sdcard.c

#include <avr/io.h>
#include <util/delay.h>
#include <avr/pgmspace.h>
#include "sdcard.h"
#include "sdprint.h"
#include "spi.h"
#include "uart.h"

/*******************************************************************************
 Initialize SD card
*******************************************************************************/
uint8_t SD_init()
{
    uint8_t res[5], cmdAttempts = 0;

    SD_powerUpSeq();

    while((res[0] = SD_goIdleState()) != SD_IN_IDLE_STATE)
    {
        cmdAttempts++;
        if(cmdAttempts == CMD0_MAX_ATTEMPTS)
        {
            return SD_ERROR;
        }
    }

    _delay_ms(1);

    SD_sendIfCond(res);
    if(res[0] != SD_IN_IDLE_STATE)
    {
        return SD_ERROR;
    }

    if(res[4] != 0xAA)
    {
        return SD_ERROR;
    }

    cmdAttempts = 0;
    do
    {
        if(cmdAttempts == CMD55_MAX_ATTEMPTS)
        {
            return SD_ERROR;
        }

        res[0] = SD_sendApp();
        if(SD_R1_NO_ERROR(res[0]))
        {
            res[0] = SD_sendOpCond();
        }

        _delay_ms(1);

        cmdAttempts++;
    }
    while(res[0] != SD_READY);

    _delay_ms(1);

    SD_readOCR(res);

    SPI_init(SPI_MASTER | SPI_FOSC_4 | SPI_MODE_0);

    return SD_SUCCESS;
}

/*******************************************************************************
 Run power up sequence
*******************************************************************************/
void SD_powerUpSeq()
{
    // make sure card is deselected
    CS_DISABLE();

    // give SD card time to power up
    _delay_ms(10);

    // select SD card
    SPI_transfer(0xFF);
    CS_DISABLE();

    // send 80 clock cycles to synchronize
    for(uint8_t i = 0; i < SD_INIT_CYCLES; i++)
        SPI_transfer(0xFF);
}

/*******************************************************************************
 Send command to SD card
*******************************************************************************/
void SD_command(uint8_t cmd, uint32_t arg, uint8_t crc)
{
    // transmit command to sd card
    SPI_transfer(cmd|0x40);

    // transmit argument
    SPI_transfer((uint8_t)(arg >> 24));
    SPI_transfer((uint8_t)(arg >> 16));
    SPI_transfer((uint8_t)(arg >> 8));
    SPI_transfer((uint8_t)(arg));

    // transmit crc
    SPI_transfer(crc|0x01);
}

/*******************************************************************************
 Read R1 from SD card
*******************************************************************************/
uint8_t SD_readRes1()
{
    uint8_t i = 0, res1;

    // keep polling until actual data received
    while((res1 = SPI_transfer(0xFF)) == 0xFF)
    {
        i++;

        // if no data received for 8 bytes, break
        if(i > 8) break;
    }

    return res1;
}

/*******************************************************************************
 Read R2 from SD card
*******************************************************************************/
void SD_readRes2(uint8_t *res)
{
    // read response 1 in R2
    res[0] = SD_readRes1();

    // read final byte of response
    res[1] = SPI_transfer(0xFF);
}

/*******************************************************************************
 Read R3 from SD card
*******************************************************************************/
void SD_readRes3(uint8_t *res)
{
    // read response 1 in R3
    res[0] = SD_readRes1();

    // if error reading R1, return
    if(res[0] > 1) return;

    // read remaining bytes
    SD_readBytes(res + 1, R3_BYTES);
}

/*******************************************************************************
 Read R7 from SD card
*******************************************************************************/
void SD_readRes7(uint8_t *res)
{
    // read response 1 in R7
    res[0] = SD_readRes1();

    // if error reading R1, return
    if(res[0] > 1) return;

    // read remaining bytes
    SD_readBytes(res + 1, R7_BYTES);
}

/*******************************************************************************
 Read specified number of bytes from SD card
*******************************************************************************/
void SD_readBytes(uint8_t *res, uint8_t n)
{
    while(n--) *res++ = SPI_transfer(0xFF);
}

/*******************************************************************************
 Command Idle State (CMD0)
*******************************************************************************/
uint8_t SD_goIdleState()
{
    // assert chip select
    SPI_transfer(0xFF);
    CS_ENABLE();
    SPI_transfer(0xFF);

    // send CMD0
    SD_command(CMD0, CMD0_ARG, CMD0_CRC);

    // read response
    uint8_t res1 = SD_readRes1();

    // deassert chip select
    SPI_transfer(0xFF);
    CS_DISABLE();
    SPI_transfer(0xFF);

    return res1;
}

/*******************************************************************************
 Send Interface Conditions (CMD8)
*******************************************************************************/
void SD_sendIfCond(uint8_t *res)
{
    // assert chip select
    SPI_transfer(0xFF);
    CS_ENABLE();
    SPI_transfer(0xFF);

    // send CMD8
    SD_command(CMD8, CMD8_ARG, CMD8_CRC);

    // read response
    SD_readRes7(res);
    //SD_readBytes(res + 1, R7_BYTES);

    // deassert chip select
    SPI_transfer(0xFF);
    CS_DISABLE();
    SPI_transfer(0xFF);
}

/*******************************************************************************
 Read Status
*******************************************************************************/
void SD_sendStatus(uint8_t *res)
{
    // assert chip select
    SPI_transfer(0xFF);
    CS_ENABLE();
    SPI_transfer(0xFF);

    // send CMD13
    SD_command(CMD13, CMD13_ARG, CMD13_CRC);

    // read response
    SD_readRes2(res);

    // deassert chip select
    SPI_transfer(0xFF);
    CS_DISABLE();
    SPI_transfer(0xFF);
}

/*******************************************************************************
 Read single 512 byte block
 token = 0xFE - Successful read
 token = 0x0X - Data error
 token = 0xFF - timeout
*******************************************************************************/
uint8_t SD_readSingleBlock(uint32_t addr, uint8_t *buf, uint8_t *token)
{
    uint8_t res1, read;
    uint16_t readAttempts;

    // set token to none
    *token = 0xFF;

    // assert chip select
    SPI_transfer(0xFF);
    CS_ENABLE();
    SPI_transfer(0xFF);

    // send CMD17
    SD_command(CMD17, addr, CMD17_CRC);

    // read R1
    res1 = SD_readRes1();

    // if response received from card
    if(res1 != 0xFF)
    {
        // wait for a response token (timeout = 100ms)
        readAttempts = 0;
        while(++readAttempts != SD_MAX_READ_ATTEMPTS)
            if((read = SPI_transfer(0xFF)) != 0xFF) break;

        // if response token is 0xFE
        if(read == SD_START_TOKEN)
        {
            // read 512 byte block
            for(uint16_t i = 0; i < SD_BLOCK_LEN; i++) *buf++ = SPI_transfer(0xFF);

            // read 16-bit CRC
            SPI_transfer(0xFF);
            SPI_transfer(0xFF);
        }

        // set token to card response
        *token = read;
    }

    // deassert chip select
    SPI_transfer(0xFF);
    CS_DISABLE();
    SPI_transfer(0xFF);

    return res1;
}

#define SD_MAX_WRITE_ATTEMPTS   3907

/*******************************************************************************
Write single 512 byte block
token = 0x00 - busy timeout
token = 0x05 - data accepted
token = 0xFF - response timeout
*******************************************************************************/
uint8_t SD_writeSingleBlock(uint32_t addr, uint8_t *buf, uint8_t *token)
{
    uint16_t readAttempts;
    uint8_t res1, read;

    // set token to none
    *token = 0xFF;

    // assert chip select
    SPI_transfer(0xFF);
    CS_ENABLE();
    SPI_transfer(0xFF);

    // send CMD24
    SD_command(CMD24, addr, CMD24_CRC);

    // read response
    res1 = SD_readRes1();

    // if no error
    if(res1 == SD_READY)
    {
        // send start token
        SPI_transfer(SD_START_TOKEN);

        // write buffer to card
        for(uint16_t i = 0; i < SD_BLOCK_LEN; i++) SPI_transfer(buf[i]);

        // wait for a response (timeout = 250ms)
        readAttempts = 0;
        while(++readAttempts != SD_MAX_WRITE_ATTEMPTS)
            if((read = SPI_transfer(0xFF)) != 0xFF) { *token = 0xFF; break; }

        // if data accepted
        if((read & 0x1F) == 0x05)
        {
            // set token to data accepted
            *token = 0x05;

            // wait for write to finish (timeout = 250ms)
            readAttempts = 0;
            while(SPI_transfer(0xFF) == 0x00)
                if(++readAttempts == SD_MAX_WRITE_ATTEMPTS) { *token = 0x00; break; }
        }
    }

    // deassert chip select
    SPI_transfer(0xFF);
    CS_DISABLE();
    SPI_transfer(0xFF);

    return res1;
}

/*******************************************************************************
 Reads OCR from SD Card
*******************************************************************************/
void SD_readOCR(uint8_t *res)
{
    // assert chip select
    SPI_transfer(0xFF);
    CS_ENABLE();
    uint8_t tmp = SPI_transfer(0xFF);

    if(tmp != 0xFF) while(SPI_transfer(0xFF) != 0xFF) ;

    // send CMD58
    SD_command(CMD58, CMD58_ARG, CMD58_CRC);

    // read response
    SD_readRes3(res);

    // deassert chip select
    SPI_transfer(0xFF);
    CS_DISABLE();
    SPI_transfer(0xFF);
}

/*******************************************************************************
 Send application command (CMD55)
*******************************************************************************/
uint8_t SD_sendApp()
{
    // assert chip select
    SPI_transfer(0xFF);
    CS_ENABLE();
    SPI_transfer(0xFF);

    // send CMD0
    SD_command(CMD55, CMD55_ARG, CMD55_CRC);

    // read response
    uint8_t res1 = SD_readRes1();

    // deassert chip select
    SPI_transfer(0xFF);
    CS_DISABLE();
    SPI_transfer(0xFF);

    return res1;
}

/*******************************************************************************
 Send operating condition (ACMD41)
*******************************************************************************/
uint8_t SD_sendOpCond()
{
    // assert chip select
    SPI_transfer(0xFF);
    CS_ENABLE();
    SPI_transfer(0xFF);

    // send CMD0
    SD_command(ACMD41, ACMD41_ARG, ACMD41_CRC);

    // read response
    uint8_t res1 = SD_readRes1();

    // deassert chip select
    SPI_transfer(0xFF);
    CS_DISABLE();
    SPI_transfer(0xFF);

    return res1;
}