diff options
Diffstat (limited to 'cocotb_try/cic3_pdm.v')
| -rw-r--r-- | cocotb_try/cic3_pdm.v | 21 |
1 files changed, 9 insertions, 12 deletions
diff --git a/cocotb_try/cic3_pdm.v b/cocotb_try/cic3_pdm.v index 3d23d44..9e96742 100644 --- a/cocotb_try/cic3_pdm.v +++ b/cocotb_try/cic3_pdm.v @@ -102,21 +102,18 @@ module cic3_pdm ( // Bypass DC removal pcm_out <= scaled_out; end else begin - // Calculate the updated accumulator value first - reg signed [19:0] new_accumulator; + // Simple leaky integrator with sign extension case (dc_alpha) - 8'd1: new_accumulator = dc_accumulator - (dc_accumulator >>> 12) + {{4{scaled_out[15]}}, scaled_out}; - 8'd16: new_accumulator = dc_accumulator - (dc_accumulator >>> 8) + {{4{scaled_out[15]}}, scaled_out}; - 8'd64: new_accumulator = dc_accumulator - (dc_accumulator >>> 6) + {{4{scaled_out[15]}}, scaled_out}; - 8'd255: new_accumulator = dc_accumulator - (dc_accumulator >>> 4) + {{4{scaled_out[15]}}, scaled_out}; - default: new_accumulator = dc_accumulator - (dc_accumulator >>> 8) + {{4{scaled_out[15]}}, scaled_out}; + 8'd1: dc_accumulator <= dc_accumulator - (dc_accumulator >>> 12) + {{4{scaled_out[15]}}, scaled_out}; + 8'd16: dc_accumulator <= dc_accumulator - (dc_accumulator >>> 8) + {{4{scaled_out[15]}}, scaled_out}; + 8'd64: dc_accumulator <= dc_accumulator - (dc_accumulator >>> 6) + {{4{scaled_out[15]}}, scaled_out}; + 8'd128: dc_accumulator <= dc_accumulator - (dc_accumulator >>> 5) + {{4{scaled_out[15]}}, scaled_out}; + 8'd255: dc_accumulator <= dc_accumulator - (dc_accumulator >>> 4) + {{4{scaled_out[15]}}, scaled_out}; + default: dc_accumulator <= dc_accumulator - (dc_accumulator >>> 8) + {{4{scaled_out[15]}}, scaled_out}; endcase - // Update accumulator - dc_accumulator <= new_accumulator; - - // Output = input - NEW DC estimate (not old one) - pcm_out <= scaled_out - new_accumulator[19:4]; + // Output = input - DC estimate (using OLD estimate to avoid combinational loop) + pcm_out <= scaled_out - dc_accumulator[19:4]; end pcm_valid <= 1; end |