????RFID-RC522是一個淘寶上比較常見的一個識別RFID的一個模塊。他可以做到對RFID的讀寫。
????MF RC522 是應用於13.56MHz 非接觸式通信中高集成度讀寫卡系列芯片中的一員。是NXP公司針對“三表”應用推出的一款低電壓、低成本、體積小的非接觸式讀寫卡芯片，是智能儀表和便攜 式手持設備研發的較好選擇

RFID讀寫卡的過程

????讀寫卡主要有五個步驟：尋卡，防沖突，選卡，認證，讀/寫卡。

尋卡

// REQ_ALL代表尋天線區內所有卡，TagType為返回的卡的類型
status= PcdRequest( REQ_ALL , TagType );

TagType返回的卡類型有：
0x4400 = Mifare_UltraLight
0x0400 = Mifare_One(S50)
0x0200 = Mifare_One(S70)
0x0800 = Mifare_Pro(X)
0x4403 = Mifare_DESFire

防沖突

if(!status)
{
    status = PcdAnticoll(SelectedSnr);
    // ......
}

認證

if(!status)
{
    // 認證
    snr = 1;    // 扇區號1
    status = PcdAuthState(KEYA, (snr*4+3), DefaultKey, SelectedSnr);    // 校驗1扇區密碼，密碼位於每一扇區第3塊
    // ......
}

四個參數分別是：驗證A密鑰，塊地址，扇區密碼，卡序列號

讀寫卡

if(!status)
{
    //讀寫卡
    status = PcdRead((snr*4+0), buf);   // 讀卡，讀取1扇區0塊數據到buf[0]-buf[16]
    status = PcdWrite((snr*4+0), "way2");   // 寫卡，將buf[0]-buf[16]寫入1扇區0塊
    if(!status) 
    {
        //讀寫成功
        printf("read finish!\n");
        printf("讀到的值是： %s\n",buf);
        WaitCardOff();
    }
}
 

代碼

以下為核心代碼：
main.c

#include "stm32f10x.h"
#include "delay.h"
#include "bsp_usart.h"
#include "RC522.h"

int main()
{
    char status;
    unsigned char snr, buf[16], TagType[2], SelectedSnr[4], DefaultKey[6] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
    
    delay_init();
    usart_init();
    
    PcdInit();
    PcdReset();
    PcdAntennaOff();
    PcdAntennaOn();
    M500PcdConfigISOType( ‘A‘ );

    printf( "init over!\n" );
    while(1){
        // 尋卡
        status= PcdRequest( REQ_ALL , TagType );    // REQ_ALL代表尋天線區內所有卡。TagType為返回的卡類型
        if(!status)
        {
            // 防沖突
            status = PcdAnticoll(SelectedSnr);
            if(!status)
            {
                // 選卡
                status=PcdSelect(SelectedSnr);
                if(!status)
                {
                    // 認證
                    snr = 1;    // 扇區號1
                    status = PcdAuthState(KEYA, (snr*4+3), DefaultKey, SelectedSnr);    // 校驗1扇區密碼，密碼位於每一扇區第3塊
                                          // 驗證A密鑰，塊地址，扇區密碼，卡序列號
                    {
                        if(!status)
                        {
                            //讀寫卡
                            status = PcdRead((snr*4+0), buf);   // 讀卡，讀取1扇區0塊數據到buf[0]-buf[16]
//                          status = PcdWrite((snr*4+0), "way2");   // 寫卡，將buf[0]-buf[16]寫入1扇區0塊
                            if(!status) 
                            {
                                //讀寫成功
                                printf("read finish!\n");
                                printf("讀到的值是： %s\n",buf);
                                WaitCardOff();
                            }
                        }
                    }
                }
            }
        }
    }
}
 

RC522.h

#ifndef __RC522_H
#define __RC522_H

#define MF522_RST_PIN                    GPIO_Pin_11
#define MF522_RST_PORT                   GPIOB
#define MF522_RST_CLK                    RCC_APB2Periph_GPIOB

#define MF522_MISO_PIN                   GPIO_Pin_10
#define MF522_MISO_PORT                  GPIOB
#define MF522_MISO_CLK                   RCC_APB2Periph_GPIOB

#define MF522_MOSI_PIN                   GPIO_Pin_1
#define MF522_MOSI_PORT                  GPIOB
#define MF522_MOSI_CLK                   RCC_APB2Periph_GPIOB

#define MF522_SCK_PIN                    GPIO_Pin_0
#define MF522_SCK_PORT                   GPIOB
#define MF522_SCK_CLK                    RCC_APB2Periph_GPIOB

#define MF522_NSS_PIN                    GPIO_Pin_7
#define MF522_NSS_PORT                   GPIOA
#define MF522_NSS_CLK                    RCC_APB2Periph_GPIOA

#define RST_H                            GPIO_SetBits(MF522_RST_PORT, MF522_RST_PIN)
#define RST_L                            GPIO_ResetBits(MF522_RST_PORT, MF522_RST_PIN)
#define MOSI_H                           GPIO_SetBits(MF522_MOSI_PORT, MF522_MOSI_PIN)
#define MOSI_L                           GPIO_ResetBits(MF522_MOSI_PORT, MF522_MOSI_PIN)
#define SCK_H                            GPIO_SetBits(MF522_SCK_PORT, MF522_SCK_PIN)
#define SCK_L                            GPIO_ResetBits(MF522_SCK_PORT, MF522_SCK_PIN)
#define NSS_H                            GPIO_SetBits(MF522_NSS_PORT, MF522_NSS_PIN)
#define NSS_L                            GPIO_ResetBits(MF522_NSS_PORT, MF522_NSS_PIN)
#define READ_MISO                        GPIO_ReadInputDataBit(MF522_MISO_PORT, MF522_MISO_PIN)

// 函數原型
void PcdInit(void);
char PcdReset(void);
void PcdAntennaOn(void);
void PcdAntennaOff(void);
char PcdRequest(unsigned char req_code,unsigned char *pTagType);
char PcdAnticoll(unsigned char *pSnr);
char PcdSelect(unsigned char *pSnr);
char PcdAuthState(unsigned char auth_mode,unsigned char addr,unsigned char *pKey,unsigned char *pSnr);
char PcdRead(unsigned char addr,unsigned char *pData);
char PcdWrite(unsigned char addr,unsigned char *pData);
char PcdValue(unsigned char dd_mode,unsigned char addr,unsigned char *pValue);
char PcdBakValue(unsigned char sourceaddr, unsigned char goaladdr);
char PcdHalt(void);
char PcdComMF522(unsigned char Command,
                 unsigned char *pInData, 
                 unsigned char InLenByte,
                 unsigned char *pOutData, 
                 unsigned int  *pOutLenBit);
void CalulateCRC(unsigned char *pIndata,unsigned char len,unsigned char *pOutData);
void WriteRawRC(unsigned char Address,unsigned char value);
unsigned char ReadRawRC(unsigned char Address);
void SetBitMask(unsigned char reg,unsigned char mask);
void ClearBitMask(unsigned char reg,unsigned char mask);
char M500PcdConfigISOType(unsigned char type);
void delay_10ms(unsigned int _10ms);
void WaitCardOff(void);

// MF522命令字
#define PCD_IDLE              0x00               //取消當前命令
#define PCD_AUTHENT           0x0E               //驗證密鑰
#define PCD_RECEIVE           0x08               //接收數據
#define PCD_TRANSMIT          0x04               //發送數據
#define PCD_TRANSCEIVE        0x0C               //發送並接收數據
#define PCD_RESETPHASE        0x0F               //復位
#define PCD_CALCCRC           0x03               //CRC計算


// Mifare_One卡片命令字
#define PICC_REQIDL           0x26               //尋天線區內未進入休眠狀態
#define PICC_REQALL           0x52               //尋天線區內全部卡
#define PICC_ANTICOLL1        0x93               //防沖撞
#define PICC_ANTICOLL2        0x95               //防沖撞
#define PICC_AUTHENT1A        0x60               //驗證A密鑰
#define PICC_AUTHENT1B        0x61               //驗證B密鑰
#define PICC_READ             0x30               //讀塊
#define PICC_WRITE            0xA0               //寫塊
#define PICC_DECREMENT        0xC0               //扣款
#define PICC_INCREMENT        0xC1               //充值
#define PICC_RESTORE          0xC2               //調塊數據到緩沖區
#define PICC_TRANSFER         0xB0               //保存緩沖區中數據
#define PICC_HALT             0x50               //休眠

// MF522 FIFO長度定義
#define DEF_FIFO_LENGTH       64                 //FIFO size=64byte

// MF522寄存器定義
// PAGE 0
#define     RFU00                 0x00    
#define     CommandReg            0x01    
#define     ComIEnReg             0x02    
#define     DivlEnReg             0x03    
#define     ComIrqReg             0x04    
#define     DivIrqReg             0x05
#define     ErrorReg              0x06    
#define     Status1Reg            0x07    
#define     Status2Reg            0x08    
#define     FIFODataReg           0x09
#define     FIFOLevelReg          0x0A
#define     WaterLevelReg         0x0B
#define     ControlReg            0x0C
#define     BitFramingReg         0x0D
#define     CollReg               0x0E
#define     RFU0F                 0x0F
// PAGE 1     
#define     RFU10                 0x10
#define     ModeReg               0x11
#define     TxModeReg             0x12
#define     RxModeReg             0x13
#define     TxControlReg          0x14
#define     TxAutoReg             0x15
#define     TxSelReg              0x16
#define     RxSelReg              0x17
#define     RxThresholdReg        0x18
#define     DemodReg              0x19
#define     RFU1A                 0x1A
#define     RFU1B                 0x1B
#define     MifareReg             0x1C
#define     RFU1D                 0x1D
#define     RFU1E                 0x1E
#define     SerialSpeedReg        0x1F
// PAGE 2    
#define     RFU20                 0x20  
#define     CRCResultRegM         0x21
#define     CRCResultRegL         0x22
#define     RFU23                 0x23
#define     ModWidthReg           0x24
#define     RFU25                 0x25
#define     RFCfgReg              0x26
#define     GsNReg                0x27
#define     CWGsCfgReg            0x28
#define     ModGsCfgReg           0x29
#define     TModeReg              0x2A
#define     TPrescalerReg         0x2B
#define     TReloadRegH           0x2C
#define     TReloadRegL           0x2D
#define     TCounterValueRegH     0x2E
#define     TCounterValueRegL     0x2F
// PAGE 3      
#define     RFU30                 0x30
#define     TestSel1Reg           0x31
#define     TestSel2Reg           0x32
#define     TestPinEnReg          0x33
#define     TestPinValueReg       0x34
#define     TestBusReg            0x35
#define     AutoTestReg           0x36
#define     VersionReg            0x37
#define     AnalogTestReg         0x38
#define     TestDAC1Reg           0x39  
#define     TestDAC2Reg           0x3A   
#define     TestADCReg            0x3B   
#define     RFU3C                 0x3C   
#define     RFU3D                 0x3D   
#define     RFU3E                 0x3E   
#define     RFU3F                 0x3F


#define     REQ_ALL               0x52
#define     KEYA                  0x60

// 和MF522通訊時返回的錯誤代碼
#define MI_OK                          (char)0
#define MI_NOTAGERR                    (char)(-1)
#define MI_ERR                         (char)(-2)

#endif

RC522.c

#include "RC522.H"
#include "stm32f10x_gpio.h"

#define MAXRLEN 18                        

void PcdInit()
{
      GPIO_InitTypeDef  GPIO_InitStructure;

      /* Enable the GPIO Clock */
      RCC_APB2PeriphClockCmd(MF522_RST_CLK, ENABLE);

      /* Configure the GPIO pin */
      GPIO_InitStructure.GPIO_Pin = MF522_RST_PIN;
      GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
      GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;

      GPIO_Init(MF522_RST_PORT, &GPIO_InitStructure);

      /* Enable the GPIO Clock */
      RCC_APB2PeriphClockCmd(MF522_MISO_CLK, ENABLE);

      /* Configure the GPIO pin */
      GPIO_InitStructure.GPIO_Pin = MF522_MISO_PIN;
      GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
      GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;

      GPIO_Init(MF522_MISO_PORT, &GPIO_InitStructure);

      /* Enable the GPIO Clock */
      RCC_APB2PeriphClockCmd(MF522_MOSI_CLK, ENABLE);

      /* Configure the GPIO pin */
      GPIO_InitStructure.GPIO_Pin = MF522_MOSI_PIN;
      GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
      GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;

      GPIO_Init(MF522_MOSI_PORT, &GPIO_InitStructure);

      /* Enable the GPIO Clock */
      RCC_APB2PeriphClockCmd(MF522_SCK_CLK, ENABLE);

      /* Configure the GPIO pin */
      GPIO_InitStructure.GPIO_Pin = MF522_SCK_PIN;
      GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
      GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;

      GPIO_Init(MF522_SCK_PORT, &GPIO_InitStructure);

      /* Enable the GPIO Clock */
      RCC_APB2PeriphClockCmd(MF522_NSS_CLK, ENABLE);

      /* Configure the GPIO pin */
      GPIO_InitStructure.GPIO_Pin = MF522_NSS_PIN;
      GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
      GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;

      GPIO_Init(MF522_NSS_PORT, &GPIO_InitStructure);
}

//功    能：尋卡
//參數說明: req_code[IN]:尋卡方式
//                0x52 = 尋感應區內所有符合14443A標準的卡
//                0x26 = 尋未進入休眠狀態的卡
//                pTagType[OUT]：卡片類型代碼
//                0x4400 = Mifare_UltraLight
//                0x0400 = Mifare_One(S50)
//                0x0200 = Mifare_One(S70)
//                0x0800 = Mifare_Pro(X)
//                0x4403 = Mifare_DESFire
//返    回: 成功返回MI_OK
char PcdRequest(unsigned char req_code,unsigned char *pTagType)
{
   char status;  
   unsigned int  unLen;
   unsigned char ucComMF522Buf[MAXRLEN]; 
//  unsigned char xTest ;
   ClearBitMask(Status2Reg,0x08);
   WriteRawRC(BitFramingReg,0x07);

//  xTest = ReadRawRC(BitFramingReg);
//  if(xTest == 0x07 )
 //   { LED_GREEN  =0 ;}
 // else {LED_GREEN =1 ;while(1){}}
   SetBitMask(TxControlReg,0x03);
 
   ucComMF522Buf[0] = req_code;

   status = PcdComMF522(PCD_TRANSCEIVE,ucComMF522Buf,1,ucComMF522Buf,&unLen);
//     if(status  == MI_OK )
//   { LED_GREEN  =0 ;}
//   else {LED_GREEN =1 ;}
   if ((status == MI_OK) && (unLen == 0x10))
   {    
       *pTagType     = ucComMF522Buf[0];
       *(pTagType+1) = ucComMF522Buf[1];
   }
   else
   {   status = MI_ERR;   }
   
   return status;
}

//功    能：防沖撞
//參數說明: pSnr[OUT]:卡片序列號，4字節
//返    回: 成功返回MI_OK
char PcdAnticoll(unsigned char *pSnr)
{
    char status;
    unsigned char i,snr_check=0;
    unsigned int  unLen;
    unsigned char ucComMF522Buf[MAXRLEN]; 
    

    ClearBitMask(Status2Reg,0x08);
    WriteRawRC(BitFramingReg,0x00);
    ClearBitMask(CollReg,0x80);
 
    ucComMF522Buf[0] = PICC_ANTICOLL1;
    ucComMF522Buf[1] = 0x20;

    status = PcdComMF522(PCD_TRANSCEIVE,ucComMF522Buf,2,ucComMF522Buf,&unLen);

    if (status == MI_OK)
    {
         for (i=0; i<4; i++)
         {   
             *(pSnr+i)  = ucComMF522Buf[i];
             snr_check ^= ucComMF522Buf[i];
         }
         if (snr_check != ucComMF522Buf[i])
         {   status = MI_ERR;    }
    }
    
    SetBitMask(CollReg,0x80);
    return status;
}

//功    能：選定卡片
//參數說明: pSnr[IN]:卡片序列號，4字節
//返    回: 成功返回MI_OK
char PcdSelect(unsigned char *pSnr)
{
    char status;
    unsigned char i;
    unsigned int  unLen;
    unsigned char ucComMF522Buf[MAXRLEN]; 
    
    ucComMF522Buf[0] = PICC_ANTICOLL1;
    ucComMF522Buf[1] = 0x70;
    ucComMF522Buf[6] = 0;
    for (i=0; i<4; i++)
    {
        ucComMF522Buf[i+2] = *(pSnr+i);
        ucComMF522Buf[6]  ^= *(pSnr+i);
    }
    CalulateCRC(ucComMF522Buf,7,&ucComMF522Buf[7]);
  
    ClearBitMask(Status2Reg,0x08);

    status = PcdComMF522(PCD_TRANSCEIVE,ucComMF522Buf,9,ucComMF522Buf,&unLen);
    
    if ((status == MI_OK) && (unLen == 0x18))
    {   status = MI_OK;  }
    else
    {   status = MI_ERR;    }

    return status;
}

//功    能：驗證卡片密碼
//參數說明: auth_mode[IN]: 密碼驗證模式
//                 0x60 = 驗證A密鑰
//                 0x61 = 驗證B密鑰 
//          addr[IN]：塊地址
//          pKey[IN]：密碼
//          pSnr[IN]：卡片序列號，4字節
//返    回: 成功返回MI_OK       
char PcdAuthState(unsigned char auth_mode,unsigned char addr,unsigned char *pKey,unsigned char *pSnr)
{
    char status;
    unsigned int  unLen;
    unsigned char i,ucComMF522Buf[MAXRLEN]; 

    ucComMF522Buf[0] = auth_mode;
    ucComMF522Buf[1] = addr;
    for (i=0; i<6; i++)
    {    ucComMF522Buf[i+2] = *(pKey+i);   }
    for (i=0; i<6; i++)
    {    ucComMF522Buf[i+8] = *(pSnr+i);   }
 //   memcpy(&ucComMF522Buf[2], pKey, 6); 
 //   memcpy(&ucComMF522Buf[8], pSnr, 4); 
    
    status = PcdComMF522(PCD_AUTHENT,ucComMF522Buf,12,ucComMF522Buf,&unLen);
    if ((status != MI_OK) || (!(ReadRawRC(Status2Reg) & 0x08)))
    {   status = MI_ERR;   }
    
    return status;
}

//功    能：讀取M1卡一塊數據
//參數說明: addr[IN]：塊地址
//          pData[OUT]：讀出的數據，16字節
//返    回: 成功返回MI_OK
char PcdRead(unsigned char addr,unsigned char *pData)
{
    char status;
    unsigned int  unLen;
    unsigned char i,ucComMF522Buf[MAXRLEN]; 

    ucComMF522Buf[0] = PICC_READ;
    ucComMF522Buf[1] = addr;
    CalulateCRC(ucComMF522Buf,2,&ucComMF522Buf[2]);
   
    status = PcdComMF522(PCD_TRANSCEIVE,ucComMF522Buf,4,ucComMF522Buf,&unLen);
    if ((status == MI_OK) && (unLen == 0x90))
 //   {   memcpy(pData, ucComMF522Buf, 16);   }
    {
        for (i=0; i<16; i++)
        {    *(pData+i) = ucComMF522Buf[i];   }
    }
    else
    {   status = MI_ERR;   }
    
    return status;
}

//功    能：寫數據到M1卡一塊
//參數說明: addr[IN]：塊地址
//          pData[IN]：寫入的數據，16字節
//返    回: 成功返回MI_OK         
char PcdWrite(unsigned char addr,unsigned char *pData)
{
    char status;
    unsigned int  unLen;
    unsigned char i,ucComMF522Buf[MAXRLEN]; 
    
    ucComMF522Buf[0] = PICC_WRITE;
    ucComMF522Buf[1] = addr;
    CalulateCRC(ucComMF522Buf,2,&ucComMF522Buf[2]);
 
    status = PcdComMF522(PCD_TRANSCEIVE,ucComMF522Buf,4,ucComMF522Buf,&unLen);

    if ((status != MI_OK) || (unLen != 4) || ((ucComMF522Buf[0] & 0x0F) != 0x0A))
    {   status = MI_ERR;   }
        
    if (status == MI_OK)
    {
        //memcpy(ucComMF522Buf, pData, 16);

        for (i=0; i<16; i++)
        {    ucComMF522Buf[i] = *(pData+i);   }
        CalulateCRC(ucComMF522Buf,16,&ucComMF522Buf[16]);

        status = PcdComMF522(PCD_TRANSCEIVE,ucComMF522Buf,18,ucComMF522Buf,&unLen);
        if ((status != MI_OK) || (unLen != 4) || ((ucComMF522Buf[0] & 0x0F) != 0x0A))
        {   status = MI_ERR;   }
    }
    
    return status;
}

//功    能：命令卡片進入休眠狀態
//返    回: 成功返回MI_OK
char PcdHalt(void)
{
    unsigned int  unLen;
    unsigned char ucComMF522Buf[MAXRLEN]; 

    ucComMF522Buf[0] = PICC_HALT;
    ucComMF522Buf[1] = 0;
    CalulateCRC(ucComMF522Buf,2,&ucComMF522Buf[2]);
 
    PcdComMF522(PCD_TRANSCEIVE,ucComMF522Buf,4,ucComMF522Buf,&unLen);

    return MI_OK;
}

//用MF522計算CRC16函數
void CalulateCRC(unsigned char *pIndata,unsigned char len,unsigned char *pOutData)
{
    unsigned char i,n;
    ClearBitMask(DivIrqReg,0x04);
    WriteRawRC(CommandReg,PCD_IDLE);
    SetBitMask(FIFOLevelReg,0x80);
    for (i=0; i<len; i++)
    {   WriteRawRC(FIFODataReg, *(pIndata+i));   }
    WriteRawRC(CommandReg, PCD_CALCCRC);
    i = 0xFF;
    do 
    {
        n = ReadRawRC(DivIrqReg);
        i--;
    }
    while ((i!=0) && !(n&0x04));
    pOutData[0] = ReadRawRC(CRCResultRegL);
    pOutData[1] = ReadRawRC(CRCResultRegM);
}

//功    能：復位RC522
//返    回: 成功返回MI_OK
char PcdReset(void)
{
    RST_H;
    delay_10ms(1);
    RST_L;
    delay_10ms(1);
    RST_H;
      delay_10ms(10);
    
        if(ReadRawRC(0x02) == 0x80)
        {
        }

    WriteRawRC(CommandReg,PCD_RESETPHASE);
    
    WriteRawRC(ModeReg,0x3D);            //和Mifare卡通訊，CRC初始值0x6363
    WriteRawRC(TReloadRegL,30);           
    WriteRawRC(TReloadRegH,0);
    WriteRawRC(TModeReg,0x8D);
    WriteRawRC(TPrescalerReg,0x3E);
    WriteRawRC(TxAutoReg,0x40);     
    return MI_OK;
}

//設置RC632的工作方式 
char M500PcdConfigISOType(unsigned char type)
{
   if (type == ‘A‘)                     //ISO14443_A
   { 
       ClearBitMask(Status2Reg,0x08);

 /*     WriteRawRC(CommandReg,0x20);    //as default   
       WriteRawRC(ComIEnReg,0x80);     //as default
       WriteRawRC(DivlEnReg,0x0);      //as default
       WriteRawRC(ComIrqReg,0x04);     //as default
       WriteRawRC(DivIrqReg,0x0);      //as default
       WriteRawRC(Status2Reg,0x0);//80    //trun off temperature sensor
       WriteRawRC(WaterLevelReg,0x08); //as default
       WriteRawRC(ControlReg,0x20);    //as default
       WriteRawRC(CollReg,0x80);    //as default
*/
       WriteRawRC(ModeReg,0x3D);//3F
/*     WriteRawRC(TxModeReg,0x0);      //as default???
       WriteRawRC(RxModeReg,0x0);      //as default???
       WriteRawRC(TxControlReg,0x80);  //as default???

       WriteRawRC(TxSelReg,0x10);      //as default???
   */
       WriteRawRC(RxSelReg,0x86);//84
 //      WriteRawRC(RxThresholdReg,0x84);//as default
 //      WriteRawRC(DemodReg,0x4D);      //as default

 //      WriteRawRC(ModWidthReg,0x13);//26
       WriteRawRC(RFCfgReg,0x7F);   //4F
    /*   WriteRawRC(GsNReg,0x88);        //as default???
       WriteRawRC(CWGsCfgReg,0x20);    //as default???
       WriteRawRC(ModGsCfgReg,0x20);   //as default???
*/
       WriteRawRC(TReloadRegL,30);//tmoLength);// TReloadVal = ‘h6a =tmoLength(dec) 
       WriteRawRC(TReloadRegH,0);
       WriteRawRC(TModeReg,0x8D);
       WriteRawRC(TPrescalerReg,0x3E);
       

  //     PcdSetTmo(106);
       delay_10ms(1);
       PcdAntennaOn();
   }
   else{ return (char)-1; }
   
   return MI_OK;
}

//功    能：讀RC632寄存器
//參數說明：Address[IN]:寄存器地址
//返    回：讀出的值
unsigned char ReadRawRC(unsigned char Address)
{
     unsigned char i, ucAddr;
     unsigned char ucResult=0;

     NSS_L;
     ucAddr = ((Address<<1)&0x7E)|0x80;

     for(i=8;i>0;i--)
     {
         SCK_L;
         if(ucAddr&0x80)
            MOSI_H;
         else
                 MOSI_L;
         SCK_H;
         ucAddr <<= 1;
     }

     for(i=8;i>0;i--)
     {
         SCK_L;
         ucResult <<= 1;
         SCK_H;
         if(READ_MISO == 1)
            ucResult |= 1;
     }

     NSS_H;
     SCK_H;
     return ucResult;
}

//功    能：寫RC632寄存器
//參數說明：Address[IN]:寄存器地址
//          value[IN]:寫入的值
void WriteRawRC(unsigned char Address, unsigned char value)
{  
    unsigned char i, ucAddr;

    SCK_L;
    NSS_L;
    ucAddr = ((Address<<1)&0x7E);

    for(i=8;i>0;i--)
    {
        if(ucAddr&0x80)
            MOSI_H;
        else
            MOSI_L;
        SCK_H;
        ucAddr <<= 1;
        SCK_L;
    }

    for(i=8;i>0;i--)
    {
        if(value&0x80)
            MOSI_H;
        else
            MOSI_L;
        SCK_H;
        value <<= 1;
        SCK_L;
    }
    NSS_H;
    SCK_H;
}

//功    能：置RC522寄存器位
//參數說明：reg[IN]:寄存器地址
//          mask[IN]:置位值
void SetBitMask(unsigned char reg,unsigned char mask)  
{
    char tmp = 0x0;
    tmp = ReadRawRC(reg);
    WriteRawRC(reg,tmp | mask);  // set bit mask
}

//功    能：清RC522寄存器位
//參數說明：reg[IN]:寄存器地址
//          mask[IN]:清位值
void ClearBitMask(unsigned char reg,unsigned char mask)  
{
    char tmp = 0x0;
    tmp = ReadRawRC(reg);
    WriteRawRC(reg, tmp & ~mask);  // clear bit mask
} 

//功    能：通過RC522和ISO14443卡通訊
//參數說明：Command[IN]:RC522命令字
//          pInData[IN]:通過RC522發送到卡片的數據
//          InLenByte[IN]:發送數據的字節長度
//          pOutData[OUT]:接收到的卡片返回數據
//          *pOutLenBit[OUT]:返回數據的位長度
char PcdComMF522(unsigned char Command, 
                 unsigned char *pInData, 
                 unsigned char InLenByte,
                 unsigned char *pOutData, 
                 unsigned int  *pOutLenBit)
{
    char status = MI_ERR;
    unsigned char irqEn   = 0x00;
    unsigned char waitFor = 0x00;
    unsigned char lastBits;
    unsigned char n;
    unsigned int i;
    switch (Command)
    {
       case PCD_AUTHENT:
          irqEn   = 0x12;
          waitFor = 0x10;
          break;
       case PCD_TRANSCEIVE:
          irqEn   = 0x77;
          waitFor = 0x30;
          break;
       default:
         break;
    }
   
    WriteRawRC(ComIEnReg,irqEn|0x80);
    ClearBitMask(ComIrqReg,0x80);
    WriteRawRC(CommandReg,PCD_IDLE);
    SetBitMask(FIFOLevelReg,0x80);
    
    for (i=0; i<InLenByte; i++)
    {   WriteRawRC(FIFODataReg, pInData[i]);    }
    WriteRawRC(CommandReg, Command);
   
    
    if (Command == PCD_TRANSCEIVE)
    {    SetBitMask(BitFramingReg,0x80);  }
    
//    i = 600;//根據時鐘頻率調整，操作M1卡最大等待時間25ms
 i = 2000;
    do 
    {
         n = ReadRawRC(ComIrqReg);
         i--;
    }
    while ((i!=0) && !(n&0x01) && !(n&waitFor));
    ClearBitMask(BitFramingReg,0x80);
          
    if (i!=0)
    {    
         if(!(ReadRawRC(ErrorReg)&0x1B))
         {
             status = MI_OK;
             if (n & irqEn & 0x01)
             {   status = MI_NOTAGERR;   }
             if (Command == PCD_TRANSCEIVE)
             {
                n = ReadRawRC(FIFOLevelReg);
                lastBits = ReadRawRC(ControlReg) & 0x07;
                if (lastBits)
                {   *pOutLenBit = (n-1)*8 + lastBits;   }
                else
                {   *pOutLenBit = n*8;   }
                if (n == 0)
                {   n = 1;    }
                if (n > MAXRLEN)
                {   n = MAXRLEN;   }
                for (i=0; i<n; i++)
                {   pOutData[i] = ReadRawRC(FIFODataReg);    }
            }
         }
         else
         {   status = MI_ERR;   }
        
   }
   

   SetBitMask(ControlReg,0x80);           // stop timer now
   WriteRawRC(CommandReg,PCD_IDLE); 
   return status;
}

//開啟天線  
//每次啟動或關閉天險發射之間應至少有1ms的間隔
void PcdAntennaOn()
{
    unsigned char i;
    i = ReadRawRC(TxControlReg);
    if (!(i & 0x03))
    {
        SetBitMask(TxControlReg, 0x03);
    }
}

//關閉天線
void PcdAntennaOff()
{
    ClearBitMask(TxControlReg, 0x03);
}

//等待卡離開
void WaitCardOff(void)
{
    char          status;
  unsigned char TagType[2];

    while(1)
    {
        status = PcdRequest(REQ_ALL, TagType);
        if(status)
        {
            status = PcdRequest(REQ_ALL, TagType);
            if(status)
            {
                status = PcdRequest(REQ_ALL, TagType);
                if(status)
                {
                    return;
                }
            }
        }
        delay_10ms(10);
    }
}

// Delay 10ms
void delay_10ms(unsigned int _10ms)
{
    unsigned int i, j;

    for(i=0; i<_10ms; i++)
    {
        for(j=0; j<60000; j++);
    }
}

基於Stm32的RFID-RC522模塊的對RFID讀寫使用