sd_raw.c

SD卡和FAT16读写源代码 支持长文件名和子目录

#include <avr/io.h>
#include "sd_raw.h"

#if !SD_RAW_SAVE_RAM
#include <string.h>
#endif

/**
 * \addtogroup sd_raw MMC/SD card raw access
 *
 * This module implements read and write access to MMC and
 * SD cards. It serves as a low-level driver for the higher
 * level modules such as partition and file system access.
 *
 * @{
 */
/**
 * \file
 * MMC/SD raw access implementation.
 *
 * \author Roland Riegel
 */

/**
 * \addtogroup sd_raw_config MMC/SD configuration
 * Preprocessor defines to configure the MMC/SD support.
 */

/**
 * @}
 */

/* commands available in SPI mode */

/* CMD0: response R1 */
#define CMD_GO_IDLE_STATE 0x00
/* CMD1: response R1 */
#define CMD_SEND_OP_COND 0x01
/* CMD9: response R1 */
#define CMD_SEND_CSD 0x09
/* CMD10: response R1 */
#define CMD_SEND_CID 0x0a
/* CMD12: response R1 */
#define CMD_STOP_TRANSMISSION 0x0c
/* CMD13: response R2 */
#define CMD_SEND_STATUS 0x0d
/* CMD16: arg0[31:0]: block length, response R1 */
#define CMD_SET_BLOCKLEN 0x10
/* CMD17: arg0[31:0]: data address, response R1 */
#define CMD_READ_SINGLE_BLOCK 0x11
/* CMD18: arg0[31:0]: data address, response R1 */
#define CMD_READ_MULTIPLE_BLOCK 0x12
/* CMD24: arg0[31:0]: data address, response R1 */
#define CMD_WRITE_SINGLE_BLOCK 0x18
/* CMD25: arg0[31:0]: data address, response R1 */
#define CMD_WRITE_MULTIPLE_BLOCK 0x19
/* CMD27: response R1 */
#define CMD_PROGRAM_CSD 0x1b
/* CMD28: arg0[31:0]: data address, response R1b */
#define CMD_SET_WRITE_PROT 0x1c
/* CMD29: arg0[31:0]: data address, response R1b */
#define CMD_CLR_WRITE_PROT 0x1d
/* CMD30: arg0[31:0]: write protect data address, response R1 */
#define CMD_SEND_WRITE_PROT 0x1e
/* CMD32: arg0[31:0]: data address, response R1 */
#define CMD_TAG_SECTOR_START 0x20
/* CMD33: arg0[31:0]: data address, response R1 */
#define CMD_TAG_SECTOR_END 0x21
/* CMD34: arg0[31:0]: data address, response R1 */
#define CMD_UNTAG_SECTOR 0x22
/* CMD35: arg0[31:0]: data address, response R1 */
#define CMD_TAG_ERASE_GROUP_START 0x23
/* CMD36: arg0[31:0]: data address, response R1 */
#define CMD_TAG_ERASE_GROUP_END 0x24
/* CMD37: arg0[31:0]: data address, response R1 */
#define CMD_UNTAG_ERASE_GROUP 0x25
/* CMD38: arg0[31:0]: stuff bits, response R1b */
#define CMD_ERASE 0x26
/* CMD42: arg0[31:0]: stuff bits, response R1b */
#define CMD_LOCK_UNLOCK 0x2a
/* CMD58: response R3 */
#define CMD_READ_OCR 0x3a
/* CMD59: arg0[31:1]: stuff bits, arg0[0:0]: crc option, response R1 */
#define CMD_CRC_ON_OFF 0x3b

/* command responses */
/* R1: size 1 byte */
#define R1_IDLE_STATE 0
#define R1_ERASE_RESET 1
#define R1_ILL_COMMAND 2
#define R1_COM_CRC_ERR 3
#define R1_ERASE_SEQ_ERR 4
#define R1_ADDR_ERR 5
#define R1_PARAM_ERR 6
/* R1b: equals R1, additional busy bytes */
/* R2: size 2 bytes */
#define R2_CARD_LOCKED 0
#define R2_WP_ERASE_SKIP 1
#define R2_ERR 2
#define R2_CARD_ERR 3
#define R2_CARD_ECC_FAIL 4
#define R2_WP_VIOLATION 5
#define R2_INVAL_ERASE 6
#define R2_OUT_OF_RANGE 7
#define R2_CSD_OVERWRITE 7
#define R2_IDLE_STATE (R1_IDLE_STATE + 8)
#define R2_ERASE_RESET (R1_ERASE_RESET + 8)
#define R2_ILL_COMMAND (R1_ILL_COMMAND + 8)
#define R2_COM_CRC_ERR (R1_COM_CRC_ERR + 8)
#define R2_ERASE_SEQ_ERR (R1_ERASE_SEQ_ERR + 8)
#define R2_ADDR_ERR (R1_ADDR_ERR + 8)
#define R2_PARAM_ERR (R1_PARAM_ERR + 8)
/* R3: size 5 bytes */
#define R3_OCR_MASK (0xffffffffUL)
#define R3_IDLE_STATE (R1_IDLE_STATE + 32)
#define R3_ERASE_RESET (R1_ERASE_RESET + 32)
#define R3_ILL_COMMAND (R1_ILL_COMMAND + 32)
#define R3_COM_CRC_ERR (R1_COM_CRC_ERR + 32)
#define R3_ERASE_SEQ_ERR (R1_ERASE_SEQ_ERR + 32)
#define R3_ADDR_ERR (R1_ADDR_ERR + 32)
#define R3_PARAM_ERR (R1_PARAM_ERR + 32)
/* Data Response: size 1 byte */
#define DR_STATUS_MASK 0x0e
#define DR_STATUS_ACCEPTED 0x05
#define DR_STATUS_CRC_ERR 0x0a
#define DR_STATUS_WRITE_ERR 0x0c

#if !SD_RAW_SAVE_RAM

/* static data buffer for acceleration */
static uint8_t raw_block[512];
/* offset where the data within raw_block lies on the card */
static uint32_t raw_block_address;

#endif

/* private helper functions */
static void sd_raw_send_byte(uint8_t b);
static uint8_t sd_raw_rec_byte();
static uint8_t sd_raw_send_command_r1(uint8_t command, uint32_t arg);
static uint16_t sd_raw_send_command_r2(uint8_t command, uint32_t arg);

/**
 * \ingroup sd_raw
 * Initializes memory card communication.
 *
 * \returns 0 on failure, 1 on success.
 */
uint8_t sd_raw_init()
{
    /* enable inputs for reading card status */
    configure_pin_available();
    configure_pin_locked();

    /* enable outputs for MOSI, SCK, SS, input for MISO */
    configure_pin_mosi();
    configure_pin_sck();
    configure_pin_ss();
    configure_pin_miso();
    unselect_card();

    SPCR |= (0 << SPIE) | /* SPI Interrupt Enable */
            (1 << SPE)  | /* SPI Enable */
            (0 << DORD) | /* Data Order: MSB first */
            (1 << MSTR) | /* Master mode */
            (0 << CPOL) | /* Clock Polarity: SCK low when idle */
            (0 << CPHA) | /* Clock Phase: sample on rising SCK edge */
            (1 << SPR1) | /* Clock Frequency: f_OSC / 64 */
            (0 << SPR0);

    /* initialization procedure */
    
    if(!sd_raw_available())
        return 0;

    /* the card needs 74 cycles minimum to start up */
    for(int i = 0; i < 10; ++i)
    {
        /* wait 8 clock cycles */
        sd_raw_rec_byte();
    }

    /* address card */
    select_card();

    /* reset card */
    sd_raw_send_command_r1(CMD_GO_IDLE_STATE, 0);
    
    /* wait for card to get ready */
    uint8_t response;
    for(int i = 0; i < 10; ++i)
    {
        response = sd_raw_send_command_r1(CMD_SEND_OP_COND, 0);
        if(!(response & (1 << R1_IDLE_STATE)))
            break;
    }

    /* set block size to 512 bytes */
    if(sd_raw_send_command_r1(CMD_SET_BLOCKLEN, 512))
    {
        unselect_card();
        return 0;
    }

    /* deaddress card */
    unselect_card();

#if !SD_RAW_SAVE_RAM
    /* the first block is likely to be accessed first, so precache it here */
    raw_block_address = 0xffffffff;
    if(!sd_raw_read(0, raw_block, sizeof(raw_block)))
        return 0;
#endif

    return 1;
}

/**
 * \ingroup sd_raw
 * Checks wether a memory card is located in the slot.
 *
 * \returns 1 if the card is available, 0 if it is not.
 */
uint8_t sd_raw_available()
{
    return get_pin_available() == 0x00;
}

/**
 * \ingroup sd_raw
 * Checks wether the memory card is locked for write access.
 *
 * \returns 1 if the card is locked, 0 if it is not.
 */
uint8_t sd_raw_locked()
{
    return get_pin_locked() == 0x00;
}

/**
 * \ingroup sd_raw
 * Sends a raw byte to the memory card.
 *
 * \param[in] b The byte to sent.
 * \see sd_raw_rec_byte
 */
void sd_raw_send_byte(uint8_t b)
{
    SPDR = b;
    /* wait for byte to be shifted out */
    while(!(SPSR & (1 << SPIF)));
    SPSR &= ~(1 << SPIF);
}

/**
 * \ingroup sd_raw
 * Receives a raw byte from the memory card.
 *
 * \returns The byte which should be read.
 * \see sd_raw_send_byte
 */
uint8_t sd_raw_rec_byte()
{
    /* send dummy data for receiving some */
    SPDR = 0xff;
    while(!(SPSR & (1 << SPIF)));
    SPSR &= ~(1 << SPIF);

    return SPDR;
}

/**
 * \ingroup sd_raw
 * Send a command to the memory card which responses with a R1 response.
 *
 * \param[in] command The command to send.
 * \param[in] arg The argument for command.
 * \returns The command answer.
 */
uint8_t sd_raw_send_command_r1(uint8_t command, uint32_t arg)
{
    uint8_t response;

    /* wait some clock cycles */
    sd_raw_rec_byte();

    /* send command via SPI */
    sd_raw_send_byte(0x40 | command);
    sd_raw_send_byte((arg >> 24) & 0xff);
    sd_raw_send_byte((arg >> 16) & 0xff);
    sd_raw_send_byte((arg >> 8) & 0xff);
    sd_raw_send_byte((arg >> 0) & 0xff);
    sd_raw_send_byte(command == CMD_GO_IDLE_STATE ? 0x95 : 0xff);
    
    /* receive response */
    for(int i = 0; i < 10; ++i)
    {
        response = sd_raw_rec_byte();
        if(response != 0xff)
            break;
    }

    /* the card internally needs eight further clock cycles */
    sd_raw_rec_byte();

    return response;
}

/**
 * \ingroup sd_raw
 * Send a command to the memory card which responses with a R2 response.
 *
 * \param[in] command The command to send.
 * \param[in] arg The argument for command.
 * \returns The command answer.
 */
uint16_t sd_raw_send_command_r2(uint8_t command, uint32_t arg)
{