写一个基于FPGA的复杂数字时钟代码

以下是一个基于FPGA的复杂数字时钟代码的示例：

module complex_clock(
    input clk,
    input rst,
    output reg [7:0] hour,
    output reg [7:0] minute,
    output reg [7:0] second
);

reg [3:0] hour_tens;
reg [3:0] hour_ones;
reg [3:0] min_tens;
reg [3:0] min_ones;
reg [3:0] sec_tens;
reg [3:0] sec_ones;
reg [1:0] div_cnt;

always @(posedge clk or posedge rst) begin
    if (rst) begin
        hour_tens <= 4'b0000;
        hour_ones <= 4'b0000;
        min_tens <= 4'b0000;
        min_ones <= 4'b0000;
        sec_tens <= 4'b0000;
        sec_ones <= 4'b0000;
        div_cnt <= 2'b00;
    end else begin
        div_cnt <= div_cnt + 1;
        if (div_cnt == 2'b11) begin
            div_cnt <= 2'b00;
            second <= second + 1;
            if (second == 8'h60) begin
                second <= 8'h00;
                minute <= minute + 1;
                if (minute == 8'h60) begin
                    minute <= 8'h00;
                    hour <= hour + 1;
                    if (hour == 8'h24) begin
                        hour <= 8'h00;
                    end
                end
            end
        end
    end
end

always @(hour, minute, second) begin
    hour_tens <= hour[7:4];
    hour_ones <= hour[3:0];
    min_tens <= minute[7:4];
    min_ones <= minute[3:0];
    sec_tens <= second[7:4];
    sec_ones <= second[3:0];
end

endmodule

上述代码实现了一个复杂的数字时钟，可以显示时、分、秒，同时还实现了时钟的计时功能，每秒钟加1。在代码中，使用了时钟分频的方法来实现计时功能，通过一个计数器 div_cnt 来记录时钟周期数，当计数器达到一定值时，对时、分、秒进行更新。同时，使用了时钟分频器来将时、分、秒分别拆分成十位和个位，方便数码管显示。