feat(fpga): make FT2232H default USB interface, rewrite FT601 write FSM, add clock-loss watchdog

- Set USB_MODE default to 1 (FT2232H) in radar_system_top.v; 200T build
  overrides to USB_MODE=0 via build_200t.tcl generic property
- Rewrite FT601 write FSM: 4-state architecture with 3-word packed data,
  pending-flag gating, and frame sync counter
- Add FT2232H read FSM rd_cmd_complete flag, stream field zeroing, and
  range_data_ready 1-cycle pipeline delay in both USB modules
- Implement clock-loss watchdog: ft_heartbeat toggle + 16-bit timeout
  counter drives ft_clk_lost, feeding ft_effective_reset_n via 2-stage
  ASYNC_REG synchronizer chain
- Fix sample_counter reset literal width (11'd0 -> 12'd0)
- Add FT2232H I/O timing constraints to 50T XDC; fix dac_clk comments
- Document vestigial ft601_txe_n/rxf_n ports (needed for 200T XDC)
- Tie off AGC ports on TE0713 dev wrapper
- Rewrite tb_usb_data_interface.v for new 4-state FSM (89 checks)
- Add USB_MODE=1 regression runs; remove dead CHECK 5/6 loop
- Update diag_log.h USB interface comment

9_Firmware/9_2_FPGA/run_regression.sh

@@ -70,6 +70,7 @@ PROD_RTL=(
     xfft_16.v
     fft_engine.v
     usb_data_interface.v
+    usb_data_interface_ft2232h.v
     edge_detector.v
     radar_mode_controller.v
     rx_gain_control.v
@@ -219,26 +220,9 @@ run_lint_static() {
         fi
     done
 
-    # --- Single-line regex checks across all production RTL ---
-    for f in "$@"; do
-        [[ -f "$f" ]] || continue
-        case "$f" in tb/*) continue ;; esac
-
-        local linenum=0
-        while IFS= read -r line; do
-            linenum=$((linenum + 1))
-
-            # CHECK 5: $readmemh / $readmemb in synthesizable code
-            # (Only valid in simulation blocks — flag if outside `ifdef SIMULATION)
-            # This is hard to check line-by-line without tracking ifdefs.
-            # Skip for v1.
-
-            # CHECK 6: Unused `include files (informational only)
-            # Skip for v1.
-
-            :  # placeholder — prevents empty loop body
-        done < "$f"
-    done
+    # CHECK 5 ($readmemh in synth code) and CHECK 6 (unused includes)
+    # require multi-line ifdef tracking / cross-file analysis. Not feasible
+    # with line-by-line regex. Omitted — use Vivado lint instead.
 
     if [[ "$err_count" -gt 0 ]]; then
         echo -e "${RED}FAIL${NC} ($err_count errors, $warn_count warnings)"
@@ -452,7 +436,7 @@ if [[ "$QUICK" -eq 0 ]]; then
         chirp_memory_loader_param.v latency_buffer.v \
         matched_filter_multi_segment.v matched_filter_processing_chain.v \
         range_bin_decimator.v doppler_processor.v xfft_16.v fft_engine.v \
-        usb_data_interface.v edge_detector.v radar_mode_controller.v \
+        usb_data_interface.v usb_data_interface_ft2232h.v edge_detector.v radar_mode_controller.v \
         rx_gain_control.v cfar_ca.v mti_canceller.v fpga_self_test.v
 
     # E2E integration (46 strict checks: TX, RX, USB R/W, CDC, safety, reset)
@@ -466,11 +450,40 @@ if [[ "$QUICK" -eq 0 ]]; then
         chirp_memory_loader_param.v latency_buffer.v \
         matched_filter_multi_segment.v matched_filter_processing_chain.v \
         range_bin_decimator.v doppler_processor.v xfft_16.v fft_engine.v \
-        usb_data_interface.v edge_detector.v radar_mode_controller.v \
+        usb_data_interface.v usb_data_interface_ft2232h.v edge_detector.v radar_mode_controller.v \
+        rx_gain_control.v cfar_ca.v mti_canceller.v fpga_self_test.v
+
+    # USB_MODE=1 (FT2232H production) variants of system tests
+    run_test "System Top USB_MODE=1 (FT2232H)" \
+        tb/tb_system_ft2232h_reg.vvp \
+        -DUSB_MODE_1 \
+        tb/radar_system_tb.v radar_system_top.v \
+        radar_transmitter.v dac_interface_single.v plfm_chirp_controller.v \
+        radar_receiver_final.v tb/ad9484_interface_400m_stub.v \
+        ddc_400m.v nco_400m_enhanced.v cic_decimator_4x_enhanced.v \
+        cdc_modules.v fir_lowpass.v ddc_input_interface.v \
+        chirp_memory_loader_param.v latency_buffer.v \
+        matched_filter_multi_segment.v matched_filter_processing_chain.v \
+        range_bin_decimator.v doppler_processor.v xfft_16.v fft_engine.v \
+        usb_data_interface.v usb_data_interface_ft2232h.v edge_detector.v radar_mode_controller.v \
+        rx_gain_control.v cfar_ca.v mti_canceller.v fpga_self_test.v
+
+    run_test "System E2E USB_MODE=1 (FT2232H)" \
+        tb/tb_system_e2e_ft2232h_reg.vvp \
+        -DUSB_MODE_1 \
+        tb/tb_system_e2e.v radar_system_top.v \
+        radar_transmitter.v dac_interface_single.v plfm_chirp_controller.v \
+        radar_receiver_final.v tb/ad9484_interface_400m_stub.v \
+        ddc_400m.v nco_400m_enhanced.v cic_decimator_4x_enhanced.v \
+        cdc_modules.v fir_lowpass.v ddc_input_interface.v \
+        chirp_memory_loader_param.v latency_buffer.v \
+        matched_filter_multi_segment.v matched_filter_processing_chain.v \
+        range_bin_decimator.v doppler_processor.v xfft_16.v fft_engine.v \
+        usb_data_interface.v usb_data_interface_ft2232h.v edge_detector.v radar_mode_controller.v \
         rx_gain_control.v cfar_ca.v mti_canceller.v fpga_self_test.v
 else
     echo "  (skipped receiver golden + system top + E2E — use without --quick)"
-    SKIP=$((SKIP + 4))
+    SKIP=$((SKIP + 6))
 fi
 
 echo ""