int sd_send_command(unsigned char cmd, uint32_t arg)
{
unsigned char n, res, *p;
if (cmd & 0x80) { /* ACMD<n> is the command sequense of CMD55-CMD<n> */
cmd &= 0x7F;
res = sd_send_command(CMD55, 0);
if (res > 1)
return res;
}
/* Select the card and wait for ready */
sd_spi_release(); /* raise CS, then sends 8 clocks (some cards require this) */
sd_spi_lower_cs();
if(sd_spi_wait(true) != 0xFF)
return 0xFF;
/* Send command packet */
sd_spi_transmit_byte(cmd); /* Start + Command index */
#if 0
sd_spi_transmit_byte((unsigned char)(arg >> 24)); /* Argument[31..24] */
sd_spi_transmit_byte((unsigned char)(arg >> 16)); /* Argument[23..16] */
sd_spi_transmit_byte((unsigned char)(arg >> 8)); /* Argument[15..8] */
sd_spi_transmit_byte((unsigned char)arg); /* Argument[7..0] */
#else
/* sdcc sadly unable to figure this out for itself yet */
p = ((unsigned char *)&arg)+3;
sd_spi_transmit_byte(*(p--)); /* Argument[31..24] */
sd_spi_transmit_byte(*(p--)); /* Argument[23..16] */
sd_spi_transmit_byte(*(p--)); /* Argument[15..8] */
sd_spi_transmit_byte(*p); /* Argument[7..0] */
#endif
/* there's only a few commands (in native mode) that need correct CRCs */
n = 0x01; /* Dummy CRC + Stop */
if (cmd == CMD0) n = 0x95; /* Valid CRC for CMD0(0) */
if (cmd == CMD8) n = 0x87; /* Valid CRC for CMD8(0x1AA) */
sd_spi_transmit_byte(n);
/* Receive command response */
if (cmd == CMD12)
sd_spi_receive_byte(); /* Skip a stuff byte when stop reading */
n = 20; /* Wait for a valid response */
do {
res = sd_spi_receive_byte();
} while ((res & 0x80) && --n);
return res; /* Return with the response value */
}
uint8_t devsd_transfer_sector1(void)
{
uint8_t attempt;
bool success;
sd_drive = blk_op.blkdev->driver_data & DRIVE_NR_MASK;
for(attempt=0; attempt<8; attempt++){
if(sd_send_command(blk_op.is_read ? CMD17 : CMD24,
/* for byte addressed cards, shift LBA to convert to byte address */
(blk_op.blkdev->driver_data & CT_BLOCK) ? blk_op.lba : (blk_op.lba << 9)
) == 0){
if(blk_op.is_read){
success = (sd_spi_wait(false) == 0xFE);
if(success){
sd_spi_receive_sector();
//sd_spi_wait(false);
}
}else{
success = false;
if(sd_spi_wait(true) == 0xFF){
sd_spi_transmit_byte(0xFE);
sd_spi_transmit_sector();
sd_spi_transmit_byte(0xFF); /* dummy CRC */
sd_spi_transmit_byte(0xFF);
success = ((sd_spi_wait(false) & 0x1F) == 0x05);
}
}
}else
success = false;
sd_spi_release();
if(success)
return 1;
kputs("sd: failed, retrying.\n");
}
udata.u_error = EIO;
return 0;
}