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chirp-v2 PR-F follow-up: doppler OOB read + dead cfar wires

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Two issues caught re-reviewing 7862f4d:

1. doppler_processor.v: at sub_frame = NUM_SUBFRAMES-1 (=2 in production),
   the read-ahead pointer was advanced one cycle past the last useful chirp,
   producing an out-of-range mem_read_addr (chirps 48/49 in a 48-chirp frame)
   on the BRAM read port. The result was never consumed — counter > CPS-1
   blocks the multiply — so the OOB read had no functional effect, but it
   still drives mem_mem[OOB_idx] every frame and would trigger Vivado synth
   range warnings. Gate the read_doppler_index advance on
   fft_sample_counter <= CHIRPS_PER_SUBFRAME - 3 so the last NBA at
   counter = CPS-3 schedules the data needed at counter = CPS-1 and no more.
   For sub_frame < NUM_SUBFRAMES-1 this just replaces previously-wasted
   forward reads with redundant reads of the same address; outputs are
   bit-exact.

2. radar_system_top.v: cfar_detect_class, cfar_detect_threshold_soft, and
   cfar_detect_count_cand were declared and connected to cfar_inst but went
   nowhere downstream. They will be wired to USB / telemetry in PR-G; until
   then they show up as dangling wires that Vivado optimises away with
   noisy warnings. Drop the wire decls and leave the cfar_ca output ports
   unconnected. The soft-tier comparison is still synthesized because the
   1-bit detect_flag (which IS wired) depends on noise_product_soft via the
   `else if (cur > thr_soft)` branch, so the candidate logic is preserved
   in the netlist — only the class / soft-thr / cand-count rails are gone.

Tests (parity with the PR-F numbers in 7862f4d):
  - tb_chirp_controller:   43/43 PASS
  - tb_chirp_contract:     10/10 PASS
  - tb_cfar_ca:            24/0  PASS
  - tb_mti_canceller:      43/43 PASS
  - tb_doppler_realdata:   2056/2056 PASS
  - tb_doppler_frame_start_gate: 21/21 PASS
  - tb_system_e2e:         33/49 PASS (PR-F baseline parity)
This commit is contained in:
Jason
2026-05-01 04:06:58 +05:45
parent 7862f4d63c
commit 51a94f0baf
2 changed files with 26 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
9_Firmware/9_2_FPGA/doppler_processor.v
View File

@@ -488,11 +488,22 @@ always @(posedge clk) begin
window_val_reg <= $signed(window_coeff[win_idx]);
end
// Advance BRAM read: chirp_base + (counter + 2).
// For NUM_SUBFRAMES * CHIRPS_PER_SUBFRAME = CHIRPS_PER_FRAME
// and counter <= CHIRPS_PER_SUBFRAME-1, chirp_base+offset
// is bounded by CHIRPS_PER_FRAME so no clamp is needed.
read_doppler_index <= current_sub_frame * CHIRPS_PER_SUBFRAME
+ {2'd0, fft_sample_counter[3:0]} + 6'd2;
// The last useful read is data[chirp_base + CPS-1], needed
// by mult_i_raw at counter=CPS-1. Working back through the
// 2-cycle BRAM-then-multiply pipeline, the last NBA that
// matters is at counter = CPS-3 (= 13 for CPS=16) which
// schedules read of base+CPS-1. After that, advancing
// would address chirp base+CPS or base+CPS+1 — past the
// end of the highest sub-frame's data window (e.g. chirps
// 48 / 49 with sub_frame=2 in a 48-chirp frame), which is
// outside MEM_DEPTH = RANGE_BINS * CHIRPS_PER_FRAME. The
// would-be values are never consumed, but the reads
// would still drive an out-of-range mem_read_addr. Stop
// the read pointer at the last useful chirp instead.
if (fft_sample_counter <= CHIRPS_PER_SUBFRAME - 3) begin
read_doppler_index <= current_sub_frame * CHIRPS_PER_SUBFRAME
+ {2'd0, fft_sample_counter[3:0]} + 6'd2;
end
end
if (fft_sample_counter == CHIRPS_PER_SUBFRAME + 1) begin

16
9_Firmware/9_2_FPGA/radar_system_top.v
View File

@@ -681,17 +681,21 @@ wire [`RP_RANGE_BIN_WIDTH_MAX-1:0] notched_range_bin = rx_range_bin;
// See cfar_ca.v for architecture details.
wire cfar_detect_flag;
wire [`RP_DETECT_CLASS_WIDTH-1:0] cfar_detect_class;
wire cfar_detect_valid;
wire [`RP_RANGE_BIN_WIDTH_MAX-1:0] cfar_detect_range;
wire [`RP_DOPPLER_BIN_WIDTH-1:0] cfar_detect_doppler;
wire [16:0] cfar_detect_magnitude;
wire [16:0] cfar_detect_threshold;
wire [16:0] cfar_detect_threshold_soft;
wire [15:0] cfar_detect_count;
wire [15:0] cfar_detect_count_cand;
wire cfar_busy_w;
wire [7:0] cfar_status_w;
// PR-F note: cfar_ca also drives detect_class[1:0], detect_threshold_soft,
// detect_count_cand. The soft-tier comparison still feeds detect_flag (which
// is wired to USB), so the candidate logic is preserved in synth — but the
// class / soft-thr / cand-count outputs themselves don't go anywhere until
// PR-G adds the USB opcodes (0x28 alpha_soft + bulk-frame v2). We deliberately
// leave the cfar_ca output ports unconnected here so they do NOT show up as
// dangling wires in radar_system_top; PR-G will reattach them.
cfar_ca cfar_inst (
.clk(clk_100m_buf),
@@ -715,17 +719,17 @@ cfar_ca cfar_inst (
// Detection outputs
.detect_flag(cfar_detect_flag),
.detect_class(cfar_detect_class),
.detect_class(), // PR-F: routed in PR-G (USB 0x2A read)
.detect_valid(cfar_detect_valid),
.detect_range(cfar_detect_range),
.detect_doppler(cfar_detect_doppler),
.detect_magnitude(cfar_detect_magnitude),
.detect_threshold(cfar_detect_threshold),
.detect_threshold_soft(cfar_detect_threshold_soft),
.detect_threshold_soft(), // PR-F: routed in PR-G
// Status
.detect_count(cfar_detect_count),
.detect_count_cand(cfar_detect_count_cand),
.detect_count_cand(), // PR-F: routed in PR-G (telemetry)
.cfar_busy(cfar_busy_w),
.cfar_status(cfar_status_w)
);