._agc_sat_line.set_data(xs, sat_data)
+
+        # Update saturation fill
+        if self._agc_sat_fill_artist is not None:
+            self._agc_sat_fill_artist.remove()
+        if n > 0:
+            self._agc_sat_fill_artist = self._agc_ax_sat.fill_between(
+                xs, sat_data, color=DARK_ERROR, alpha=0.4)
+        else:
+            self._agc_sat_fill_artist = None
+
+        # Auto-scale saturation y-axis
+        max_sat = max(sat_data) if sat_data else 1
+        self._agc_ax_sat.set_ylim(-1, max(max_sat * 1.3, 5))
+
+        # Scroll x-axis
+        self._agc_ax_gain.set_xlim(max(0, n - self._agc_history_len), n)
+
+        self._agc_canvas.draw_idle()
+
     # =====================================================================
     # Position / coverage callbacks (map sidebar)
     # =====================================================================
@@ -1409,7 +1677,7 @@ class RadarDashboard(QMainWindow):
             str(self._frame_count),
             str(det),
             str(gps_count),
-            "0",  # errors
+            str(self._last_stats.get("errors", 0)),
             f"{uptime:.0f}s",
             f"{frame_rate:.1f}/s",
         ]
@@ -1460,15 +1728,22 @@ class RadarDashboard(QMainWindow):
 
 
 # =============================================================================
-# Qt-compatible log handler (routes Python logging -> QTextEdit)
+# Qt-compatible log handler (routes Python logging -> QTextEdit via signal)
 # =============================================================================
 
-class _QtLogHandler(logging.Handler):
-    """Sends log records to a callback (called on the thread that emitted)."""
 
-    def __init__(self, callback):
+class _LogSignalBridge(QObject):
+    """Thread-safe bridge: emits a Qt signal so the slot runs on the GUI thread."""
+
+    log_message = pyqtSignal(str)
+
+
+class _QtLogHandler(logging.Handler):
+    """Sends log records to a QObject signal (safe from any thread)."""
+
+    def __init__(self, bridge: _LogSignalBridge):
         super().__init__()
-        self._callback = callback
+        self._bridge = bridge
         self.setFormatter(logging.Formatter(
             "%(asctime)s  %(levelname)-8s  %(message)s",
             datefmt="%H:%M:%S",
@@ -1477,6 +1752,6 @@ class _QtLogHandler(logging.Handler):
     def emit(self, record):
         try:
             msg = self.format(record)
-            self._callback(msg)
+            self._bridge.log_message.emit(msg)
         except RuntimeError:
             pass

9_Firmware/tests/cross_layer/contract_parser.py

@@ -527,6 +527,8 @@ def parse_verilog_status_word_concats(
     ):
         idx = int(m.group(1))
         expr = m.group(2)
+        # Strip single-line comments before normalizing whitespace
+        expr = re.sub(r'//[^\n]*', '', expr)
         # Normalize whitespace
         expr = re.sub(r'\s+', ' ', expr).strip()
         results[idx] = expr

9_Firmware/tests/cross_layer/tb_cross_layer_ft2232h.v

@@ -86,6 +86,10 @@ module tb_cross_layer_ft2232h;
     reg  [4:0]  status_self_test_flags;
     reg  [7:0]  status_self_test_detail;
     reg         status_self_test_busy;
+    reg  [3:0]  status_agc_current_gain;
+    reg  [7:0]  status_agc_peak_magnitude;
+    reg  [7:0]  status_agc_saturation_count;
+    reg         status_agc_enable;
 
     // ---- Clock generators ----
     always #(CLK_PERIOD / 2)    clk    = ~clk;
@@ -130,7 +134,11 @@ module tb_cross_layer_ft2232h;
         .status_range_mode      (status_range_mode),
         .status_self_test_flags (status_self_test_flags),
         .status_self_test_detail(status_self_test_detail),
-        .status_self_test_busy  (status_self_test_busy)
+        .status_self_test_busy  (status_self_test_busy),
+        .status_agc_current_gain    (status_agc_current_gain),
+        .status_agc_peak_magnitude  (status_agc_peak_magnitude),
+        .status_agc_saturation_count(status_agc_saturation_count),
+        .status_agc_enable          (status_agc_enable)
     );
 
     // ---- Test bookkeeping ----
@@ -188,6 +196,10 @@ module tb_cross_layer_ft2232h;
             status_self_test_flags  = 5'b00000;
             status_self_test_detail = 8'd0;
             status_self_test_busy   = 1'b0;
+            status_agc_current_gain     = 4'd0;
+            status_agc_peak_magnitude   = 8'd0;
+            status_agc_saturation_count = 8'd0;
+            status_agc_enable           = 1'b0;
             repeat (6) @(posedge ft_clk);
             reset_n    = 1;
             ft_reset_n = 1;
@@ -492,6 +504,37 @@ module tb_cross_layer_ft2232h;
         check(cmd_opcode === 8'h27 && cmd_value === 16'h0003,
               "Cmd 0x27: DC_NOTCH_WIDTH=3");
 
+        // AGC registers (0x28-0x2C)
+        send_command_ft2232h(8'h28, 8'h00, 8'h00, 8'h01);  // AGC_ENABLE=1
+        $fwrite(cmd_file, "%02x %02x %04x %02x %02x %04x\n",
+                8'h28, 8'h00, 16'h0001, cmd_opcode, cmd_addr, cmd_value);
+        check(cmd_opcode === 8'h28 && cmd_value === 16'h0001,
+              "Cmd 0x28: AGC_ENABLE=1");
+
+        send_command_ft2232h(8'h29, 8'h00, 8'h00, 8'hC8);  // AGC_TARGET=200
+        $fwrite(cmd_file, "%02x %02x %04x %02x %02x %04x\n",
+                8'h29, 8'h00, 16'h00C8, cmd_opcode, cmd_addr, cmd_value);
+        check(cmd_opcode === 8'h29 && cmd_value === 16'h00C8,
+              "Cmd 0x29: AGC_TARGET=200");
+
+        send_command_ft2232h(8'h2A, 8'h00, 8'h00, 8'h02);  // AGC_ATTACK=2
+        $fwrite(cmd_file, "%02x %02x %04x %02x %02x %04x\n",
+                8'h2A, 8'h00, 16'h0002, cmd_opcode, cmd_addr, cmd_value);
+        check(cmd_opcode === 8'h2A && cmd_value === 16'h0002,
+              "Cmd 0x2A: AGC_ATTACK=2");
+
+        send_command_ft2232h(8'h2B, 8'h00, 8'h00, 8'h03);  // AGC_DECAY=3
+        $fwrite(cmd_file, "%02x %02x %04x %02x %02x %04x\n",
+                8'h2B, 8'h00, 16'h0003, cmd_opcode, cmd_addr, cmd_value);
+        check(cmd_opcode === 8'h2B && cmd_value === 16'h0003,
+              "Cmd 0x2B: AGC_DECAY=3");
+
+        send_command_ft2232h(8'h2C, 8'h00, 8'h00, 8'h06);  // AGC_HOLDOFF=6
+        $fwrite(cmd_file, "%02x %02x %04x %02x %02x %04x\n",
+                8'h2C, 8'h00, 16'h0006, cmd_opcode, cmd_addr, cmd_value);
+        check(cmd_opcode === 8'h2C && cmd_value === 16'h0006,
+              "Cmd 0x2C: AGC_HOLDOFF=6");
+
         // Self-test / status
         send_command_ft2232h(8'h30, 8'h00, 8'h00, 8'h01);  // SELF_TEST_TRIGGER
         $fwrite(cmd_file, "%02x %02x %04x %02x %02x %04x\n",
@@ -605,6 +648,10 @@ module tb_cross_layer_ft2232h;
         status_self_test_flags  = 5'b10101;
         status_self_test_detail = 8'hA5;
         status_self_test_busy   = 1'b1;
+        status_agc_current_gain     = 4'd7;
+        status_agc_peak_magnitude   = 8'd200;
+        status_agc_saturation_count = 8'd15;
+        status_agc_enable           = 1'b1;
 
         // Pulse status_request and capture bytes IN PARALLEL
         // (same reason as Exercise B — write FSM starts before CDC wait ends)

9_Firmware/tests/cross_layer/test_cross_layer_contract.py

@@ -100,6 +100,11 @@ GROUND_TRUTH_OPCODES = {
     0x25: ("host_cfar_enable", 1),
     0x26: ("host_mti_enable", 1),
     0x27: ("host_dc_notch_width", 3),
+    0x28: ("host_agc_enable", 1),
+    0x29: ("host_agc_target", 8),
+    0x2A: ("host_agc_attack", 4),
+    0x2B: ("host_agc_decay", 4),
+    0x2C: ("host_agc_holdoff", 4),
     0x30: ("host_self_test_trigger", 1),  # pulse
     0x31: ("host_status_request", 1),     # pulse
     0xFF: ("host_status_request", 1),     # alias, pulse
@@ -124,6 +129,11 @@ GROUND_TRUTH_RESET_DEFAULTS = {
     "host_cfar_enable": 0,
     "host_mti_enable": 0,
     "host_dc_notch_width": 0,
+    "host_agc_enable": 0,
+    "host_agc_target": 200,
+    "host_agc_attack": 1,
+    "host_agc_decay": 1,
+    "host_agc_holdoff": 4,
 }
 
 GROUND_TRUTH_PACKET_CONSTANTS = {
@@ -604,6 +614,10 @@ class TestTier2VerilogCosim:
         #   status_self_test_flags = 5'b10101 = 21
         #   status_self_test_detail = 0xA5
         #   status_self_test_busy = 1
+        #   status_agc_current_gain = 7
+        #   status_agc_peak_magnitude = 200
+        #   status_agc_saturation_count = 15
+        #   status_agc_enable = 1
 
         # Words 1-5 should be correct (no truncation bug)
         assert sr.cfar_threshold == 0xABCD, f"cfar_threshold: 0x{sr.cfar_threshold:04X}"
@@ -618,6 +632,12 @@ class TestTier2VerilogCosim:
         assert sr.self_test_detail == 0xA5, f"self_test_detail: 0x{sr.self_test_detail:02X}"
         assert sr.self_test_busy == 1, f"self_test_busy: {sr.self_test_busy}"
 
+        # AGC fields (word 4)
+        assert sr.agc_current_gain == 7, f"agc_current_gain: {sr.agc_current_gain}"
+        assert sr.agc_peak_magnitude == 200, f"agc_peak_magnitude: {sr.agc_peak_magnitude}"
+        assert sr.agc_saturation_count == 15, f"agc_saturation_count: {sr.agc_saturation_count}"
+        assert sr.agc_enable == 1, f"agc_enable: {sr.agc_enable}"
+
         # Word 0: stream_ctrl should be 5 (3'b101)
         assert sr.stream_ctrl == 5, (
             f"stream_ctrl: {sr.stream_ctrl} != 5. "