51单片机rfid-rc522读卡器

51单片机可以通过SPI接口与RFID-RC522读卡器进行通信，实现读取RFID卡片信息的功能。以下是一个简单的代码示例：

#include <reg51.h>

#define uchar unsigned char
#define uint unsigned int

sbit SDA = P1^0; //SDA引脚
sbit SCK = P1^1; //SCK引脚
sbit CS = P1^2; //CS引脚

uchar Read_MFRC522(uchar addr)
{
    uchar val;
    CS = 0; //拉低片选信号
    SCK = 0; //拉低时钟信号
    SDA = ((addr<<1)&0x7E)|0x80; //发送地址+读命令
    SCK = 1; //拉高时钟信号
    val = SDA; //读取数据
    SCK = 0; //拉低时钟信号
    CS = 1; //拉高片选信号
    return val;
}

void Write_MFRC522(uchar addr, uchar val)
{
    CS = 0; //拉低片选信号
    SCK = 0; //拉低时钟信号
    SDA = (addr<<1)&0x7E; //发送地址+写命令
    SCK = 1; //拉高时钟信号
    SDA = val; //发送数据
    SCK = 0; //拉低时钟信号
    CS = 1; //拉高片选信号
}

void Init_MFRC522()
{
    Write_MFRC522(0x01, 0x0F); //复位RC522
    Write_MFRC522(0x2A, 0x8D); //开启天线
    Write_MFRC522(0x2B, 0x3E); //调节天线增益
    Write_MFRC522(0x2D, 0x30); //调节信号充放电时间
    Write_MFRC522(0x2C, 0); //清空内部缓冲区
}

uchar Request_MFRC522(uchar reqMode, uchar *TagType)
{
    uchar status;
    uint backBits;
    Write_MFRC522(0x0D, 0x01); //将CRC计算器初始值设为0x01
    TagType[0] = reqMode;
    status = RC522_ToCard(0x0C, TagType, 1, TagType, &backBits);
    if ((status != 0) || (backBits != 0x10))
        status = 1;
    return status;
}

uchar RC522_ToCard(uchar cmd, uchar *sendData, uchar sendLen, uchar *backData, uint *backLen)
{
    uchar status = 0;
    uchar irqEn = 0x00;
    uchar waitIRq = 0x00;
    uchar lastBits;
    uchar n;
    uint i;
    switch (cmd)
    {
        case 0x0C:
            irqEn = 0x77;
            waitIRq = 0x30;
            break;
    }
    Write_MFRC522(0x02, irqEn | 0x80);
    Write_MFRC522(0x04, waitIRq | 0x80);
    Write_MFRC522(0x01, 0x00);
    Write_MFRC522(0x0D, 0x00);
    if (sendData != NULL)
    {
        Write_MFRC522(0x09, sendLen);
        Write_MFRC522(0x08, 0x02);
        for (i = 0; i < sendLen; i++)
            Write_MFRC522(0x09, sendData[i]);
    }
    Write_MFRC522(0x01, cmd);
    if (cmd == 0x0C)
        Write_MFRC522(0x0E, 0x80);
    i = 2000;
    while (1)
    {
        n = Read_MFRC522(0x04);
        i--;
        if ((i == 0) || (n & 0x01))
            break;
    }
    if (i == 0)
        return 1;
    n = Read_MFRC522(0x06);
    if (n & 0x30)
        return 2;
    if (cmd == 0x0C)
    {
        lastBits = Read_MFRC522(0x05) & 0x07;
        if (lastBits != 0)
            *backLen = (backBits - 1) * 8 + lastBits;
        else
            *backLen = backBits * 8;
        if (backBits == 0)
            backBits = 1;
        if (backBits > 16)
            backBits = 16;
        for (i = 0; i < backBits; i++)
            backData[i] = Read_MFRC522(0x09);
    }
    return status;
}

uchar Anticoll_MFRC522(uchar *serNum)
{
    uchar status;
    uchar i;
    uchar serNumCheck = 0;
    uint unLen;
    Write_MFRC522(0x0D, 0x00);
    serNum[0] = 0x93;
    serNum[1] = 0x20;
    status = RC522_ToCard(0x93, serNum, 2, serNum, &unLen);
    if (status == 0)
    {
        for (i = 0; i < 4; i++)
            serNumCheck ^= serNum[i];
        if (serNumCheck != serNum[i])
            status = 1;
    }
    return status;
}

void main()
{
    uchar i;
    uchar status;
    uchar str[MAX_LEN];
    uchar RC_size;
    uchar RC_data[MAX_LEN];
    Init_MFRC522();
    while (1)
    {
        status = Request_MFRC522(0x52, str);
        if (status == 0)
            status = Anticoll_MFRC522(str);
        if (status == 0)
        {
            for (i = 0; i < 4; i++)
                printf("%02X", str[i]);
            printf("\n");
        }
    }
}

该代码中定义了一些常用的宏和变量，如SDA、SCK和CS引脚的定义，以及读取和写入数据的函数。在主函数中，首先初始化RC522读卡器，然后在循环中不断尝试读取RFID卡片的信息，如果成功读取到卡片信息，则将卡片ID输出到串口。需要注意的是，这里只演示了读取RFID卡片ID的功能，如果需要读取更多的卡片信息（如卡片类型、卡片数据等），需要根据RC522读卡器的数据手册进行相应的配置和操作。