fix: incorrect fifo threshold value

Reviewed-on: #6

rtl/accum/src/out_axis_fifo.sv

@@ -0,0 +1,193 @@
+module out_axis_fifo #(
+    parameter ACCUM_WIDTH = 32,
+    parameter WINDOW_SIZE = 65,
+    parameter PACKET_SIZE = 1024
+) (
+    input  logic                eth_clk_in,
+    input  logic                acc_clk_in,
+    input  logic                rst,
+    input  logic [31:0]         smp_num,
+
+    // AXI stream master for output, eth_clk_in domain
+    output logic [7:0]          s_axis_tdata,
+    output logic                s_axis_tvalid,
+    input  logic                s_axis_tready,
+    output logic                s_axis_tlast,
+
+    // data from acc
+    input  logic [ACCUM_WIDTH-1:0]   acc_din,
+    input  logic                     din_valid,
+    
+    // input pulse
+    input  logic                readout_begin,
+
+    // output pulses
+    output logic batch_req,
+    output logic finish      
+);
+
+    // fifo params calc
+    // round up to be enough for 2xPACKET_SIZE storage
+    localparam int MIN_BYTES      = 2 * PACKET_SIZE;
+    localparam int MIN_BITS       = MIN_BYTES * 8;
+    localparam int MIN_WR_WORDS   = (MIN_BITS + ACCUM_WIDTH - 1) / ACCUM_WIDTH; // ceil div
+    localparam int WDEPTH_BITS    = $clog2(MIN_WR_WORDS);
+    localparam int FIFO_WDEPTH    = 1 << WDEPTH_BITS;
+
+    localparam int FIFO_RDEPTH     = FIFO_WDEPTH * ACCUM_WIDTH / 8;
+    localparam int RDEPTH_BITS     = $clog2(FIFO_RDEPTH) + 1;
+
+
+    wire rd_unavail;
+    wire wr_unavail;
+    reg rd_en;
+    
+    
+    typedef enum logic [2:0] {
+        WR_IDLE         = 3'd0,
+        WR_CHECK        = 3'd1,
+        WR_RUN          = 3'd2,
+        WR_END          = 3'd3
+    } wr_state_t;
+
+    (* MARK_DEBUG="true" *) wr_state_t wr_state;
+    
+    // Write FSM
+    reg [31:0] wr_cnt;       // current BIT mem ptr
+    reg [31:0] wr_batch_tgt; // next 'target' that should be written from batch
+    reg [31:0] wr_total;     // total BITS to be sent!
+
+    // NOTE:
+    // each written "acc_din" ACCUM_WIDTH word
+    // is counted as WINDOWS_SIZE samples actually
+    // because hw division for counters is painful
+    // so we just increased the counter sizes
+
+    always_ff @(posedge acc_clk_in or posedge rst) begin
+        if (rst) begin
+            wr_state        <= WR_IDLE;
+            wr_cnt          <= 32'b0;
+            wr_batch_tgt    <= 32'b0;
+            wr_total        <= 32'b0;
+            batch_req       <= 0;
+            finish          <= 0;
+            
+        end else begin
+
+            case (wr_state)
+                // wait until readout is requested
+                WR_IDLE: begin
+                    if (readout_begin) begin 
+                        wr_cnt <= 32'b0;
+                        wr_state <= WR_CHECK;
+                        wr_total <= smp_num * ACCUM_WIDTH;
+                        wr_batch_tgt <= 32'b0;
+                    end
+                end
+                
+                // wait until we can request a word
+                // depends on prog_full signal
+                WR_CHECK: begin
+                    if (~wr_unavail) begin
+                        batch_req <= 1;
+                        // should give us exactly PACKET_SIZE * 8 bits
+                        // multiplied by WINDOW_SIZE, because we count 
+                        // each given ACCUM_WIDTH word as WINDOWS_SIZE samples !!!
+                        wr_batch_tgt <= wr_batch_tgt + (8 * WINDOW_SIZE * PACKET_SIZE);
+                        wr_state <= WR_RUN;
+                    end else begin
+                        batch_req <= 0;
+                    end
+                end
+
+                // wait until all requested packet is written
+                WR_RUN: begin
+                    batch_req <= 0;
+                    if (din_valid) begin
+                        // data supplied
+                        // count as we got WINDOW_SIZE samples
+                        wr_cnt <= wr_cnt + ACCUM_WIDTH * WINDOW_SIZE;
+                    end else if (wr_cnt == wr_batch_tgt) begin
+                        // got enough words
+                        wr_state <= WR_END;
+                    end else if (wr_cnt > wr_batch_tgt) begin
+                        // weird case when accum gave us too much words
+                        // block resets
+                        wr_cnt <= 32'hffffffff;  // sort of signal for sim/ila
+                        wr_state <= WR_END;
+                    end
+                end
+
+                // check if this was last data batch
+                WR_END: begin
+                    // here we check that we sent enough data
+                    // wr_cnt should be by design PACKET_SIZE-aligned
+                    if (wr_cnt >= wr_total) begin
+                        finish <= 1;
+                        wr_state <= WR_IDLE;
+                    end else begin
+                        // next word
+                        wr_state <= WR_CHECK;
+                    end
+                end
+            endcase
+        end
+    end
+    
+   // xpm_fifo_async: Asynchronous FIFO
+   // Xilinx Parameterized Macro, version 2025.1
+
+   xpm_fifo_async #(
+      .DOUT_RESET_VALUE("0"),        // String
+      .FIFO_READ_LATENCY(1),         // DECIMAL
+      .FIFO_WRITE_DEPTH(FIFO_WDEPTH), 
+      .FULL_RESET_VALUE(0),
+      .PROG_EMPTY_THRESH(PACKET_SIZE),
+      .PROG_FULL_THRESH(PACKET_SIZE / (ACCUM_WIDTH / 8)),
+      .RD_DATA_COUNT_WIDTH(RDEPTH_BITS),    
+      .READ_DATA_WIDTH(8),           // always 8 bit for eth
+      .READ_MODE("fwft"),            
+      .SIM_ASSERT_CHK(1),            // DECIMAL; 0=disable simulation messages, 1=enable simulation messages
+      .USE_ADV_FEATURES("1606"),     // String
+      .WRITE_DATA_WIDTH(ACCUM_WIDTH),
+      .WR_DATA_COUNT_WIDTH(WDEPTH_BITS)
+   )
+   xpm_fifo_async_inst (
+
+      .data_valid(s_axis_tvalid),       // 1-bit output: Read Data Valid: When asserted, this signal indicates that valid data is available on the
+                                     // output bus (dout).
+
+      .dout(s_axis_tdata),
+      .empty( ), 
+ 
+      .full( ),                 
+
+      .prog_empty(rd_unavail),       // 1-bit output: Programmable Empty: This signal is asserted when the number of words in the FIFO is less than
+                                     // or equal to the programmable empty threshold value. It is de-asserted when the number of words in the FIFO
+                                     // exceeds the programmable empty threshold value.
+
+      .prog_full(wr_unavail),         // 1-bit output: Programmable Full: This signal is asserted when the number of words in the FIFO is greater than
+                                     // or equal to the programmable full threshold value. It is de-asserted when the number of words in the FIFO is
+                                     // less than the programmable full threshold value.
+
+      .rd_data_count( ), // RD_DATA_COUNT_WIDTH-bit output: Read Data Count: This bus indicates the number of words read from the FIFO.
+
+      .wr_data_count( ), // WR_DATA_COUNT_WIDTH-bit output: Write Data Count: This bus indicates the number of words written into the
+                                     // FIFO.
+
+
+
+
+      .rd_clk(eth_clk_in),               // 1-bit input: Read clock: Used for read operation. rd_clk must be a free running clock.
+      .rd_en(rd_en),                 // 1-bit input: Read Enable: If the FIFO is not empty, asserting this signal causes data (on dout) to be read
+                                     // from the FIFO. Must be held active-low when rd_rst_busy is active high.
+
+      .rst(rst),
+      
+      .din(acc_din),                     // WRITE_DATA_WIDTH-bit input: Write Data: The input data bus used when writing the FIFO.
+      .wr_clk(acc_clk_in),               // 1-bit input: Write clock: Used for write operation. wr_clk must be a free running clock.
+      .wr_en(din_valid) 
+
+   );
+
+endmodule

rtl/accum/tests/Makefile

@@ -0,0 +1,52 @@
+# SPDX-License-Identifier: MIT
+#
+# Copyright (c) 2025 FPGA Ninja, LLC
+#
+# Authors:
+# - Alex Forencich
+#
+
+# FPGA settings
+FPGA_PART = xc7a35tfgg484-1
+FPGA_TOP = control
+FPGA_ARCH = artix7
+
+RTL_DIR = ../src
+
+
+include ../../../scripts/vivado.mk
+
+SYN_FILES += $(sort $(shell find ../src -type f \( -name '*.v' -o -name '*.sv' \)))
+
+XCI_FILES = $(sort $(shell find ../src -type f -name '*.xci'))
+
+XDC_FILES += ../../../constraints/ax7a035b.xdc
+# XDC_FILES += test_timing.xdc
+
+# SYN_FILES += controller_tb.sv
+# SIM_TOP = control_tb
+
+
+program: $(PROJECT).bit
+	echo "open_hw_manager" > program.tcl
+	echo "connect_hw_server" >> program.tcl
+	echo "open_hw_target" >> program.tcl
+	echo "current_hw_device [lindex [get_hw_devices] 0]" >> program.tcl
+	echo "refresh_hw_device -update_hw_probes false [current_hw_device]" >> program.tcl
+	echo "set_property PROGRAM.FILE {$(PROJECT).bit} [current_hw_device]" >> program.tcl
+	echo "program_hw_devices [current_hw_device]" >> program.tcl
+	echo "exit" >> program.tcl
+	vivado -nojournal -nolog -mode batch -source program.tcl
+
+$(PROJECT).mcs $(PROJECT).prm: $(PROJECT).bit
+	echo "write_cfgmem -force -format mcs -size 16 -interface SPIx4 -loadbit {up 0x0000000 $*.bit} -checksum -file $*.mcs" > generate_mcs.tcl
+	echo "exit" >> generate_mcs.tcl
+	vivado -nojournal -nolog -mode batch -source generate_mcs.tcl
+	mkdir -p rev
+	COUNT=100; \
+	while [ -e rev/$*_rev$$COUNT.bit ]; \
+	do COUNT=$$((COUNT+1)); done; \
+	COUNT=$$((COUNT-1)); \
+	for x in .mcs .prm; \
+	do cp $*$$x rev/$*_rev$$COUNT$$x; \
+	echo "Output: rev/$*_rev$$COUNT$$x"; done;

rtl/accum/tests/out_axis_fifo_tb.sv

@@ -0,0 +1,198 @@
+`timescale 1ns/1ps
+
+module tb_out_axis_fifo;
+
+    localparam int ACCUM_WIDTH = 32;
+    localparam int WINDOW_SIZE = 65;
+    localparam int PACKET_SIZE = 1024;
+
+    logic eth_clk_in;
+    logic acc_clk_in;
+    logic rst;
+
+    logic [31:0] smp_num;
+
+    logic [7:0]  s_axis_tdata;
+    logic        s_axis_tvalid;
+    logic        s_axis_tready;
+    logic        s_axis_tlast;
+
+    logic [ACCUM_WIDTH-1:0] acc_din;
+    logic                   din_valid;
+
+    logic readout_begin;
+
+    logic batch_req;
+    logic finish;
+
+    out_axis_fifo #(
+        .ACCUM_WIDTH(ACCUM_WIDTH),
+        .WINDOW_SIZE(WINDOW_SIZE),
+        .PACKET_SIZE(PACKET_SIZE)
+    ) dut (
+        .eth_clk_in    (eth_clk_in),
+        .acc_clk_in    (acc_clk_in),
+        .rst           (rst),
+        .smp_num       (smp_num),
+
+        .s_axis_tdata  (s_axis_tdata),
+        .s_axis_tvalid (s_axis_tvalid),
+        .s_axis_tready (s_axis_tready),
+        .s_axis_tlast  (s_axis_tlast),
+
+        .acc_din       (acc_din),
+        .din_valid     (din_valid),
+
+        .readout_begin (readout_begin),
+
+        .batch_req     (batch_req),
+        .finish        (finish)
+    );
+
+    // -----------------------------
+    // clocks
+    // -----------------------------
+    initial begin
+        eth_clk_in = 0;
+        forever #4 eth_clk_in = ~eth_clk_in;   // 125 MHz
+    end
+
+    initial begin
+        acc_clk_in = 0;
+        forever #3 acc_clk_in = ~acc_clk_in;   // ~166.7 MHz
+    end
+
+    // -----------------------------
+    // simple AXIS sink
+    // -----------------------------
+    initial begin
+        s_axis_tready = 1'b1;
+    end
+
+    // У DUT нет своей логики rd_en, поэтому для теста подадим её force-ом.
+    initial begin
+        force dut.rd_en = dut.s_axis_tvalid && s_axis_tready;
+    end
+
+    // -----------------------------
+    // helpers
+    // -----------------------------
+    task automatic do_reset();
+        begin
+            rst          = 1'b1;
+            readout_begin = 1'b0;
+            din_valid    = 1'b0;
+            acc_din      = '0;
+            smp_num      = '0;
+
+            repeat (10) @(posedge acc_clk_in);
+            rst = 1'b0;
+
+            repeat (10) @(posedge acc_clk_in);
+        end
+    endtask
+
+    task automatic pulse_readout_begin(input logic [31:0] smp_num_i);
+        begin
+            smp_num = smp_num_i;
+            @(posedge acc_clk_in);
+            readout_begin <= 1'b1;
+            @(posedge acc_clk_in);
+            readout_begin <= 1'b0;
+        end
+    endtask
+
+    task automatic send_random_words(input int unsigned n_words);
+        int unsigned i;
+        begin
+            for (i = 0; i < n_words; i++) begin
+                @(posedge acc_clk_in);
+                din_valid <= 1'b1;
+                acc_din   <= $urandom;
+            end
+
+            @(posedge acc_clk_in);
+            din_valid <= 1'b0;
+            acc_din   <= '0;
+        end
+    endtask
+
+    // Один запуск:
+    // 1) задаём smp_num
+    // 2) даём readout_begin
+    // 3) каждый раз, когда DUT просит batch_req, отправляем PACKET_SIZE слов
+    // 4) ждём finish
+    task automatic run_case(input logic [31:0] smp_num_i);
+        int batch_count;
+        begin
+            batch_count = 0;
+
+            $display("[%0t] run_case start, smp_num=%0d", $time, smp_num_i);
+
+            pulse_readout_begin(smp_num_i);
+
+            while (finish !== 1'b1) begin
+                @(posedge acc_clk_in);
+
+                if (batch_req) begin
+                    batch_count++;
+                    $display("[%0t] batch_req #%0d -> send %0d words",
+                             $time, batch_count, PACKET_SIZE / ACCUM_WIDTH * 8);
+                    
+                    // send packets to accomplish 1kb packet.
+                    send_random_words(PACKET_SIZE / ACCUM_WIDTH * 8);
+                end
+            end
+
+            $display("[%0t] run_case done, smp_num=%0d, batches=%0d, wr_cnt=%0d, wr_total=%0d",
+                     $time, smp_num_i, batch_count, dut.wr_cnt, dut.wr_total);
+
+            @(posedge acc_clk_in);
+        end
+    endtask
+
+    // -----------------------------
+    // monitor
+    // -----------------------------
+    int axis_byte_count;
+
+    always_ff @(posedge eth_clk_in or posedge rst) begin
+        if (rst) begin
+            axis_byte_count <= 0;
+        end else begin
+            if (s_axis_tvalid && s_axis_tready) begin
+                axis_byte_count <= axis_byte_count + 1;
+            end
+        end
+    end
+
+    // -----------------------------
+    // main
+    // -----------------------------
+    initial begin
+        // init
+        rst           = 1'b0;
+        readout_begin = 1'b0;
+        din_valid     = 1'b0;
+        acc_din       = '0;
+        smp_num       = '0;
+
+        // 1-й запуск
+        do_reset();
+        run_case(32'd17);
+
+        // 2-й запуск
+        do_reset();
+        run_case(32'd1024);
+
+        // 3-й запуск
+        do_reset();
+        run_case(32'd77777);
+        
+        do_reset();
+        repeat (50) @(posedge acc_clk_in);
+        $display("[%0t] ALL TESTS DONE", $time);
+        $finish;
+    end
+
+endmodule