请用verilog帮我写一个由八个八段数码管显示的倒计时器项目

好的，以下是一个简单的由八个八段数码管显示的倒计时器项目的Verilog代码：

module countdown_timer(
    input clk,
    input reset,
    output reg [7:0] seg_a,
    output reg [7:0] seg_b,
    output reg [7:0] seg_c,
    output reg [7:0] seg_d,
    output reg [7:0] seg_e,
    output reg [7:0] seg_f,
    output reg [7:0] seg_g,
    output reg [7:0] dp
);

reg [24:0] counter = 25_000_000; // 1秒钟的计数器
reg [23:0] countdown = 60_000; // 60秒倒计时计数器

always @(posedge clk) begin
    if (reset) begin
        counter <= 25_000_000;
        countdown <= 60_000;
    end else begin
        counter <= counter - 1;
        if (counter == 0) begin
            counter <= 25_000_000;
            countdown <= countdown - 1;
        end
    end
end

always @(countdown) begin
    case (countdown)
        60_000: begin
            seg_a <= 8'hc0;
            seg_b <= 8'h60;
            seg_c <= 8'h60;
            seg_d <= 8'h06;
            seg_e <= 8'h3f;
            seg_f <= 8'h7d;
            seg_g <= 8'h00;
            dp <= 8'h00;
        end
        59_000: begin
            seg_a <= 8'h30;
            seg_b <= 8'h18;
            seg_c <= 8'h18;
            seg_d <= 8'h06;
            seg_e <= 8'h3f;
            seg_f <= 8'h7d;
            seg_g <= 8'h00;
            dp <= 8'h00;
        end
        // 以此类推，根据倒计时的数值依次设置显示的数码管的值
        // ...
        0: begin
            seg_a <= 8'h00;
            seg_b <= 8'h00;
            seg_c <= 8'h00;
            seg_d <= 8'h00;
            seg_e <= 8'h00;
            seg_f <= 8'h00;
            seg_g <= 8'h00;
            dp <= 8'h00;
        end
    endcase
end

endmodule

这个倒计时器每次启动时会从60秒开始倒计时，并且会在八个八段数码管上显示倒计时的数值。倒计时结束后，所有的数码管都会被清零。您可以根据需要修改计数器的初始值和倒计时结束后的显示值。