DRESULT disk_readp (
BYTE* dest, /* Pointer to the destination object */
DWORD sector, /* Sector number (LBA) */
WORD sofs, /* Offset in the sector */
WORD count /* Byte count (bit15:destination) */
)
{
DRESULT res;
USHORT timeout;
USHORT bytes_to_read;
select_card();
if(!(card_type & CT_BLOCK)) sector *= 512;
res = RES_ERROR;
if(send_cmd(CMD_17, sector, 0x00) != 0){
deselect_card();
return RES_ERROR;
}
timeout = 4000;
while((rec_byte() != 0xFE) && timeout--){}
if(timeout){
bytes_to_read = 514 - sofs - count;
//Pass through offset
if(sofs){
do{
rec_byte();
}while(--sofs); //Debug: check this
}
//get requested data bytes
if(dest){
do {
*dest++ = rec_byte();
} while (--count);
}else{
do {
rec_byte();//DEBUG: Not sure if i need this. Examples uses FORWARD(rec_byte()); for communication with a computer
}while(--count);
}
//skip over trailing bytes
do {
rec_byte();
}while(--bytes_to_read);
res = RES_OK;
}//close if timeout
deselect_card();
rec_byte();
return res;
}
tCardInfo *mmc_card_info(int card_no)
{
tCardInfo *card = &card_info[card_no];
if (!card->initialized && ((card_no == 0) || mmc_detect()))
{
select_card(card_no);
deselect_card();
}
return card;
}
DRESULT disk_writep (
const BYTE* buff, /* Pointer to the data to be written, NULL:Initiate/Finalize write operation */
DWORD sc /* Sector number (LBA) or Number of bytes to send */
)
{
DRESULT res;
WORD byte_count;
static WORD bytes_left_in_block; //counter used to write data
select_card();
res = RES_ERROR;
if (buff) {
byte_count = (WORD)sc;
while(bytes_left_in_block && byte_count){
send_byte(*buff++);
byte_count--;
bytes_left_in_block--;
}//end of while
res = RES_OK;
}//end of if(buf)
else if (sc) {
if(!(card_type & CT_BLOCK))
sc *= 512; //multiply address by 512 if the card is byte addrssed
if(send_cmd(WRITE_BLOCK, sc, 0x00) == 0){
send_byte(0xFF); //Send header byte 1
send_byte(0xFE); //Send header byte 2
bytes_left_in_block = 512;
}
res = RES_OK;
}//end of 1st else
else{
fill_zeros(bytes_left_in_block);
res = check_write_success();
deselect_card();
}//end 2nd else
return res;
}//End of writep
//This function assumes the SD card has been powered for at least a second before being called
DSTATUS disk_initialize (void)
{
unsigned i;
init_spi();
init_card_select_pin();
//pull CS high, then send at least 74 clock pulses to the module with SIMO high
deselect_card();
for(i = 0; i <= 10; i++){
rec_byte();
}
//pull CS low and send CMD0 to reset card and put it in SPI mode
select_card();
if (send_cmd(CMD_0, 0x00000000, 0x95) != 1){
deselect_card();
return RES_ERROR;
}
if(send_cmd(CMD_8, 0x000001AA, 0x87) == 1){ //Check voltage range on card. If a non-one value is returned, card is not sd v.2
if(get_r7_resp(0xAA) != RES_OK){ //returns 1 if card works at 2.7-3.3V and check_pattern is valid
deselect_card();
return RES_ERROR;
}
if(check_ocr_voltage_range() != RES_OK){
deselect_card();
return RES_ERROR;
}
if(wait_for_card_to_finish_init() != RES_OK){
deselect_card();
return RES_ERROR;
}
if(check_card_type() != RES_OK){
deselect_card();
return RES_ERROR;
}
}//close if cmd_8
//else{
//}//Version 1.0 or earlier
deselect_card();
return RES_OK;
}
