安路FPGA_LED闪烁

C++
module led_test(
    //input
    input clk,//时钟 25M
    input rst_n,//复位,高电平复位
   
    //output
        output reg [3:0]led
);
 
reg [23:0]cnt_250ms;
parameter TIME_250ms = 24'b0101_1111_0101_1110_0001_0000;
 
always@(posedge clk or negedge rst_n) begin
    if (rst_n == 1'b0)
        cnt_250ms <= 24'd0;
    else if (cnt_250ms == TIME_250ms - 1)
        cnt_250ms <= 24'd0;
    else
        cnt_250ms <= cnt_250ms + 24'd1;
end
always@(posedge clk or negedge rst_n) begin
    if (rst_n == 1'b0)
        led <= 8'b0000;
    else if (cnt_250ms ==TIME_250ms - 1)
        case(led)
        8'b0000: led <= 8'b1111;
        8'b1111: led <= 8'b0000;
       
        default: led <= 8'b0000;
        endcase
    else
        led <= led;
end
 
endmodule