Files
FPGA-Neural/synth/ecp5/top.v
T
michele cfd5e98a0e feat: add FPGA-Neural benchmark tooling + same-tier ECP5 P2/P4/P8 results
tools/fpga_benchmark.py: parametric Yosys + nextpnr-ecp5 benchmark
harness for the LFE5U-45F-8BG381 (speed grade -8, 80 MHz target),
sweeping PARALLEL over the neuron layer and parsing Fmax/LUT4/DFF/DSP
utilization out of the nextpnr report into JSON/CSV.

synth/ecp5/p2, p4, p8: real synthesis+PnR results backing the
same-price-tier FPGA comparison (P2: 87.88 MHz PASS, P4: 75.01 MHz
FAIL, P8: 147.62 MHz PASS -- non-monotonic, dominated by placement
noise since the whole design uses <2% of the device's LUT4 fabric at
every setting, and P8 notably maps to 0 DSP blocks vs 8/16 for P2/P4).

synth/ecp5/top.v: benchmark harness top-level, reworked to generate
deterministic non-constant X/weights/bias via `keep`-attributed
generate blocks so Yosys can't constant-fold the datapath away.

Also adds .gitignore for Python's __pycache__/*.pyc.
2026-09-02 19:48:03 +02:00

120 lines
2.5 KiB
Verilog

module top #(
parameter DATA_WIDTH = 8,
parameter N_INPUTS = 256,
parameter N_NEURONS = 4,
parameter PARALLEL = 8,
parameter ACC_WIDTH = 32
)(
input wire clk,
input wire rst,
input wire start,
output wire signed [DATA_WIDTH*N_NEURONS-1:0] y_bus,
output wire busy,
output wire done
);
localparam X_BITS = DATA_WIDTH * N_INPUTS;
localparam W_BITS = DATA_WIDTH * N_INPUTS * N_NEURONS;
localparam B_BITS = DATA_WIDTH * N_NEURONS;
/*
* Deterministic benchmark vectors.
*
* These are INTERNAL signals.
* They are deliberately marked keep so that Yosys does not
* constant-fold the complete neural datapath away.
*/
(* keep = "true" *)
wire signed [X_BITS-1:0] x_bus;
(* keep = "true" *)
wire signed [W_BITS-1:0] weights_bus;
(* keep = "true" *)
wire signed [B_BITS-1:0] bias_bus;
/*
* Generate deterministic non-zero INT8 data.
*
* Each byte is a different constant. The buses remain internal,
* so nextpnr sees only the 37 real top-level I/Os.
*/
genvar i;
genvar n;
generate
for (i = 0; i < N_INPUTS; i = i + 1) begin : GEN_X
localparam integer XV =
((i * 17 + 3) % 31) - 15;
assign x_bus[
i*DATA_WIDTH +: DATA_WIDTH
] = XV;
end
for (n = 0; n < N_NEURONS; n = n + 1) begin : GEN_WN
for (i = 0; i < N_INPUTS; i = i + 1) begin : GEN_WI
localparam integer WV =
((n * 29 + i * 13 + 5) % 31) - 15;
assign weights_bus[
(n*N_INPUTS+i)*DATA_WIDTH
+: DATA_WIDTH
] = WV;
end
end
for (n = 0; n < N_NEURONS; n = n + 1) begin : GEN_B
localparam integer BV =
((n * 7 + 1) % 9) - 4;
assign bias_bus[
n*DATA_WIDTH
+: DATA_WIDTH
] = BV;
end
endgenerate
/*
* Real neural-network layer.
*/
(* keep_hierarchy = "true" *)
layer #(
.DATA_WIDTH(DATA_WIDTH),
.N_INPUTS(N_INPUTS),
.N_NEURONS(N_NEURONS),
.PARALLEL(PARALLEL),
.ACC_WIDTH(ACC_WIDTH)
) dut (
.clk(clk),
.rst(rst),
.start(start),
.x_bus(x_bus),
.weights_bus(weights_bus),
.bias_bus(bias_bus),
.y_bus(y_bus),
.busy(busy),
.done(done)
);
endmodule