本實(shí)驗(yàn)基于xilinx ARTIX-7芯片驗(yàn)證實(shí)現(xiàn)，有時(shí)間有興趣的朋友可在其他FPGA芯片上實(shí)現(xiàn)驗(yàn)證。

當(dāng)大家看到《xilinx verilog語(yǔ)法技巧(三)–RAM的初始化》文章的時(shí)候很多人認(rèn)為initial語(yǔ)句，$readmemb語(yǔ)句均是不可綜合語(yǔ)句（只能用來(lái)寫(xiě)測(cè)試文件），但是xilinx的綜合器已經(jīng)悄然改變了這一點(diǎn)。

rams_init_file源碼：

// Initializing Block RAM from external data file
// Binary data
// File: rams_init_file.v

module rams_init_file (clk, we, addr, din, dout);
input clk;
input we;
input [5:0] addr;
input [31:0] din;
output [31:0] dout;

reg [31:0] ram [0:63];
reg [31:0] dout;

initial begin
$readmemb("rams_init_file.data",ram);
end

always @(posedge clk)
begin
  if (we)
     ram[addr] <= din;
  dout <= ram[addr];
end endmodule

rams_init_file.data源文件：

00001110110000011001111011000110
00101011001011010101001000100011
01110100010100011000011100001111
01000001010000100101001110010100
00001001101001111111101000101011
00101101001011111110101010100111
11101111000100111000111101101101
10001111010010011001000011101111
00000001100011100011110010011111
11011111001110101011111001001010
11100111010100111110110011001010
11000100001001101100111100101001
10001011100101011111111111100001
11110101110110010000010110111010
01001011000000111001010110101110
11100001111111001010111010011110
01101111011010010100001101110001
01010100011011111000011000100100
11110000111101101111001100001011
10101101001111010100100100011100
01011100001010111111101110101110
01011101000100100111010010110101
11110111000100000101011101101101
11100111110001111010101100001101
01110100000011101111111000011111
00010011110101111000111001011101
01101110001111100011010101101111
10111100000000010011101011011011
11000001001101001101111100010000
00011111110010110110011111010101
01100100100000011100100101110000
10001000000100111011001010001111
11001000100011101001010001100001
10000000100111010011100111100011
11011111010010100010101010000111
10000000110111101000111110111011
10110011010111101111000110011001
00010111100001001010110111011100
10011100101110101111011010110011
01010011101101010001110110011010
01111011011100010101000101000001
10001000000110010110111001101010
11101000001101010000111001010110
11100011111100000111110101110101
01001010000000001111111101101111
00100011000011001000000010001111
10011000111010110001001011100100
11111111111011110101000101000111
11000011000101000011100110100000
01101101001011111010100011101001
10000111101100101001110011010111
11010110100100101110110010100100
01001111111001101101011111001011
11011001001101110110000100110111
10110110110111100101110011100110
10011100111001000010111111010110
00000000001011011111001010110010
10100110011010000010001000011011
11001010111111001001110001110101
00100001100010000111000101001000
00111100101111110001101101111010
11000010001010000000010100100001
11000001000110001101000101001110
10010011010100010001100100100111

tb_rams_init_file測(cè)試頂層文件：

`timescale 1ns / 1ps
module tb_rams_init_file(
       input clk,
       input reset,
       output [2:0] led_rgb0,
       output [2:0] led_rgb1,
       output [2:0] led_rgb2,
       output [2:0] led_rgb3
        );
reg [5:0] addr;
wire  [31:0] dout;
reg [27:0] cnt;

assign led_rgb0 = dout[2:0];
assign led_rgb1 = dout[5:3];
assign led_rgb2 = dout[8:6];
assign led_rgb3 = dout[11:9];

always @(posedge clk ) begin
  if(reset==1'b1) begin
    cnt   <= 28'd0;
    addr <= 0;
  end
  else if(cnt == 28'd100000000)begin//1s
    cnt <= 28'd0;
    addr <= addr +1;
  end
  else begin
    cnt   <= cnt + 1;
    addr <= addr;
  end
end
rams_init_file u_rams_init_file(
               .clk(clk), 
               .we(1'b0), 
               .addr(addr), 
               .din(32'b0), 
               .dout(dout));
endmodule

約束文件(根據(jù)自己板卡)：

set_property PACKAGE_PIN E3 [get_ports clk]
set_property IOSTANDARD LVCMOS33 [get_ports clk]

set_property PACKAGE_PIN D9 [get_ports reset]
set_property IOSTANDARD LVCMOS33 [get_ports reset]

set_property PACKAGE_PIN E1 [get_ports led_rgb0[0]]
set_property IOSTANDARD LVCMOS33 [get_ports led_rgb0[0]]

set_property PACKAGE_PIN G6 [get_ports led_rgb0[1]]
set_property IOSTANDARD LVCMOS33 [get_ports led_rgb0[1]]

set_property PACKAGE_PIN F6 [get_ports led_rgb0[2]]
set_property IOSTANDARD LVCMOS33 [get_ports led_rgb0[2]]

set_property PACKAGE_PIN G4 [get_ports led_rgb1[0]]
set_property IOSTANDARD LVCMOS33 [get_ports led_rgb1[0]]

set_property PACKAGE_PIN G3 [get_ports led_rgb1[1]]
set_property IOSTANDARD LVCMOS33 [get_ports led_rgb1[1]]

set_property PACKAGE_PIN J4 [get_ports led_rgb1[2]]
set_property IOSTANDARD LVCMOS33 [get_ports led_rgb1[2]]

set_property PACKAGE_PIN H4 [get_ports led_rgb2[0]]
set_property IOSTANDARD LVCMOS33 [get_ports led_rgb2[0]]

set_property PACKAGE_PIN J3 [get_ports led_rgb2[1]]
set_property IOSTANDARD LVCMOS33 [get_ports led_rgb2[1]]

set_property PACKAGE_PIN J2 [get_ports led_rgb2[2]]
set_property IOSTANDARD LVCMOS33 [get_ports led_rgb2[2]]

set_property PACKAGE_PIN K2 [get_ports led_rgb3[0]]
set_property IOSTANDARD LVCMOS33 [get_ports led_rgb3[0]]

set_property PACKAGE_PIN K1 [get_ports led_rgb3[1]]
set_property IOSTANDARD LVCMOS33 [get_ports led_rgb3[1]]

set_property PACKAGE_PIN H6 [get_ports led_rgb3[2]]
set_property IOSTANDARD LVCMOS33 [get_ports led_rgb3[2]]

審核編輯：劉清