sd_rw2.lst

PIC18读取sd卡的程序

     1: //**************************************************
     2: // 项目：PIC单片机对SD卡进行单块数据的读写操作
     3: // 系统：PIC18F877A, 16MHz,   SPI(主)
     4: // 编程：2005-12
     5: //**************************************************
     6: 
     7: #include <pic18.h>
     8: //  __CONFIG (HS & PROTECT & PWRTEN & BOREN & WDTDIS);
     9: #define  SD_TEST
    10: 
    11: void  crcInit(void);
    12: unsigned int crcCompute(unsigned char * message, unsigned int nBytes);
    13: 
    14: 
    15: #define  CMD0     0x00                    //GO IDLE STATE
    16: #define  CMD1     0x01                    //SEND OP COND
    17: #define  CMD9     0x09                    //SEND CSD
    18: #define  CMD13    0x0d                    //SEND STATUS
    19: #define  CMD16    0x10                    //SET BLOCK LENGTH
    20: #define  CMD17    0x11                    //READ SINGLE BLOCK
    21: #define  CMD24    0x18                    //WRITE BLOCK
    22: #define  CMD59    0x3B                    //CRC_ON_OFF
    23: 
    24: #define  W_ADDR   0x00000001                  //写地址
    25: #define  R_ADDR   0x00000001                  //读地址
    26: #define  BLOCKlEN    0x000a               //设置读写块的长度为10，默认的块长度在CSD中
    27: 
    28: #define  SPICtrl   RB0                     //SPI片选,待定
    29: #define  H_FF      0xff                    //发送FF，MISO模式
    30: #define  NOARG    0x00000000               //命令无参数
    31: #define  C_R1     1                        //响应字节数1
    32: #define  C_R1b    2                        //响应字节数1,有busy信号，写操作
    33: #define  NSAC     8                                                     //在CSD中设定
    34: #define BL_LEN    12
    35: 
    36: #define FD_FE    0xfe                    //发送首字节为0xFE
    37: //开辟两个缓冲区，大小均为一个块地址的大小，对发送缓冲区的前十个数据赋初值
    38: 
    39: unsigned char  w_buf[BL_LEN-2]={0Xfe,1,2,3,4,5,6,7,8,9};    //发送缓冲区
    40: unsigned char  r_buf[BL_LEN];           //接受缓冲区，不包括CRC校验值
    41: unsigned int   *wr_crc;     //缓冲区CRC值存放区
    42: unsigned char  * WB_re ;             //接收写数据块的响应
    43: 
    44: unsigned char  SW_rst[6]  =  {0x40,0x0,0x0,0x0,0x0,0x95};   //软件复位命令
    45: 
    46: #ifdef SD_TEST
    47: unsigned char  csd[16] ;            //存放CSD寄存器的信息
    48: /***************************************************************************/
    49: //         CSD 128bit register      P64 definition
    50: //         [119:112] TAAC           
    51: //         [83:80] READ_BL_LEN    [79] READ_BL_PARTIAL   (allways = 1 in SD Memory Card)最小数据块可为1Byte
    52: //         [25:22] WRITE_BL_LEN   [21] WRIE_BL_PARTIAL    [7:1] CRC
    53: /***************************************************************************/
    54: #endif
    55: 
    56: bit   b_sdw;                        //写操作完成标志位
    57: bit   b_sdr;                        //读操作完成标志位
    58: bit   b_cmdnr;                      //命令无响应标志位
    59: bit   b_dnr;                        //数据接收无响应标志位
    60: bit       b_cmdr_er;                                    //命令响应错误标志位
    61: 
    62: 
    63: //系统初始化
    64:  void Sys_Init(void) 
    65:    {   
    66:         
    67:    SSPSTAT=0 ;         //SMP=0,CKE=0,BF=0
    68:    SSPCON1=0b00100010; //SSPEN=1,CKP=0,FOSC/64
    69: 
    70:    TRISB=0b11111100; //RB0,RB1输出
    71:    TRISC=0b10010111; //RC3,5,6输出
    72:    RBPU=1;           //RB弱上拉关闭
    73:         
    74:    b_sdw=0;                        //写操作完成标志位
    75:    b_sdr=0;                        //读操作完成标志位
    76:    b_cmdnr=0;                      //命令无响应标志
    77:    b_dnr=0;
    78:    WB_re = 0x00;                    //清空寄存器
    79:    wr_crc = 0x0000;
    80:  
    81:    }
    82: 
    83:    //中断初始化
    84:    void Int_Init(void) 
    85:    {
    86:       //SPI中断
    87:        SSPIF=0;         //清除SPI中断标志
    88:        SSPIE=1;         //中断允许？采用查询方式  
    89: 
    90:       //总中断
    91:        PEIE=0;          //外围中断禁止
    92:        GIE=0;           //总中断禁止
    93:    }
    94:    
    95:   /************************************************************/
    96:   /*   PIC发送数据
    97:   /************************************************************/
    98:    void PIC_W ( char * w_ad , int nByte)        //PIC发送，首地址，字节数
    99:    {
   100:       unsigned char * w_ptr;
   101:       unsigned int i;
   102:       w_ptr = w_ad;
   103:       for ( i = 0; i < nByte; i++ )
   104:       {
   105:             SSPBUF = * w_ptr;
   106:             while (!SSPIF) {;}
   107:             SSPIF = 0;
   108:             w_ptr ++;
   109:       }
   110: 
   111:    }
   112:    
   113:    /************************************************************/
   114:   /*   PIC接收数据
   115:   /************************************************************/
   116:    void PIC_R ( char * r_ad , int nByte)        //PIC接收，首地址，字节数
   117:    {
   118:       unsigned char * r_ptr;
   119:       unsigned int i;
   120:       r_ptr = r_ad;
   121:       for ( i = 0; i < nByte; i++ )
   122:       {
   123:             SSPBUF = H_FF ;
   124:             while (!SSPIF) {;}
   125:             SSPIF = 0;
   126:             * r_ptr = SSPBUF;
   127:             r_ptr ++;
   128:       }
   129: 
   130:    }
   131:   
   132:    /*****************************************************************/
   133:    //In the non-protected mode   the CRC bits of the command,
   134:    //response and data tokens are still required in the tokens.
   135:    // However, they are defined as ‘don’t care’ for the transmitter
   136:    // and ignored by the receiver
   137:    /*****************************************************************/
   138:    unsigned char CMD_CRC(char * cmdcrc)
   139:         {
   140:       unsigned char crc7;
   141:       unsigned int crc_res;                   //存放crc计算结果
   142:       crc_res = crcCompute( cmdcrc, 5);          //计算结果为16bit
   143:     ////////////////////////                             //如何取期中的一个字节作为返回值
   144:           crc7 = (char)(crc_res>>8 &0xff | 0x01);
   145:           return crc7;
   146:    }
   147:    
   148:   /************************************************************/
   149:   /*   等待周期,表示等待周期
   150:   /************************************************************/
   151:   void SPI_wt(int n)                       //SD卡准备好
   152:       {
   153:          char * busy;
   154:          unsigned i;
   155:          PIC_R (busy,i);
   156:       }
   157:   
   158:   
   159:   /************************************************************/
   160:   /*   发送命令字
   161:   /************************************************************/
   162: 
   163:    struct COM1                               //命令控制结构
   164:    {
   165:      char c;
   166:      unsigned long l;
   167:      char e;
   168:    };
   169: 
   170:    union COM2
   171:    {
   172:       struct COM1 c6;
   173:       char c1[6];
   174:    };
   175: 
   176:    void SD_CMD ( char CMD,  unsigned long ARG )        //发送命令控制,响应类型为R1
   177:    {
   178:       char c_crc;
   179:       char * cmd_r1;
   180:       unsigned int tncr;
   181:       union COM2 command;
   182:       command.c6.c = 0x40 | CMD;
   183:       command.c6.l = ARG;
   184:       c_crc = CMD_CRC(command.c1);             //命令字节的首地址
   185:       command.c6.e = c_crc;
   186:       tncr = 0;
   187:       b_cmdnr = 0;                            //发送前对标志位进行初始化
   188:       b_cmdr_er = 0;
   189:       PIC_W( command.c1 , 6 );                 //send cmd 
   190: 
   191:       while(1)
   192:       {  
   193:          PIC_R ( cmd_r1 , 1); 
   194:          if( * cmd_r1 != 0xff )
   195:           {   break; }
   196:          else