代码如下：

1 //---------------------------------------------- 2 //复位信号产生，低有效 3 //异步复位，同步释放 4 input clk; 5 input rst_n; 6  7 reg rst_n1,rst_n2; 8  9 always @(posedge clk or negedge rst_n)10     if(!rst_n) rst_n1 <= 1'b0;11     else rst_n1 <= 1'b1;12 13 always @(posedge clk or negedge rst_n)                    14     if(!rst_n) rst_nr2 <= 1'b0;15     else rst_nr2 <= rst_nr1;16 17 assign sys_rst_n = rst_n2;