SD卡SPI模式读写驱动程序

/*SD卡SPI模式驱动实现文件*/ #include "SD_Drv.h" /*延时函数*/ void Delay_100us(void) { unsigned int i=8; while(i--) *P_Watchdog_Clear=0x0001; } //IOB口初始化函数 CS,DO,CLK设置为高电平输出 DI设置为无唤醒的悬浮输入 void SPI_IO_Init(void) { unsigned int tmp; tmp=*P_IOB_Dir; tmp |= (SPI_CS+SPI_DOUT+SPI_CLK); tmp&=~SPI_DIN; *P_IOB_Dir=tmp; tmp=*P_IOB_Attrib; tmp|=(SPI_CS+SPI_DOUT+SPI_CLK+SPI_DIN); *P_IOB_Attrib=tmp; tmp=*P_IOB_Data; tmp|=(SPI_CS+SPI_DOUT+SPI_CLK+SPI_DIN); *P_IOB_Data=tmp; } /*向SD卡发送一个字节的数据*/ void SPI_Send_Byte(unsigned char Data) { unsigned int nCount; unsigned char Buffer; Buffer=Data; for(nCount=0;nCount<8;nCount++) { SPI_CLK_RESET(); //CLK置低以备产生上升沿 if(Buffer&0x80) //待发数据为1 SPI_DOUT_SET(); //DO输出高电平 else //否则 SPI_DOUT_RESET(); //D0输出低电平 SPI_CLK_SET(); //产生时钟上升沿 Buffer=Buffer<<1; // CLK置高 } } /*从SD卡读取一个字节的数据*/ unsigned char SPI_Get_Byte(void) { unsigned char echo; unsigned int nCount; echo=0; for(nCount=0;nCount<8;nCount++) { echo=echo<<1; SPI_CLK_RESET(); //CLK置低以备产生上升沿 SPI_CLK_SET(); //CLK置高产生上升沿，读取数据 if(*P_IOB_Data & SPI_DIN) echo|=0x01; else echo&=0xfe; *P_Watchdog_Clear = 1; } return echo; } /*向SD卡发送命令*/ unsigned char SPI_Send_Cmd(unsigned char *Cmd) { unsigned char tmp; unsigned char retry=0; unsigned char i; SPI_CS_SET(); //禁止SD卡 SPI_Send_Byte(0xff); SPI_CS_RESET(); //使SD卡使能 for (i=0;i<6;i++) { SPI_Send_Byte(*Cmd++); } //获得8位的回应 SPI_Get_Byte(); do { //读取响应 tmp = SPI_Get_Byte(); retry++; } while((tmp==0xff)&&(retry<100)); return(tmp); } /*SD卡初始化程序*/ unsigned char SPI_Init(void) { unsigned char retry,temp; unsigned char i; //unsigned Init_Flag; unsigned char CMD[] = {0x40,0x00,0x00,0x00,0x00,0x95}; SPI_IO_Init(); //初始化驱动端口 Delay_100us(); for (i=0;i<16;i++) { SPI_Send_Byte(0xff); //发送至少74个时钟信号 } SPI_CS_RESET(); //使SD卡使能 //向SD卡发送CMD0 retry=0; do { //为了能够成功写入CMD0,在这里写200次 temp=SPI_Send_Cmd(CMD); retry++; if(retry==200) { //超过200次 return(INIT_CMD0_ERROR);//CMD0 Error! } } while(temp!=1); //回应01h，停止写入 //发送CMD1到SD卡 CMD[0] = 0x41; //CMD1 CMD[5] = 0xFF; retry=0; do { //为了能成功写入CMD1,写100次 temp=SPI_Send_Cmd(CMD); retry++; if(retry==100) { //超过100次 return(INIT_CMD1_ERROR);//CMD1 Error! } } while(temp!=0);//回应00h停止写入 SPI_CS_SET(); //使SD卡片选无效 return(INIT_SUCCESSED); //初始化成功 } //-------------------------------------------------------------------------------------------- //-------------------------------------------------------------------------------------------- unsigned char SD_write_sector(unsigned long addr,unsigned char *Buffer) { unsigned char tmp,retry; unsigned int i; //命令24 unsigned char CMD[] = {0x58,0x00,0x00,0x00,0x00,0xFF}; addr = addr << 9; //addr = addr * 512 CMD[1] = ((addr & 0xFF000000) >>24 ); CMD[2] = ((addr & 0x00FF0000) >>16 ); CMD[3] = ((addr & 0x0000FF00) >>8 ); //写命令24到SD卡中去 retry=0; do { //为了可靠写入，写100次 tmp=SPI_Send_Cmd(CMD); retry++; if(retry==100) { return(tmp); //send commamd Error! } } while(tmp!=0); //在写之前先产生100个时钟信号 for (i=0;i<100;i++) { SPI_Get_Byte(); } //写入开始字节 SPI_Send_Byte(0xFE); //现在可以写入512个字节 for (i=0;i<512;i++) { SPI_Send_Byte(*Buffer++); } //CRC-Byte SPI_Send_Byte(0xFF); //Dummy CRC SPI_Send_Byte(0xFF); //CRC Code tmp=SPI_Get_Byte(); // read response if((tmp & 0x1F)!=0x05) // 写入的512个字节是未被接受 { // SPI_CS_SET(); *P_IOB_Data|=SPI_CS; return(WRITE_BLOCK_ERROR); //Error! } //等到SD卡不忙为止 //因为数据被接受后，SD卡在向储存阵列中编程数据 while (SPI_Get_Byte()!=0xff){}; //禁止SD卡 // SPI_CS_SET(); *P_IOB_Data|=SPI_CS; return(0);//写入成功 } //---------------------------------------------------------------------------- // 获取数据到buffer中 //---------------------------------------------------------------------------- void SD_get_data(unsigned int Bytes,unsigned char *buffer) { unsigned int j; for (j=0;j<Bytes;j++) *buffer++ = SPI_Get_Byte(); } //------------------------------- //读一个扇区 //------------------------------------- unsigned char SD_Read_Sector(unsigned long sector,unsigned char *buffer) { unsigned char retry; //命令16 unsigned char CMD[] = {0x51,0x00,0x00,0x00,0x00,0xFF}; unsigned char temp; //地址变换 由逻辑块地址转为字节地址 sector = sector << 9; //sector = sector * 512 CMD[1] = ((sector & 0xFF000000) >>24 ); CMD[2] = ((sector & 0x00FF0000) >>16 ); CMD[3] = ((sector & 0x0000FF00) >>8 ); //将命令16写入SD卡 retry=0; do { //为了保证写入命令 一共写100次 temp=SPI_Send_Cmd(CMD); retry++; if(retry==100) { return(READ_BLOCK_ERROR); //block write Error! } } while(temp!=0); while (SPI_Get_Byte() != 0xfe); readPos=0; SD_get_data(512,buffer) ; //512字节被读出到buffer中 return 0; }