Files
FPGA-Neural/sim/int8_psram_integration_tb.v
T
micheleandClaude Sonnet 5 7e2711fa27 feat: widen ADDR_WIDTH to 23 bits for full 8MB PSRAM addressing
Bumps ADDR_WIDTH's default from 22 to 23 bits across every RTL
module (neuron_memory, layer_sequencer, spi_engine, spi_neuron_top,
mem_arbiter, int8_memory_access, memory_interface, psram_controller,
memory_model) and every testbench that mirrors it, so the system's
byte-address space reaches the full 8 MiB the recommended PSRAM part
(ISSI IS66WVE4M16EBLL-70BLI, docs/FPGA-Neural-Hardware-Design.md §3)
actually provides -- previously only 4 MiB (half the chip) was
reachable, since int8_memory_access.v's byte->word address shift
(addr >> 1) turned the old 22-bit byte address into only 21 real word
bits, one short of the chip's real 22-bit word address (A0-A21). At
23 bits, that same shift lands exactly on all 22 chip address lines,
so the whole part is usable now instead of deferred to a future
widening.

Also fixes a stray 22'd11-sized literal in layer_sequencer.v's
descriptor-table address increment (numerically already safe via
Verilog's zero-extension, but now correctly unsized so it always
matches ADDR_WIDTH instead of silently assuming 22).

Updated docs/FPGA-NeuralNetwork-Engine.md's SPI protocol address-field
note (23 bits, top 1 reserved bit instead of 2) and
docs/FPGA-Neural-Hardware-Design.md's PSRAM section (the "chip has
one spare address line" framing is gone now that all 22 are wired
and used).

Full regression (all 11 ADDR_WIDTH-touching testbenches, plus a
Yosys elaboration check of spi_neuron_top with the new default and
no override) passes clean.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WQV3vS9TXaGDJ5cRfnfidt
2026-09-02 21:00:46 +02:00

455 lines
12 KiB
Verilog

`timescale 1ns/1ps
module tb;
localparam ADDR_WIDTH = 23;
localparam DATA_WIDTH = 16;
localparam CLK_PERIOD = 12.5; // 80 MHz
// ============================================================
// Clock / Reset
// ============================================================
reg clk;
reg rst;
// ============================================================
// INT8 interface
// ============================================================
reg req;
reg wr;
reg [ADDR_WIDTH-1:0] addr;
reg signed [7:0] wdata;
wire signed [7:0] rdata;
wire ready;
// ============================================================
// memory_interface
// ============================================================
wire mem_req;
wire mem_wr;
wire [ADDR_WIDTH-1:0] mem_addr;
wire [DATA_WIDTH-1:0] mem_wdata;
wire mem_lb_n;
wire mem_ub_n;
wire [DATA_WIDTH-1:0] mem_rdata;
wire mem_ready;
// ============================================================
// Memory interface -> PSRAM controller
// ============================================================
wire psram_mem_req;
wire psram_mem_wr;
wire [ADDR_WIDTH-1:0] psram_mem_addr;
wire [DATA_WIDTH-1:0] psram_mem_wdata;
wire psram_mem_lb_n;
wire psram_mem_ub_n;
wire [DATA_WIDTH-1:0] psram_mem_rdata;
wire psram_mem_ready;
// ============================================================
// PSRAM physical interface
// ============================================================
wire [ADDR_WIDTH-1:0] psram_a;
wire [DATA_WIDTH-1:0] psram_dq;
wire psram_ce_n;
wire psram_oe_n;
wire psram_we_n;
wire psram_lb_n;
wire psram_ub_n;
wire psram_zz_n;
// ============================================================
// INT8 MEMORY ACCESS
// ============================================================
int8_memory_access #(
.ADDR_WIDTH(ADDR_WIDTH)
) int8_access (
.clk (clk),
.rst (rst),
.req (req),
.wr (wr),
.addr (addr),
.wdata (wdata),
.rdata (rdata),
.ready (ready),
.mem_req (mem_req),
.mem_wr (mem_wr),
.mem_addr (mem_addr),
.mem_wdata (mem_wdata),
.mem_lb_n (mem_lb_n),
.mem_ub_n (mem_ub_n),
.mem_rdata (mem_rdata),
.mem_ready (mem_ready)
);
// ============================================================
// MEMORY INTERFACE
// ============================================================
memory_interface #(
.ADDR_WIDTH(ADDR_WIDTH),
.DATA_WIDTH(DATA_WIDTH)
) memory_if (
.clk (clk),
.rst (rst),
.req (mem_req),
.wr (mem_wr),
.addr (mem_addr),
.wdata (mem_wdata),
.lb_n (mem_lb_n),
.ub_n (mem_ub_n),
.rdata (mem_rdata),
.ready (mem_ready),
.mem_req (psram_mem_req),
.mem_wr (psram_mem_wr),
.mem_addr (psram_mem_addr),
.mem_wdata (psram_mem_wdata),
.mem_lb_n (psram_mem_lb_n),
.mem_ub_n (psram_mem_ub_n),
.mem_rdata (psram_mem_rdata),
.mem_ready (psram_mem_ready)
);
// ============================================================
// PSRAM CONTROLLER
// ============================================================
psram_controller #(
.ADDR_WIDTH (ADDR_WIDTH),
.DATA_WIDTH (DATA_WIDTH),
.CLK_FREQ_MHZ (80)
) psram_ctrl (
.clk (clk),
.rst (rst),
.mem_req (psram_mem_req),
.mem_wr (psram_mem_wr),
.mem_addr (psram_mem_addr),
.mem_wdata (psram_mem_wdata),
.mem_lb_n (psram_mem_lb_n),
.mem_ub_n (psram_mem_ub_n),
.mem_rdata (psram_mem_rdata),
.mem_ready (psram_mem_ready),
.psram_a (psram_a),
.psram_dq (psram_dq),
.psram_ce_n(psram_ce_n),
.psram_oe_n(psram_oe_n),
.psram_we_n(psram_we_n),
.psram_lb_n(psram_lb_n),
.psram_ub_n(psram_ub_n),
.psram_zz_n(psram_zz_n)
);
// ============================================================
// PSRAM MODEL
// ============================================================
psram_model #(
.ADDR_WIDTH(ADDR_WIDTH),
.DATA_WIDTH(DATA_WIDTH),
.DEPTH(16384)
) psram (
.clk (clk),
.a (psram_a),
.dq (psram_dq),
.ce_n (psram_ce_n),
.oe_n (psram_oe_n),
.we_n (psram_we_n),
.lb_n (psram_lb_n),
.ub_n (psram_ub_n),
.zz_n (psram_zz_n)
);
// ============================================================
// Clock
// ============================================================
initial begin
clk = 1'b0;
forever #(CLK_PERIOD / 2.0)
clk = ~clk;
end
// ============================================================
// VCD
// ============================================================
initial begin
$dumpfile("sim/int8_psram_integration.vcd");
$dumpvars(0, tb);
end
// ============================================================
// Write INT8
// ============================================================
task write_byte;
input [ADDR_WIDTH-1:0] byte_addr;
input signed [7:0] data;
begin
@(posedge clk);
addr <= byte_addr;
wdata <= data;
wr <= 1'b1;
req <= 1'b1;
@(posedge clk);
req <= 1'b0;
wait (ready);
$display(
"WRITE BYTE addr=0x%08x data=0x%02x PASS",
byte_addr,
data
);
@(posedge clk);
end
endtask
// ============================================================
// Read INT8
// ============================================================
task read_byte;
input [ADDR_WIDTH-1:0] byte_addr;
input signed [7:0] expected;
begin
@(posedge clk);
addr <= byte_addr;
wr <= 1'b0;
req <= 1'b1;
@(posedge clk);
req <= 1'b0;
wait (ready);
if (rdata !== expected) begin
$display(
"READ BYTE addr=0x%08x FAIL got=0x%02x expected=0x%02x",
byte_addr,
rdata,
expected
);
$fatal;
end else begin
$display(
"READ BYTE addr=0x%08x data=0x%02x PASS",
byte_addr,
rdata
);
end
@(posedge clk);
end
endtask
// ============================================================
// Test
// ============================================================
integer i;
integer test_addr;
reg signed [7:0] test_data;
initial begin
req = 1'b0;
wr = 1'b0;
addr = 0;
wdata = 0;
rst = 1'b1;
repeat (5)
@(posedge clk);
rst = 1'b0;
$display("");
$display("========================================");
$display("INT8 + PSRAM FULL INTEGRATION TEST");
$display("========================================");
$display("");
// --------------------------------------------------------
// Wait for PSRAM initialization
// --------------------------------------------------------
wait (psram_ctrl.state == psram_ctrl.STATE_IDLE);
$display("PSRAM initialization complete");
$display("");
// ========================================================
// BASIC INT8 PACKING
// ========================================================
write_byte(22'h000000, 8'h12);
write_byte(22'h000001, 8'h34);
write_byte(22'h000002, 8'h56);
write_byte(22'h000003, 8'h78);
read_byte(22'h000000, 8'h12);
read_byte(22'h000001, 8'h34);
read_byte(22'h000002, 8'h56);
read_byte(22'h000003, 8'h78);
// ========================================================
// BYTE PRESERVATION
// ========================================================
write_byte(22'h000010, 8'h34);
write_byte(22'h000011, 8'h12);
write_byte(22'h000010, 8'hAA);
read_byte(22'h000010, 8'hAA);
read_byte(22'h000011, 8'h12);
write_byte(22'h000011, 8'hBB);
read_byte(22'h000010, 8'hAA);
read_byte(22'h000011, 8'hBB);
// ========================================================
// SIGNED INT8
// ========================================================
write_byte(22'h000020, -8'sd1);
write_byte(22'h000021, -8'sd128);
write_byte(22'h000022, 8'sd127);
read_byte(22'h000020, -8'sd1);
read_byte(22'h000021, -8'sd128);
read_byte(22'h000022, 8'sd127);
// ========================================================
// SPARSE ADDRESSES
// ========================================================
write_byte(22'h000100, 8'h11);
write_byte(22'h000101, 8'h22);
write_byte(22'h001000, 8'h33);
write_byte(22'h001001, 8'h44);
write_byte(22'h003FFE, 8'h55);
write_byte(22'h003FFF, 8'h66);
read_byte(22'h000100, 8'h11);
read_byte(22'h000101, 8'h22);
read_byte(22'h001000, 8'h33);
read_byte(22'h001001, 8'h44);
read_byte(22'h003FFE, 8'h55);
read_byte(22'h003FFF, 8'h66);
// ========================================================
// STRESS TEST
// ========================================================
$display("");
$display("========================================");
$display("INT8 PSRAM STRESS TEST");
$display("2048 WRITE + READ BYTE TRANSACTIONS");
$display("========================================");
$display("");
for (i = 0; i < 2048; i = i + 1) begin
test_addr =
((i * 7919) ^ (i << 5)) & 16'h7FFF;
test_data =
((i * 1237) ^ 8'hA5);
write_byte(
test_addr,
test_data
);
read_byte(
test_addr,
test_data
);
if ((i % 128) == 0)
$display(
"STRESS %0d / 2048 PASS",
i
);
end
// ========================================================
// Final result
// ========================================================
$display("");
$display("========================================");
$display("INT8 + PSRAM INTEGRATION TEST PASSED");
$display("BYTE ADDRESSING : PASS");
$display("LB# / UB# : PASS");
$display("INT8 PACKING : PASS");
$display("BYTE PRESERVATION : PASS");
$display("SIGNED INT8 : PASS");
$display("SPARSE ADDRESSES : PASS");
$display("2048 STRESS : PASS");
$display("========================================");
$display("");
$finish;
end
endmodule