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 pre_a1; reg pre_a2; always@(posedge clk or negedge rst_n) begin if(!rst_n) begin pre_a1 <= 1'b0; pre_a2 <= 1'b0; end else begin pre_a1 <= a; pre_a2 <= pre_a1; end end // 当 输入 a 有不确定值出现的时候，rise 和 down 的值应该是0，而非不确定 //注意这里打 always@(posedge clk or negedge rst_n) begin if(!rst_n) begin rise <= 1'b0; down <= 1'b0; end else if(~a & pre_a1) begin rise <= 1'b0; down <= 1'b1; end else if(~pre_a1 & a) begin rise <= 1'b1; down <= 1'b0; end else begin rise <= 1'b0; down <= 1'b0; end end endmodule
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