FlintyLemming/PLFM_RADAR
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Fix P0/P1 RTL bugs found during pre-hardware audit

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P0-1: nco_400m_enhanced.v — DSP48E1 OPMODE corrected from PCIN to P
      feedback (was routing stale cascade data into accumulator)
P0-2: radar_receiver_final.v — removed same-clock CDC that corrupted
      ADC data path between ad9484_interface and DDC
P1-5: fir_lowpass.v — fixed zero replication count in coefficient
      symmetric extension ({0{1'b0}} is empty, now uses explicit 0)

Also updates .gitignore to exclude debug/scratch artifacts.

All 30+ testbenches pass (unit, co-sim, integration).
This commit is contained in:
Jason
2026-03-16 22:24:06 +02:00
parent f154edbd20
commit fd6094ee9e
4 changed files with 34 additions and 21 deletions
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9_Firmware/9_2_FPGA/radar_receiver_final.v
+9 -18
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@@ -103,9 +103,6 @@ wire clk_400m;
wire [7:0] adc_data_cmos; // 8-bit ADC data (CMOS, from ad9484_interface_400m)
wire adc_valid; // Data valid signal
wire [7:0] cdc_data_cmos; // 8-bit ADC data (CMOS)
wire cdc_valid; // Data valid signal
// ADC power-down control (directly tie low = ADC always on)
assign adc_pwdn = 1'b0;
@@ -121,18 +118,12 @@ ad9484_interface_400m adc (
.adc_dco_bufg(clk_400m)
);
cdc_adc_to_processing #(
.WIDTH(8),
.STAGES(3)
)cdc(
.src_clk(clk_400m),
.dst_clk(clk_400m),
.reset_n(reset_n),
.src_data(adc_data_cmos),
.src_valid(adc_valid),
.dst_data(cdc_data_cmos),
.dst_valid(cdc_valid)
);
// NOTE: The cdc_adc_to_processing instance that was here used src_clk=dst_clk=clk_400m
// (same clock domain — no crossing). Gray-code CDC on same-clock with fast-changing
// ADC data corrupts samples because Gray coding only guarantees safe transfer of
// values that change by 1 LSB at a time. The real 400MHz→100MHz CDC crossing is
// handled inside ddc_400m_enhanced via CIC decimation + CDC_FIR instances.
// Removed: cdc_adc_to_processing instance. ADC data now goes directly to DDC.
// 2. DDC Input Interface
wire signed [17:0] ddc_out_i;
@@ -145,9 +136,9 @@ ddc_400m_enhanced ddc(
.clk_400m(clk_400m), // 400MHz clock from ADC DCO
.clk_100m(clk), // 100MHz system clock //used by the 2 FIR
.reset_n(reset_n),
.adc_data(cdc_data_cmos), // ADC data at 400MHz (unsigned 0-255)
.adc_data_valid_i(cdc_valid), // Valid at 400MHz
.adc_data_valid_q(cdc_valid), // Valid at 400MHz
.adc_data(adc_data_cmos), // ADC data at 400MHz (direct from ADC interface)
.adc_data_valid_i(adc_valid), // Valid at 400MHz
.adc_data_valid_q(adc_valid), // Valid at 400MHz
.baseband_i(ddc_out_i), // I output at 100MHz
.baseband_q(ddc_out_q), // Q output at 100MHz
.baseband_valid_i(ddc_valid_i), // Valid at 100MHz