这是我自己搜改的 希望大家多提建议 #include "HAL.H" //============================================================ //往SD卡定一字节 void SdWrite(unsigned char n) { unsigned char i; for(i=8;i;i--) { SD_CLK=0; SD_DI=(n&0x80); n<<=1; SD_CLK=1; } SD_DI=1; } //================================================================ //从SD卡读一字节 unsigned char SdRead() { unsigned char n,i; for(i=8;i;i--) { SD_CLK=0; SD_CLK=1; n<<=1; if(SD_DO) n|=1; } return n; } //================================================================ //读SD卡响应 unsigned char SdResponse() { unsigned char i=0,response; while(i<=8) { response=SdRead(); if(response==0x00) break; if(response==0x01) break; i++; } return response; } //================================================================ void SdCommand(unsigned char command, unsigned long argument, unsigned char CRC) { SdWrite(command|0x40); SdWrite(((unsigned char *)&argument)[0]); SdWrite(((unsigned char *)&argument)[1]); SdWrite(((unsigned char *)&argument)[2]); SdWrite(((unsigned char *)&argument)[3]); SdWrite(CRC); } //================================================================ unsigned char SdInit(void) { int delay=0, trials=0; unsigned char i; unsigned char response=0x01; //你这里定义response=0x01是不是多余啊 SD_CS=1; for(i=0;i<=9;i++) SdWrite(0xff); SD_CS=0; //Send Command 0 to put MMC in SPI mode SdCommand(0x00,0,0x95); //send CMD0 response=SdResponse(); if(response!=0x01) { return 0; } while(response==0x01) { SD_CS=1; SdWrite(0xff); SD_CS=0; SdCommand(0x01,0x00ffc000,0xff); // send CMD1 这里一定要写0x00ffc000吗？ response=SdResponse(); } SD_CS=1; SdWrite(0xff); return 1; } //================================================================ unsigned char SdWriteBlock(unsigned char *Block, unsigned long address) { unsigned char count; unsigned char dataResp; //Block size is 512 bytes exactly //First Lower SS SD_CS=0; //Then send write command SdCommand(0x18,address,0xff); //CMD24 WRITE_BLOCK if(SdResponse()==00) { SdWrite(0xff); SdWrite(0xff); SdWrite(0xff); //command was a success - now send data //start with DATA TOKEN = 0xFE SdWrite(0xfe); //now send data for(count=0;count<128;count++) { SdWrite(*Block++); SdWrite(*Block++); SdWrite(*Block++); SdWrite(*Block++); } //data block sent - now send checksum SdWrite(0xff); SdWrite(0xff); //Now read in the DATA RESPONSE token dataResp=SdRead(); //Following the DATA RESPONSE token //are a number of BUSY bytes //a zero byte indicates the MMC is busy while(SdRead()==0); dataResp=dataResp&0x0f; //mask the high byte of the DATA RESPONSE token SD_CS=1; SdWrite(0xff); if(dataResp==0x0b) { //printf("DATA WAS NOT ACCEPTED BY CARD -- CRC ERROR\n"); return 0; } if(dataResp==0x05) return 1; //printf("Invalid data Response token.\n"); return 0; } //printf("Command 0x18 (Write) was not received by the MMC.\n"); return 0; } //======================================================================= unsigned char SdReadBlock(unsigned char *Block, unsigned long address) { unsigned char count; //Block size is 512 bytes exactly //First Lower SS // printf("MMC_read_block\n"); SD_CS=0; //Then send read command SdCommand(0x11,address,0xff); //send CMD17 READ_SINGLE_BLOCK if(SdResponse()==00) { //command was a success - now send data //start with DATA TOKEN = 0xFE while(SdRead()!=0xfe); for(count=0;count<128;count++) { *Block++=SdRead(); *Block++=SdRead(); *Block++=SdRead(); *Block++=SdRead(); } //data block sent - now send checksum SdRead(); SdRead(); //send two CRC bytes to host //Now read in the DATA RESPONSE token SD_CS=1; SdRead(); return 1; } // printf("Command 0x11 (Read) was not received by the MMC.\n"); return 0; }
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