STM32 SD card_no file system added

The picture below shows the SD card part of the Wanli board

SD_PWR is connected to PD10 through a control

P-Channel 2.5-V (GS) MOSFET controls the power supply of the SD card

=====================================================================

SPI mode read and write SD card

SD card initialization process:

1. Initialize the SPI interface of STM32 to use low-speed mode
2. Delay at least 74clock
3. Send CMD0, need to return 0x01, enter the Idle state
4. Loop and send CMD55+ACMD41 until it returns 0x00, enter the Ready state
5. Set the read and write block size to 512byte 
5. Set the SPI of STM32 to high-speed mode



The process of reading a block

1. Send CMD17 (single block) or CMD18 (multiple blocks) read command, return 0x00
2. Receive data start token 0xfe + formal data 512Bytes + CRC check 2Bytes

The process of writing a block

1. Send CMD24 (single block) or CMD25 (multiple blocks) write command, return 0x00
2. Send data start token 0xfe + formal data 512Bytes + CRC check 2Bytes

/*******************************************************************************
* Function Name : SD_MMC_SPI_Init
* Description    : SD_MMC_SPI_Init
* Input          : None
* Output         : None
* Return         : zero init success, non-zero init error
*******************************************************************************/
u8 SD_MMC_SPI_Init(void)
{
GPIO_InitTypeDef GPIO_InitStructure;

/* Enable SPI1 and GPIO clocks */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1 | RCC_APB2Periph_GPIOA |
RCC_APB2Periph_SD_MMC_SPI_CS, ENABLE);

/* Configure SPI1 pins: SCK, MISO and MOSI */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5 | GPIO_Pin_6 | GPIO_Pin_7;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);

/* Configure SD_MMC_SPI_CS */
GPIO_InitStructure.GPIO_Pin = SD_MMC_SPI_CS_Pin_CS;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_Init(SD_MMC_SPI_CS, &GPIO_InitStructure);

//////////////////////////////////////////////////////////////////////////////
/* initialize SPI with lowest frequency */
SD_MMC_Low_Speed();

/* card needs 74 cycles minimum to start up */
for(u8 i = 0; i < 10; ++i)
{
/* wait 8 clock cycles */
SD_MMC_ReadWrite_Byte(0x00);
}

    /* address card */
SD_MMC_SPI_SELECT();

    /* reset card */
u8 response;
for(u16 i = 0; ; ++i)
{
response = SD_MMC_Send_Command(CMD_GO_IDLE_STATE , 0 );
if( response == 0x01 )
break;

        if(i == 0x1ff)
{
SD_MMC_SPI_DESELECT();
return 1;
}
}

/* wait for card to get ready */
for(u16 i = 0; ; ++i)
{
response = SD_MMC_Send_Command(CMD_SEND_OP_COND, 0);
if(!(response & (1 << R1_IDLE_STATE)))
break;

        if(i == 0x7fff)
{
SD_MMC_SPI_DESELECT();
return 1;
}
}

    /* set block size to 512 bytes */
if(SD_MMC_Send_Command(CMD_SET_BLOCKLEN, 512))
{
SD_MMC_SPI_DESELECT();
return 1;
}

    /* deaddress card */
SD_MMC_SPI_DESELECT();

    /* switch to highest SPI frequency possible */
SD_MMC_High_Speed();

return 0;
//////////////////////////////////////////////////////////////////////////////
}
 

/*******************************************************************************
* Function Name : SD_MMC_Read_Single_Block
* Description    : SD_MMC_Read_Single_Block
* Input          : sector number and buffer data point
* Output         : None
* Return         : zero success, non-zero error
*******************************************************************************/
u8 SD_MMC_Read_Single_Block(u32 sector, u8* buffer)
{
u8 Response;
u16 i;
u16 Retry = 0;

         //读命令 send read command
Response = SD_MMC_Send_Command(CMD_READ_SINGLE_BLOCK, sector<<9);

        if(Response != 0x00)
return Response;

        SD_MMC_SPI_SELECT();

        // start byte 0xfe
while(SD_MMC_ReadWrite_Byte(0xff) != 0xfe)
{
if(++Retry > 0xfffe)
{
SD_MMC_SPI_DESELECT();
return 1; //timeout
}
}

        for(i = 0; i < 512; ++i)
{
//Read 512 data
*buffer++ = SD_MMC_ReadWrite_Byte(0xff);
}

        SD_MMC_ReadWrite_Byte(0xff); //伪crc
SD_MMC_ReadWrite_Byte(0xff); //伪crc

        SD_MMC_SPI_DESELECT();
SD_MMC_ReadWrite_Byte(0xff); // extra 8 CLK

        return 0;
}

/*******************************************************************************
* Function Name : SD_MMC_Write_Single_Block
* Description    : SD_MMC_Write_Single_Block
* Input          : sector number and buffer data point
* Output         : None
* Return         : zero success, non-zero error.
*******************************************************************************/
u8 SD_MMC_Write_Single_Block(u32 sector, u8* buffer)
{
u8 Response;
u16 i;
u16 retry=0;

//写命令 send write command
Response = SD_MMC_Send_Command(CMD_WRITE_SINGLE_BLOCK, sector<<9);
if(Response != 0x00)
return Response;

SD_MMC_SPI_SELECT();

SD_MMC_ReadWrite_Byte(0xff);
SD_MMC_ReadWrite_Byte(0xff);
SD_MMC_ReadWrite_Byte(0xff);

        //发开始符 start byte 0xfe
SD_MMC_ReadWrite_Byte(0xfe);

//送512字节数据 send 512 bytes data
for(i=0; i<512; i++)
{
SD_MMC_ReadWrite_Byte(*buffer++);
}

SD_MMC_ReadWrite_Byte(0xff); //dummy crc
SD_MMC_ReadWrite_Byte(0xff); //dummy crc

Response = SD_MMC_ReadWrite_Byte(0xff);

//等待是否成功 judge if it successful
if( (Response&0x1f) != 0x05)
{
SD_MMC_SPI_DESELECT();
return Response;
}
//等待操作完 wait no busy
while(SD_MMC_ReadWrite_Byte(0xff) != 0x00)
{
if(retry++ > 0xfffe)
{
SD_MMC_SPI_DESELECT();
return 1;
}
}
SD_MMC_SPI_DESELECT();
SD_MMC_ReadWrite_Byte(0xff);// extra 8 CLK

return 0;
}

if( SD_MMC_SPI_Init() ==1)
printf(" _SD_MMC Initialization ERROR\r\n");
else
{
printf(" _SD_MMC Initialization OK\r\n");
//memset(buffer,0,512);
//Read the contents of a sector. Here, sector 0 is read.
SD_MMC_Read_Single_Block( 0 , buffer );
Uart1_PutString( buffer , 512 );
}