1

I get invalid response codes from my SD card (CMD8, CMD55, and CMD41).

Init routine:

SDCS = 1; // MMC deaktiviert
SPI1CON1bits.SMP = 0;
SPI1CON1bits.CKE = 1;
SPI1CON1bits.MSTEN = 1;
SPI1CON1bits.CKP = 0;
SPI1STATbits.SPIEN = 1;

for(i=0; i<10; i++)
    SPI(0xFF);

// RESET
unsigned char rr=Command(CMD0,0);
SDCS=1; // MMC deactivated
/* OK response == 1 */

r = Command(CMD8,0); // Check voltage
SDCS=1;
/*
  esponse ==  0xC1 ?!?
*/

r = Command(CMD58,0); // READ_OCR

unsigned char ocr1 = SPI(0xFF);
unsigned char ocr2 = SPI(0xFF);
unsigned char ocr3 = SPI(0xFF);
unsigned char ocr4 = SPI(0xFF);
unsigned char ocr5 = SPI(0xFF);

/*
  r = 0xF8; ?!?
  ocr1 = 0x0F;
  ocr2 = 0xFF;
  ocr3 = 0xFF;
  ocr4 = 0xFF;
  ocr5 = 0xFF;
*/

SDCS=1;

// INIT
unsigned char rrr = 0;
i = 10000;
do
{
    rrr = Command(55,0); // Next is APP CMD
    SDCS = 1;
    if(r)
        break;
} while(--i>0);

/*
OK response == 1
*/

// APP CMD 41 with OCR = 0x0F??

You can read the response codes in the comments.

Is it possible the response code to CMD8 is 0xC1? Bit 7 should be 0, right?

Is it a hardware error?

Peter Mortensen
  • 30,738
  • 21
  • 105
  • 131
Ich
  • 19
  • 1
  • 4

1 Answers1

1

The solution can be found in Stack Overflow question Initializing SD card in SPI issues.

In short: Before each command (except CMD0), send 0xFF until you get 0xFF as a response.

Community
  • 1
  • 1
Turbo J
  • 7,563
  • 1
  • 23
  • 43