Electrical – SD card single write block

microcontrollersdcard

I'm presently writing the code for SAMD20 micro-controller and SDCard. I'v successfully written code for single block read and multi block successfully. I'm testing my code with San-disk 16 GB SDCard with HC-1 specs.

I'm stuck with writing the code for single block write.

I've followed following process:

Sent CMD24 command (with sector number 2001:just after first block of FAT32 FS )
Based on response started writing buffer with incremental data (0x00,0x01,0x02,0x03……..) (After Sending data token 0xfe)
Now after this, I'm waiting for data response (i.e. 0x05 for successful data write), which i didn't get. MISO line goes BUSY (0x00) after that and after some time, transit to high (0xff).

If I send CMD13 (arg=0x00) after this, I should get card status, but It is returning back with 0xC1 0x3F.

After reset, if I tried to read sector no. 2001. I get following results

WinHex screenshot

I think this is the correct procedure for SD Card write.

Any help will be appreciated.Thanks in advance.

Best Answer

As far as I'm aware, the correct procedure for a single-block write operation is:

Send CMD24
Wait for the 0x00 acknowledgement
Send 0xFE
Send entire block (512 bytes for modern cards)
Send 2-bytes of anything (or 2-byte CRC, if enabled)
Wait for xxx0yyy1 data response token
Check that yyy = 010

I have a suspicion that you're not waiting for the CMD24 acknowledgement before sending the data. That's what I did at first, too.

By the way, that output of sector 2001 looks suspiciously like a FAT FS Information Sector (which always starts with RRaA), which usually is located at block 1 of the partition. Does your partition start at sector 2000?

Related Solutions

Electronic – FatFs: Why am I not able to properly read sector 0

Turns out the answer had to do with the way I was implementing the SPI transactions using the Nordic SDK.

My rcvr_mmc function looked like this:

static
void rcvr_mmc (
    BYTE *buff, /* Pointer to read buffer */
    UINT bc     /* Number of bytes to receive */
)
{
    nrf_drv_spi_transfer(&spi, NULL, 0, buff, bc);
}

I assumed my rcvr_mmc was working since I was correctly parsing command responses. However, sector reads weren't working at all. I didn't even see a full 512*8 clock cycles.

Once I realized that was happened, I looked more closely at the Nordic SDK SPI driver and discovered this:

https://devzone.nordicsemi.com/question/66434/nrf_drv_spi_transfer-larger-transfer-size/

Since sector reads pass bc=512, this resulted in nothing really being read. My very inefficient hack for now to get this work is:

int i;
uint8_t small_buf[1];
for (i = 0; i < bc; i++) {
    nrf_drv_spi_transfer(&spi, NULL, 0, small_buf, 1);
    buff[i] = small_buf[0];
}

Electronic – I2C communication won’t start unless SDA pullup resistor is reinserted

Your problem is that you have sprinkled i2c_wait() commands through your code.

This is a microcontroller, it is simple, it does exactly what you want. The state doesn't need to be constantly checked. You should only need to call i2c_wait() after interacting with SSPBUF. Have a look at http://www.8051projects.net/wiki/I2C_Implementation_on_PIC

By holding SCL high and toggling SDA (removing and replacing the resistor) you are sending a start bit followed by a stop bit. It isn't clear why this fixes the registers you are checking, as Chris Stratton suggested you could dump out the registers if you really cared.

Best Answer

Related Solutions

Electronic – FatFs: Why am I not able to properly read sector 0

Electronic – I2C communication won’t start unless SDA pullup resistor is reinserted

Related Topic