source code

module key_beep(
    input sys_clk,
    input sys_rst_n,
    input key,
    output reg beep
    );
reg [19:0]cnt;
reg key_delay_20ms;
reg key_delay_20ms_last;
reg key_last;
always@(posedge sys_clk or negedge sys_rst_n)
begin
    if(!sys_rst_n)
    begin
        cnt<=20'b0;
        key_last<=1;
    end
    else 
    begin
        key_last<=key;
        if(key_last!=key)
            cnt<=20'd0;
        else 
            cnt<=(cnt==20'd100_0000)?cnt:cnt+1;
    end
end
always@(posedge sys_clk or negedge sys_rst_n)
begin
    if(!sys_rst_n)
    begin
        key_delay_20ms<=1;
        key_delay_20ms_last<=1;
    end
    else 
    begin
        key_delay_20ms_last<=key_delay_20ms;
        if(key_delay_20ms_last==0 && key_delay_20ms==1)
            beep<=~beep;
        else
            beep<=beep;
        if(cnt==20'd100_0000)
            key_delay_20ms<=key;
        else
            key_delay_20ms<=key_delay_20ms;
     end
end
endmodule

xdc文件

set_property -dict {PACKAGE_PIN M14 IOSTANDARD LVCMOS33} [get_ports {beep}]
set_property -dict {PACKAGE_PIN L14 IOSTANDARD LVCMOS33} [get_ports {key}]
set_property -dict {PACKAGE_PIN U18 IOSTANDARD LVCMOS33} [get_ports sys_clk]
set_property -dict {PACKAGE_PIN N16 IOSTANDARD LVCMOS33} [get_ports sys_rst_n]