`radar_receiver_final.v:246` had `assign adc_pwdn = 1'b0;` -- the AD9484
PWDN pin was hard-tied LOW with no path for the host or MCU to assert
it. Combined with AUDIT-C13 (CSB hard-tied HIGH on the production board,
no SPI access to the AD9484), the ADC was fully un-recoverable from a
stuck state without dropping main power -- which also drops the
VBAT-backed BKPSRAM persistence (MCU-A4 OCXO warmup, MCU-A7 emergency
flag) and forces a 180 s warmup soak.
Opcode 0x32 was reserved during the AUDIT-C3 fix (commit 24ef5e7) for
exactly this purpose. Wire it through:
- `radar_system_top.v` adds `reg host_adc_pwdn` next to `host_adc_format`,
resets to 1'b0 (matches historical hard-tied state -- preserves
bringup behavior), latches `usb_cmd_value[0]` on opcode 0x32, drives
the new receiver input port.
- `radar_receiver_final.v` adds `input wire host_adc_pwdn`, replaces the
hard-coded `assign adc_pwdn = 1'b0` with `assign adc_pwdn = host_adc_pwdn`.
- No CDC: `host_adc_pwdn` is a stable single-bit level driven from the
clk_100m register straight to the I/O pad. AD9484 PWDN is asynchronous
w.r.t. the ADC clock; the chip re-acquires its DLL on PWDN deassert.
XDC pin assignments were already in place from AUDIT-C15 (50T:T5,
200T:P20, both LVCMOS25 driving the AD9484 PWDN net via the R36/R37
divider on the Main Board).
Verification:
- new tb/tb_adc_pwdn_opcode.v, 15/15 PASS:
T1 reset -> host_adc_pwdn=0, adc_pwdn pin=0 (ADC powered up)
T2 opcode 0x32 val=1 -> host_adc_pwdn=1, pin=1 (PWDN asserted)
T3 opcode 0x32 val=0 -> cleared
T4 only bit[0] consumed (upper bits ignored)
T5 unrelated opcodes (0x33, 0x01) don't disturb host_adc_pwdn
T6 cmd_valid_100m gating works
- Quick regression 33/33 PASS (was 32/32; +1 new test, 0 regressions)
- Lint: 0 errors
Pre-fix S_IDLE had two independent if-branches: one for frame_start_pulse
(resets pointers) and one for data_valid (transitions to S_ACCUMULATE).
A data_valid arriving before frame_start_pulse would advance the FSM with
whatever pointers happened to be live, and the BRAM write block would write
the sample into mem_write_addr = (write_chirp_index*RANGE_BINS) + 0.
In current operation the race is benign — end-of-S_ACCUMULATE always zeros
write_chirp_index/write_range_bin (line 287-288) and the MF pipeline latency
(~165 µs) is millions of cycles longer than the frame_start CDC latency
(~50 ns), so frame_start always arrives first. But the FSM relies on an
undocumented system-level invariant; a future code path that leaves
pointers stale on entry to S_IDLE would silently corrupt the first sample.
Fix: add a `frame_armed` register set when frame_start_pulse arrives in
S_IDLE, cleared on transition to S_ACCUMULATE. Both the FSM transition and
the BRAM write block gate on `(frame_start_pulse || frame_armed)`. The OR
admits the same-cycle case where both arrive together (write to addr 0
still resolves correctly because both blocks use the same gate).
Verification: tb_doppler_frame_start_gate 21/21 PASS, quick regression
32/32 PASS (was 31/31; +1 new test, 0 regressions). tb_doppler_realdata
(full FFT pipeline) still passes — gate transparent to normal operation.
AUDIT-C12: usb_data_interface_ft2232h had a misleading single-buffer comment
that overstated the timing slack and referenced a frame_ack_toggle CDC that
was never implemented. Re-verified actual numbers: at 178 fps the slack is
1.14 ms (20%), not "much shorter than gap". No data corruption today (write
order matches read order, addresses don't collide), but frame_complete
firing while WR_FSM is still draining the previous frame causes silent
frame drops via the missed frame_ready_toggle edge.
Fix is instrumentation, not architectural rework: add wr_done_toggle
(ft_clk -> clk CDC) on WR_DONE -> WR_IDLE, track frame_pending in clk
domain, count drops in 7-bit saturating frame_drop_count, surface in
unused upper 7 bits of status_words[5]. Host now has visibility into the
failure mode if margin ever shrinks (faster frame rate or USB bandwidth
shortfall). Replaced misleading comment with corrected timing breakdown.
AUDIT-S22: cfar_ca emits one detection per 3 cycles (THR/MUL/CMP); the
detection RMW takes 3 cycles. Match by construction today, fragile against
any CFAR speedup. Added a header comment in cfar_ca.v documenting the
dependency, and a SIMULATION-only assertion in usb_data_interface_ft2232h.v
that fires [ASSERT FAIL] AUDIT-S22 if cfar_valid arrives while RMW busy.
Catches silent-drop regressions in the test suite.
Verification: new tb_ft2232h_frame_drop.v with 5 scenarios (no drops /
stalled drops / multi-drop / recovery / saturation at 127) - 10/10 PASS.
Quick regression 31/31 PASS (was 30/30; +1 new test, 0 regressions).
tb_radar_receiver_final had three pre-existing issues that all surfaced as
fails in regression (32 passed, 2 failed before; 34 passed, 0 after):
1. host_range_mode was undriven (floating 2'bzz); rmc log confirmed
"Auto-scan starting, range_mode=z". Add explicit 2'b01 (long-range
dual-chirp) for the test scenario.
2. DDC_MAX_ENERGY threshold (2^56) was sized for an unspecified earlier
stimulus; the test feeds a deliberately-loud 120 MHz sawtooth that
produces ~1.27e17 energy over 2M samples. Raised to 2^60 (~10x
observed) so B1b catches true overflow without false-firing.
3. The 9 doppler-frame-dependent checks (S4-S9, G1, B2a, B3, B4) need
~108 ms simulated time to fill a 32-chirp Doppler frame because the
in-house fft_engine takes ~340 K cycles per multi-segment chirp
(RX-NEW-3, commit 5c8cc8c). Iverilog can't elaborate the Xilinx FFT IP
that would make this tractable. Guard those checks behind
`ifdef FFT_USE_XILINX_IP` so iverilog cleanly SKIPs them with an
explanatory line; XSim with the IP runs them normally.
Also tightens run_regression.sh's pass/fail regex from
^\[(PASS|FAIL)([^]]*)\] to ^\[(PASS|FAIL)( [0-9]+)?\] so informational
tags like [FAIL-INFO] (used to document the known RX-NEW-1 fft_engine
bin-shift in tb_matched_filter_processing_chain.v) no longer false-fire
as real failures. The Matched Filter Chain test goes from FAIL (40 pass,
2 false-fails) to PASS (40 checks).
Regression: 34 passed, 0 failed.
latency_buffer.v has had zero non-tb instantiations since RX-B (2026-04-23)
replaced its hookup in radar_receiver_final with a 1-FF alignment register.
The module was being kept "for potential future use" — exactly the kind of
dead weight the codebase does not need. Deleted, along with all build /
test infrastructure that dragged it along:
- 9_Firmware/9_2_FPGA/latency_buffer.v
- 9_Firmware/9_2_FPGA/tb/tb_latency_buffer.v
- run_regression.sh: removed from RTL_FILES and RECEIVER_RTL
- scripts/200t/build_200t.tcl: removed from synthesis source list
- tb/tb_system_e2e.v: removed from header compile-string example
- tb/cosim/validate_mem_files.py: deleted test_latency_buffer() (~75 lines),
its call site, and the corresponding entry in the module docstring
Historical RX-B comments referencing latency_buffer in radar_receiver_final.v,
tb_rxb_fullchain_latency.v, and tb_rxb_latency_measure.v are kept — they
explain WHY the module was removed, which is still useful design archaeology.
Two doc-only housekeeping touches bundled in:
- plfm_chirp_controller.v: replaced two empty "CRITICAL FIX: Generate
valid signal" labels at LONG_CHIRP and SHORT_CHIRP with one shared
chirp_valid policy comment block above LONG_CHIRP that explains the
actual rationale (downstream FIFO underrun on trailing samples).
- v7/models.py: replaced the "range_resolution and velocity_resolution
should be calibrated" docstring (sounded like an open TODO but was a
documented placeholder) with a clear pointer to the GUI-C3 fix in
workers.py:RadarDataWorker so future readers know the live path
derives correct values from WaveformConfig.
FPGA quick regression unchanged: 28/29 (1 fail is the unrelated iverilog/
Xilinx-IP RX-NEW-3 gap). GUI suite 180/180. Ruff clean.
Replaces the in-house iterative fft_engine.v in the matched-filter chain
with the Pipelined Streaming Xilinx FFT IP, closing RX-NEW-3 (FFT chain
~11x too slow vs PRI budget).
Components:
* ip/xfft_2048_ip/xfft_2048_ip.xci — committed IP definition
(16-bit fixed point, BFP scaling, convergent rounding, natural order,
pipelined-streaming, BRAM data/reorder/phase factors). Vivado
regenerates .dcp / sim-netlist from this on each build.
* scripts/50t/gen_xfft_2048_ip.tcl — IP-Catalog generation script
* scripts/50t/run_xfft_xsim.sh — XSim batch runner for tb_xfft_2048_xsim
* xfft_2048.v — AXI-Stream wrapper. FFT_USE_XILINX_IP define routes to
real LogiCORE for synth/XSim; falls back to fft_engine batched
one-shot for iverilog (unit coverage only).
* fft_engine_axi_bridge.v — exposes legacy fft_engine port surface on
top of the xfft_2048 AXI wrapper, so the chain swap is a 1-line
module-name change.
* matched_filter_processing_chain.v — fft_engine -> fft_engine_axi_bridge
* scripts/50t/build_50t.tcl — read_ip + generate_target + synth_ip;
adds FFT_USE_XILINX_IP to verilog defines.
* tb/tb_xfft_2048_xsim.v — XSim verification (DC, impulse, tone bin 128).
All 5 assertions PASS on remote with the real IP; tuser=0x0a (BLK_EXP=10)
confirms BFP scaling working.
Local iverilog regression: 32/34 PASS — identical to baseline. Same two
RX-NEW-3 failures (Receiver Integration, Matched Filter Chain) — these
only resolve in remote XSim with the real IP, since iverilog uses the
fft_engine fallback inside xfft_2048 (~150K cycles/pass, not the
~2200-cycle Pipelined Streaming throughput). MF cosim 4/4 PASS confirms
bridge bit-exact in fallback mode.
Pending: remote XSim of tb_radar_receiver_final to demonstrate Doppler
frames produced within PRI budget; remote synth to confirm DSP/timing
post-IP.
- run_regression.sh: add frequency_matched_filter.v to PROD_RTL and RECEIVER_RTL
compile groups (was implicitly required after inline behavioural FFT in
matched_filter_processing_chain.v was removed); empty EXTRA_RTL with set -u
guards; bump Matched Filter Chain timeout to 600s.
- run_regression.sh: add two PHASE 3 tests — tb_rxb_latency_measure (chain
pipeline depth) and tb_rxb_fullchain_latency (multi-segment + chain).
- radar_receiver_final.v: replace dangling delayed_ref_i/q references (left
over from latency_buffer removal) with ref_chirp_real/imag.
- tb/tb_radar_receiver_final.v: chain-state debug uses production
collect_count/out_count signals instead of the deleted SIMULATION-only
fwd_in_count.
- tb/tb_rxb_latency_measure.v: add explicit [PASS]/[FAIL] markers around the
2007..2107 cycle expected-latency window.
Hand-merged files modified on both fix/pre-bringup-audit-p0 and
feat/fft-2048-upgrade. Wave 1 (commit 60e49c7) took 20 files from fft
verbatim; this wave resolves the overlap.
- run_regression.sh: 3-way merge. Adopts fft's ${RECEIVER_RTL[@]} array
refactor and drops the self-blessing golden pair from p0. Skip count
bumped to 5.
- usb_data_interface.v (FT601/200T): p0 FSM + clock-loss watchdog kept
wholesale; widened stream_control 3 -> 6 bits to carry fft's extended
mode bits through the CDC sync chain and the 0xFF status word.
- mti_canceller.v: fft's BRAM-inferred 512-range-bin implementation as
the base, with p0's F-6.3 saturation counter grafted onto the d1
pipeline stage. Overflow detection uses the top-two-bits disagreement
on diff_{i,q}_full (DATA_WIDTH+1 signed).
- radar_receiver_final.v: fft's 2048-pt / 512-bin structure + p0
diagnostic plumbing (ADC overrange sticky+CDC, DDC diagnostics,
tx_frame_start edge detector replacing chirp_counter frame sync,
mti_saturation_count, range_decim_watchdog).
- radar_system_top.v: clean 3-way merge, orthogonal regions
(+38 / -27).
- usb_data_interface_ft2232h.v (FT2232H/50T): fft's per-frame bulk BRAM
rewrite kept wholesale. Ported two p0 items that are orthogonal to
the write FSM:
* ft_clk-loss watchdog (heartbeat + 2FF ASYNC_REG sync + 16-bit
timeout) ORed into a 2FF sync'd ft_effective_reset_n for the FSM.
* rd_cmd_complete flag so RD_DEASSERT can distinguish a legitimate
3-byte completion from an ft_rxf_n abort that also zeros
rd_byte_cnt.
Deliberately NOT taken from 2401f5f: cic_decimator_4x_enhanced.v and
ddc_400m.v reset-strategy changes. Those conflict with p0's shipped
registered-sync-reset + max_fanout=25 distribution, which is already
timing-clean on the production build.
Regenerate all real-data golden reference hex files against the current
dual 16-point FFT Doppler architecture (staggered-PRI sub-frames).
The old hex files were generated against the previous 32-point single-FFT
architecture and caused 2048/2048 mismatches in both strict real-data TBs.
Changes:
- Regenerate doppler_ref_i/q.hex, fullchain_doppler_ref_i/q.hex, and all
downstream golden files (MTI, DC notch, CFAR) via golden_reference.py
- Add tb_doppler_realdata (exact-match, ADI CN0566 data) to regression
- Add tb_fullchain_realdata (exact-match, decim->Doppler chain) to regression
- Both TBs now pass: 2048/2048 bins exact match, MAX_ERROR=0
- Update CI comment: 23 -> 25 testbenches
- Fill in STALE_NOTICE.md with regeneration instructions
Regression: 25/25 pass, 0 fail, 0 skip. ruff check: 0 errors.
- Remove xfft_32.v, tb_xfft_32.v, and fft_twiddle_32.mem (dead code
since PR #33 moved Doppler to dual 16-pt FFT architecture)
- Update run_regression.sh: xfft_16 in PROD_RTL, remove xfft_32 from
EXTRA_RTL and all compile commands
- Update tb_fft_engine.v to test with N=16 / fft_twiddle_16.mem
- Update validate_mem_files.py: validate fft_twiddle_16.mem instead of 32
- Update testbenches and golden data from main_cleanup branch to match
dual-16 architecture (tb_doppler_cosim, tb_doppler_realdata,
tb_fullchain_realdata, tb_fullchain_mti_cfar_realdata, tb_system_e2e,
radar_receiver_final, golden_doppler.mem)
- Update CONTRIBUTING.md with full regression test instructions covering
FPGA, MCU, GUI, co-simulation, and formal verification
Regression: 23/23 FPGA, 20/20 MCU, 57/58 GUI, 56/56 mem validation,
all co-sim scenarios PASS.
- usb_data_interface.v: Add 3 self-test status inputs, expand status packet
from 7 words (header + 5 data + footer) to 8 words (header + 6 data + footer).
New status_words[5] carries {busy, detail[7:0], flags[4:0]}.
- radar_system_top.v: Wire self_test_flags_latched, self_test_detail_latched,
self_test_busy to usb_data_interface ports. Add opcode 0x31 as status
readback alias so host can read self-test results.
- tb_usb_data_interface.v: Add self-test port connections, verify word 5 in
Group 16, add Group 18 (busy flag + partial failure variant). 81 checks pass.
- run_regression.sh: Add fpga_self_test.v to PROD_RTL lint list and system-
level compile lists. Add tb_fpga_self_test as Phase 1 unit test.
- 24/24 regression tests pass, lint clean (0 errors, 4 advisory warnings).
MTI canceller (2-pulse, H(z)=1-z^{-1}) between range decimator and
Doppler processor. Subtracts previous chirp from current, nulling DC
Doppler (stationary clutter). Pass-through when host_mti_enable=0.
DC notch filter (post-Doppler, pre-CFAR) zeros bins within
+/-host_dc_notch_width of DC. Complements MTI for residual clutter.
New host registers: 0x26 (mti_enable), 0x27 (dc_notch_width).
Both default to 0 (disabled) - fully backward-compatible.
Verification: 23/23 regression, 29/29 MTI standalone, 3/3 real-data
co-sim (5137/5137 exact match) all PASS.
RTL fixes discovered via new end-to-end testbench:
- plfm_chirp_controller: TX/RX mixer enables now mutually exclusive
by FSM state (Fix#4), preventing simultaneous TX+RX activation
- usb_data_interface: stream control reset default 3'b001 (range-only),
added doppler/cfar data_pending sticky flags, write FSM triggers on
range_valid only — eliminates startup deadlock (Fix#5)
- radar_receiver_final: STM32 toggle signals wired through for mode-00
pass-through, dynamic frame detection via host_chirps_per_elev
- radar_system_top: STM32 toggle signal wiring to receiver instance
- chirp_memory_loader_param: explicit readmemh range for short chirp
Test infrastructure:
- New tb_system_e2e.v: 46 checks across 12 groups (reset, TX, safety,
RX, USB R/W, CDC, beam scanning, reset recovery, stream control,
latency budgets, watchdog)
- tb_usb_data_interface: Tests 21/22/56 updated for data_pending
architecture (preload flags, verify consumption instead of state)
- tb_chirp_controller: mixer tests T7.1/T7.2 updated for Fix#4
- run_regression.sh: PASS/FAIL regex fixed to match only [PASS]/[FAIL]
markers, added E2E test entry
- Updated rx_final_doppler_out.csv golden data
Adds two-layer lint pass (iverilog -Wall + custom static checks) that
catches part-select OOB errors and case-without-default warnings before
pushing to remote Vivado. Catches the exact Synth 8-524 class error that
broke Build 18 initial attempt. Lint errors abort regression; warnings
are advisory. Regenerated golden data for BRAM-migrated matched filter.
Jason