Verilog 实现十字路口交通灯控制器 - 倒计时显示

以下是一个可能的十字路口交通灯控制器的 Verilog 代码。该代码使用一个时钟信号来控制交通灯的状态，并使用一个计数器来跟踪每个状态的持续时间。数码管模块用于显示一个方向上的允许通行或禁止通行的时间。

module traffic_control(
    input clk,
    output reg east_red,
    output reg east_yellow,
    output reg east_green,
    output reg north_red,
    output reg north_yellow,
    output reg north_green,
    output [3:0] countdown
);

// 定义状态
parameter RED = 2'b00;
parameter YELLOW = 2'b01;
parameter GREEN = 2'b10;

// 定义持续时间
parameter RED_TIME = 8;
parameter YELLOW_TIME = 3;
parameter GREEN_TIME = 5;

// 定义计数器和状态变量
reg [2:0] counter;
reg [1:0] east_state;
reg [1:0] north_state;

// 初始化状态和计数器
initial begin
    counter = 0;
    east_state = GREEN;
    north_state = RED;
end

// 每个时钟周期更新状态和计数器
always @(posedge clk) begin
    // 更新计数器
    counter <= counter + 1;

    // 根据计数器和当前状态确定下一个状态
    case ({east_state, north_state})
        {GREEN, RED}: begin
            if (counter == GREEN_TIME * 2) begin
                east_state <= YELLOW;
                counter <= 0;
            end
        end
        {YELLOW, RED}: begin
            if (counter == YELLOW_TIME * 2) begin
                east_state <= RED;
                north_state <= GREEN;
                counter <= 0;
            end
        end
        {RED, GREEN}: begin
            if (counter == GREEN_TIME * 2) begin
                north_state <= YELLOW;
                counter <= 0;
            end
        end
        {RED, YELLOW}: begin
            if (counter == YELLOW_TIME * 2) begin
                north_state <= RED;
                east_state <= GREEN;
                counter <= 0;
            end
        end
        default: begin
            counter <= 0;
        end
    endcase
end

// 根据当前状态设置交通灯信号
assign east_red = (east_state == RED);
assign east_yellow = (east_state == YELLOW);
assign east_green = (east_state == GREEN);
assign north_red = (north_state == RED);
assign north_yellow = (north_state == YELLOW);
assign north_green = (north_state == GREEN);

// 数码管模块
seven_segment_display sseg(
    .value(countdown)
);

// 根据当前状态和计数器确定允许通行或禁止通行的时间，并将其显示在数码管上
always @(posedge clk) begin
    case ({east_state, north_state})
        {GREEN, RED}: begin
            countdown <= GREEN_TIME - (counter / 2);
        end
        {YELLOW, RED}: begin
            countdown <= YELLOW_TIME - (counter / 2);
        end
        {RED, GREEN}: begin
            countdown <= GREEN_TIME - (counter / 2);
        end
        {RED, YELLOW}: begin
            countdown <= YELLOW_TIME - (counter / 2);
        end
        default: begin
            countdown <= 0;
        end
    endcase
end

endmodule

该代码使用一个名为seven_segment_display的数码管模块，该模块将一个4位二进制数显示为七段数码管上的数字。该模块的代码如下：

module seven_segment_display(
    input [3:0] value,
    output reg a,
    output reg b,
    output reg c,
    output reg d,
    output reg e,
    output reg f,
    output reg g
);

// 数码管数字编码
parameter ZERO = 7'b1111110;
parameter ONE = 7'b0110000;
parameter TWO = 7'b1101101;
parameter THREE = 7'b1111001;
parameter FOUR = 7'b0110011;
parameter FIVE = 7'b1011011;
parameter SIX = 7'b1011111;
parameter SEVEN = 7'b1110000;
parameter EIGHT = 7'b1111111;
parameter NINE = 7'b1111011;

// 根据输入值设置数码管输出
always @(*) begin
    case (value)
        4'b0000: begin
            a = 1;
            b = 1;
            c = 1;
            d = 1;
            e = 1;
            f = 1;
            g = 0;
        end
        4'b0001: begin
            a = 0;
            b = 1;
            c = 1;
            d = 0;
            e = 0;
            f = 0;
            g = 0;
        end
        4'b0010: begin
            a = 1;
            b = 1;
            c = 0;
            d = 1;
            e = 1;
            f = 0;
            g = 1;
        end
        4'b0011: begin
            a = 1;
            b = 1;
            c = 1;
            d = 1;
            e = 0;
            f = 0;
            g = 1;
        end
        4'b0100: begin
            a = 0;
            b = 1;
            c = 1;
            d = 0;
            e = 0;
            f = 1;
            g = 1;
        end
        4'b0101: begin
            a = 1;
            b = 0;
            c = 1;
            d = 1;
            e = 0;
            f = 1;
            g = 1;
        end
        4'b0110: begin
            a = 1;
            b = 0;
            c = 1;
            d = 1;
            e = 1;
            f = 1;
            g = 1;
        end
        4'b0111: begin
            a = 1;
            b = 1;
            c = 1;
            d = 0;
            e = 0;
            f = 0;
            g = 0;
        end
        4'b1000: begin
            a = 1;
            b = 1;
            c = 1;
            d = 1;
            e = 1;
            f = 1;
            g = 1;
        end
        4'b1001: begin
            a = 1;
            b = 1;
            c = 1;
            d = 1;
            e = 0;
            f = 1;
            g = 1;
        end
        default: begin
            a = 0;
            b = 0;
            c = 0;
            d = 0;
            e = 0;
            f = 0;
            g = 0;
        end
    endcase
end

endmodule