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以前没接触过FPGA,目前只会一个always，像什么wire啊什么assign什么的还不知道什么意思。

写了个按键检测程序，有按下及松手的检测。

功能实现了，只是不知道这样写会有什么问题。

先谢谢各位了。

以下是代码：

module key(sys_clk, sys_rstn, led, key);

//输入/输出信号定义
input  key;
input  sys_clk;
input  sys_rstn;
output led;

//寄存器定义
reg [19:0] delay_cnt;
reg key_pressed;
reg key_stat;
reg led;

//逻辑部分
always@(posedge sys_clk or negedge sys_rstn)
    begin
        if (!sys_rstn)
            begin
                led<=1'b1;
                key_stat<=1'b0;
                delay_cnt<=20'h0;
            end
        else
            begin
                key_stat<=~key;
                if(key_stat)
                    begin

 //检测到按键按下，延时一段时间后如果依然为按下状态则判定为按键真实按下了。置key_pressed为1.
                        if (delay_cnt==20'hfffff)
                            begin
                                delay_cnt<=20'h0;
                                key_pressed<=1'b1;
                            end
                        else
                            begin
                                led<=led;
                                delay_cnt<=delay_cnt+1'b1;
                            end
                    end
                else
                    begin

                        //在前一状态为按键按下且松手一段时间后判定为真实松开了。
                        if(key_pressed)
                            begin
                                led<=led;
                                delay_cnt<=delay_cnt+1'b1;
                                if(delay_cnt==20'hfffff)  
                                    begin
                                        delay_cnt<=20'b0;
                                        key_pressed<=1'b0;
                                        led<=~led;
                                    end
                                else
                                    led<=led;
                            end
                    else
                        led<=led;
                end
        end
    end

endmodule