题解 | 边沿检测
边沿检测
https://www.nowcoder.com/practice/fed4247d5ef64ac68c20283ebace11f4
`timescale 1ns/1ns module edge_detect( input clk, input rst_n, input a, output reg rise, output reg down ); reg a_dly; always@(posedge clk or negedge rst_n) begin if(!rst_n) begin a_dly <= 1'b0; end else begin a_dly <= a; end end always@(posedge clk or negedge rst_n) begin if(!rst_n) begin rise <= 1'b0; down <= 1'b0; end else if(a & !a_dly) begin rise <= 1'b1; down <= 1'b0; end else if(!a & a_dly) begin rise <= 1'b0; down <= 1'b1; end else //这两句话必须加，不然rise和down会进入不定态，养成良好编程习惯 begin rise <= 1'b0; down <= 1'b0; end end endmodule
