51单片机红绿灯仿真

以下是基于51单片机的红绿灯仿真的步骤和代码：

1. 确定硬件电路，包括LED灯、数码管、按键等元件的连接方式和电路图。

2. 在Keil中新建一个工程，编写C语言程序。

3. 在程序中定义各个元件的引脚，例如LED灯的引脚为P1.0，数码管的引脚为P2。

4. 编写程序实现红绿灯的交替显示，可以使用定时器和外部中断来控制灯的状态转换。

5. 编写程序实现数码管的倒计时显示，可以使用定时器和计数器来实现。

6. 编写程序实现按键的检测和响应，例如按下按键可以切换灯的状态或者停止倒计时。

以下是示例代码：

#include <reg52.h>

sbit LED_RED = P1^0;
sbit LED_YELLOW = P1^1;
sbit LED_GREEN = P1^2;
sbit KEY = P3^2;
sbit DIGIT_A = P2^0;
sbit DIGIT_B = P2^1;
sbit DIGIT_C = P2^2;
sbit DIGIT_D = P2^3;
sbit DIGIT_E = P2^4;
sbit DIGIT_F = P2^5;
sbit DIGIT_G = P2^6;
sbit DIGIT_DP = P2^7;

unsigned char code DIGIT_TABLE[] = {
    0x3F, 0x06, 0x5B, 0x4F, 0x66, 0x6D, 0x7D, 0x07, 0x7F, 0x6F
};

unsigned char code TIME_TABLE[] = {
    60, 50, 40, 30, 20, 10
};

unsigned char current_time = 0;
unsigned char current_state = 0;

void delay(unsigned int ms) {
    unsigned int i, j;
    for (i = 0; i < ms; i++) {
        for (j = 0; j < 110; j++);
    }
}

void display_digit(unsigned char digit, unsigned char dp) {
    DIGIT_A = (digit & 0x01) ? 0 : 1;
    DIGIT_B = (digit & 0x02) ? 0 : 1;
    DIGIT_C = (digit & 0x04) ? 0 : 1;
    DIGIT_D = (digit & 0x08) ? 0 : 1;
    DIGIT_E = (digit & 0x10) ? 0 : 1;
    DIGIT_F = (digit & 0x20) ? 0 : 1;
    DIGIT_G = (digit & 0x40) ? 0 : 1;
    DIGIT_DP = dp ? 0 : 1;
}

void display_time(unsigned char time) {
    unsigned char digit1, digit2;
    digit1 = time / 10;
    digit2 = time % 10;
    display_digit(DIGIT_TABLE[digit1], 0);
    delay(5);
    display_digit(DIGIT_TABLE[digit2], 1);
    delay(5);
}

void timer0_isr() interrupt 1 {
    TH0 = (65536 - 50000) / 256;
    TL0 = (65536 - 50000) % 256;
    current_time--;
    if (current_time == 0) {
        current_state++;
        if (current_state > 2) {
            current_state = 0;
        }
        switch (current_state) {
            case 0:
                LED_RED = 1;
                LED_YELLOW = 0;
                LED_GREEN = 0;
                current_time = TIME_TABLE[0];
                break;
            case 1:
                LED_RED = 1;
                LED_YELLOW = 1;
                LED_GREEN = 0;
                current_time = TIME_TABLE[1];
                break;
            case 2:
                LED_RED = 0;
                LED_YELLOW = 0;
                LED_GREEN = 1;
                current_time = TIME_TABLE[2];
                break;
        }
    }
}

void main() {
    TMOD = 0x01;
    TH0 = (65536 - 50000) / 256;
    TL0 = (65536 - 50000) % 256;
    ET0 = 1;
    EA = 1;
    TR0 = 1;
    while (1) {
        display_time(current_time);
        if (KEY == 0) {
            delay(10);
            if (KEY == 0) {
                current_state = 0;
                LED_RED = 1;
                LED_YELLOW = 0;
                LED_GREEN = 0;
                current_time = TIME_TABLE[0];
                while (KEY == 0);
            }
        }
    }
}