题解 | #使用握手信号实现跨时钟域数据传输#

`timescale 1ns/1ns
module data_driver(
	input clk_a,
	input rst_n,
	input data_ack,
	output reg [3:0]data,
	output reg data_req
	);

//用来计算接收完成后，5个clk后，data加1
reg [2:0] cnt;
always@(posedge clk_a or negedge rst_n)
  if(!rst_n)
    cnt <= 3'd0;
  else if(data_ack)
    cnt <= 3'd0;
  else 
    cnt <= cnt + 3'd1;

//data  0-7循环
//每次循环前，都有响应信号代表进入下一数据的发送
always@(posedge clk_a or negedge rst_n)
  if(!rst_n)
    data <= 4'd0;
  else if(data==4'd7)
    data <=4'd0;
  else if(cnt==3'd4 && data_ack)
    data <= data + 4'd1;
  else
    data <= 4'd0;

//输出有效信号在被接收成功前，一直拉高
always@(posedge clk_a or negedge rst_n)
  if(!rst_n)
    data_req<= 1'd0;
  else if(data_ack)
    data_req <= 1'd0;
  else if(cnt==3'd4)
    data_req <= 1'd1;

endmodule



module data_receiver(
	input clk_b,
	input rst_n,
	input [3:0] data,
	input  data_req,
	output reg data_ack
	);

//接收响应信号只拉高一个周期
always@(posedge clk_b or negedge rst_n)
  if(!rst_n)
    data_ack <= 1'd0;
  else if(data_req)
    data_ack <= 1'd1;
  else 
    data_ack <= 1'd0;

endmodule