Posted on March 11, 2016 at 20:08Hi to all,
I have a big issue with SD cards.
I initialize correctly my sd card, but when I try to read a block, I can read it only the first time.
This is my routine:
=====================
uint32_t MYSD::ReadSector(uint32_t sector, uint8_t *block)
{
uint8_t t;
uint16_t i;
GPIOA->BRR = 0x01<<SDSS0; // Set SDSS0 low
t = CommandAndResponse(SPICMD17, sector); //Read sector command
if(t != 0)
{
GPIOA->BSRR = 0x01<<SDSS0; // Set SDSS0 high
myusart1.PrintString((uint8_t *) ''Cannot read (CMD17)'', ' ', 0);
myusart1.PrintHex8(t);
myusart1.PrintChar('\n');
return 1;
}
do
{
t = sp->Transfer8(0xFF, 0, 0); // Wait for card response
}
while(t == 0xFF);
if(t != 0xFE)
{
GPIOA->BSRR = 0x01<<SDSS0; // Set SDSS0 high
myusart1.PrintString((uint8_t *) ''Cannot read (Token response)'', ' ', 0);
myusart1.PrintHex8(t);
myusart1.PrintChar('\n');
return 2;
}
for(i=0; i<512; i++) block[i] = sp->Transfer8(0xFF, 0, 0); //Read data
t = sp->Transfer8(0xFF, 0, 1); // Read CRC
t = sp->Transfer8(0xFF, 0, 1); // Read CRC
GPIOA->BSRR = 0x01<<SDSS0; // Set SDSS0 high
return 0;
}
=====================
and this is the tesponse:
Iteration 1: CMD17 response 0
Iteration 2: CMD17 response 4
Iteration 3: CMD17 response 0
Iteration 4: CMD17 response 4
Iteration 5: CMD17 response 0
Iteration 6: CMD17 response 4
Iteration 7: CMD17 response 0
Why I can read block in odd iterations and not in even? The routine is always the same.
Anyone encountered the same problem?
Thank you
Freya
