51单片机rfid读卡程序

以下是51单片机通过RFID读卡器读取RFID卡片的示例代码：

#include <reg52.h> // 引入单片机头文件
sbit beep=P1^5; // 蜂鸣器引脚
sbit led=P1^4; // LED引脚
unsigned char code table[16] = {0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E,0x0F}; // RFID卡片ID码的映射表

void delay(unsigned int i) // 延时函数
{
    unsigned int j,k;
    for(j=i;j>0;j--)
        for(k=120;k>0;k--);
}

void write(unsigned char addr, unsigned char dat) // 写入数据到RC522寄存器
{
    P0 = addr;
    P2 &= ~0x01;
    P0 = dat;
    P2 |= 0x01;
}

unsigned char read(unsigned char addr) // 从RC522寄存器读取数据
{
    P0 = addr|0x80;
    P2 &= ~0x01;
    delay(1);
    P2 |= 0x01;
    delay(1);
    return P0;
}

void init() // 初始化RC522
{
    write(0x01,0x0F); // 复位
    write(0x2A,0x8D); // 开启天线
    write(0x2B,0x3E); // 天线增益
    write(0x2D,0x30); // 信号强度调节
    write(0x2C,0); // 关闭M1卡片检测
}

unsigned char request() // 寻卡
{
    unsigned char status;
    unsigned int i;
    write(0x0D,0x07);
    status = read(0x0D);
    if(status == 0x07) // 寻到卡
    {
        status = 0;
        write(0x0D,0x00);
        write(0x0E,0x0C);
        write(0x0F,0x00);
        for(i=0;i<1000;i++) // 等待卡片回应
        {
            status = read(0x0F);
            if(status == 0x18)
                break;
            delay(1);
        }
        if(status == 0x18) // 卡片已经准备好
        {
            write(0x0D,0x08);
            status = 1;
        }
    }
    return status;
}

unsigned char anticoll() // 防冲突
{
    unsigned char i,status;
    unsigned char cardid[5];
    write(0x0D,0x01);
    status = read(0x0D);
    if(status == 0x01) // 防冲突成功
    {
        status = 0;
        cardid[0] = read(0x16);
        cardid[1] = read(0x17);
        cardid[2] = read(0x18);
        cardid[3] = read(0x19);
        cardid[4] = read(0x1A);
        for(i=0;i<4;i++)
            status ^= cardid[i];
        if(status != cardid[4]) // 校验失败
            status = 0;
    }
    return status;
}

void main()
{
    unsigned char i,cardid[5];
    TMOD = 0x01;
    TH0 = 0xFC;
    TL0 = 0x18;
    TR0 = 1;
    ET0 = 1;
    EA = 1;
    init();
    while(1)
    {
        if(request()) // 寻卡成功
        {
            if(anticoll()) // 防冲突成功
            {
                for(i=0;i<5;i++)
                    cardid[i] = read(0x16+i);
                for(i=0;i<4;i++)
                {
                    P0 = table[cardid[i] >> 4];
                    delay(10);
                    P0 = table[cardid[i] & 0x0F];
                    delay(10);
                }
                P0 = 0x00;
                delay(100);
                led = !led;
                beep = 1;
                delay(100);
                beep = 0;
            }
        }
    }
}

void timer0() interrupt 1 // 定时器中断
{
    TH0 = 0xFC;
    TL0 = 0x18;
    beep = !beep;
}

这段代码使用了RC522 RFID模块进行卡片的读取，通过不断的寻卡和防冲突操作，最终可以将读取到的RFID卡片ID码输出到P0口，并且控制LED和蜂鸣器进行状态的提示。其中，需要注意的是RC522模块的引脚连接和初始化操作。