File syn_sd.c¶

FileList > drivers > syn_sd.c

SD card SPI block driver implementation. More...

#include "../util/syn_assert.h"
#include "syn_sd.h"
#include <string.h>

Public Functions¶

Type	Name
SYN_Status	syn_sd_init (SYN_SD * sd, uint8_t spi_bus, SYN_GPIO_Pin cs) Initialize the SD card over SPI.
SYN_Status	syn_sd_read (const SYN_SD * sd, uint32_t sector, uint8_t * buf) Read one 512-byte sector from the SD card (CMD17).
uint32_t	syn_sd_sectors (const SYN_SD * sd) Return total sector count parsed from the CSD register.
SYN_Status	syn_sd_sync (const SYN_SD * sd) Flush the write pipeline — wait until card is idle (CMD13).
SYN_SD_Type	syn_sd_type (const SYN_SD * sd) Return the detected card type.
SYN_Status	syn_sd_write (const SYN_SD * sd, uint32_t sector, const uint8_t * buf) Write one 512-byte sector to the SD card (CMD24).

Public Static Functions¶

Type	Name
uint8_t	sd_cmd (const SYN_SD * sd, uint8_t cmd, uint32_t arg, uint8_t crc) Send a 6-byte SD command and poll for R1 response.
SYN_Status	sd_read_csd (SYN_SD * sd) Read the CSD register and parse sector count.
bool	sd_wait_ready (const SYN_SD * sd) Wait until the SD card is no longer busy (MISO = 0xFF).
uint8_t	sd_xfer (const SYN_SD * sd, uint8_t out) Transfer one byte over SPI and return the received byte.

Macros¶

Type	Name
define	SD_ACMD41 `41u`
define	SD_ACMD41_RETRIES `1000u`
define	SD_BUSY_RETRIES `2000u`
define	SD_CMD0 `0u`
define	SD_CMD13 `13u`
define	SD_CMD16 `16u`
define	SD_CMD17 `17u`
define	SD_CMD24 `24u`
define	SD_CMD55 `55u`
define	SD_CMD58 `58u`
define	SD_CMD8 `8u`
define	SD_CMD9 `9u`
define	SD_R1_ERR_MSK `0xFEu`
define	SD_R1_IDLE `0x01u`
define	SD_R1_ILLCMD `0x04u`
define	SD_R1_POLL_RETRIES `8u`
define	SD_R1_READY `0x00u`
define	SD_R1_TIMEOUT `0xFFu`
define	SD_TOKEN_ACCEPTED `0x05u`
define	SD_TOKEN_RETRIES `2000u`
define	SD_TOKEN_START `0xFEu`

Detailed Description¶

Implements the SD simplified SPI spec: * CMD0 (GO_IDLE_STATE) reset to SPI mode * CMD8 (SEND_IF_COND) SDHC-capable detection * CMD9 (SEND_CSD) capacity via CSD v1/v2 parse * CMD13 (SEND_STATUS) sync / flush * CMD16 (SET_BLOCKLEN) SDSC: force 512-byte blocks * CMD17 (READ_SINGLE_BLOCK) * CMD24 (WRITE_BLOCK) * CMD55 (APP_CMD) ACMD prefix * CMD58 (READ_OCR) card type confirmation * ACMD41 (SD_SEND_OP_COND) card initialization

CRC: CMD0/CMD8 use hardcoded CRC7 constants. All other commands and data blocks use 0xFF dummy bytes (CRC mode off by default in SPI).

Public Functions Documentation¶

function syn_sd_init¶

Initialize the SD card over SPI.

SYN_Status syn_sd_init (
    SYN_SD * sd,
    uint8_t spi_bus,
    SYN_GPIO_Pin cs
)

Performs power-up clocking, CMD0/CMD8/ACMD41 init, type detection via CMD58, and CSD parsing for capacity.

Parameters:

sd Pointer to a caller-owned SYN_SD struct.
spi_bus SPI bus index passed to syn_port_spi_*.
cs Chip-select GPIO pin (active-low).

Returns:

SYN_OK on success, SYN_ERROR if no card or init failed.

function syn_sd_read¶

Read one 512-byte sector from the SD card (CMD17).

SYN_Status syn_sd_read (
    const SYN_SD * sd,
    uint32_t sector,
    uint8_t * buf
)

Parameters:

sd Initialized SD handle.
sector Zero-based sector index.
buf Output buffer — caller must provide at least 512 bytes.

Returns:

SYN_OK on success, SYN_ERROR on timeout or card error.

function syn_sd_sectors¶

Return total sector count parsed from the CSD register.

uint32_t syn_sd_sectors (
    const SYN_SD * sd
)

Parameters:

sd Initialized SD handle.

Returns:

Number of 512-byte sectors on the card.

function syn_sd_sync¶

Flush the write pipeline — wait until card is idle (CMD13).

SYN_Status syn_sd_sync (
    const SYN_SD * sd
)

Parameters:

sd Initialized SD handle.

Returns:

SYN_OK if card is idle and error-free, SYN_ERROR otherwise.

function syn_sd_type¶

Return the detected card type.

SYN_SD_Type syn_sd_type (
    const SYN_SD * sd
)

Parameters:

sd Initialized SD handle.

Returns:

SYN_SD_SDSC or SYN_SD_SDHC.

function syn_sd_write¶

Write one 512-byte sector to the SD card (CMD24).

SYN_Status syn_sd_write (
    const SYN_SD * sd,
    uint32_t sector,
    const uint8_t * buf
)

Parameters:

sd Initialized SD handle.
sector Zero-based sector index.
buf Data to write — must be exactly 512 bytes.

Returns:

SYN_OK on success, SYN_ERROR on card rejection or timeout.

Public Static Functions Documentation¶

function sd_cmd¶

Send a 6-byte SD command and poll for R1 response.

static uint8_t sd_cmd (
    const SYN_SD * sd,
    uint8_t cmd,
    uint32_t arg,
    uint8_t crc
)

Parameters:

sd SD card instance.
cmd Command index (e.g. CMD0).
arg 32-bit argument.
crc CRC byte.

Returns:

R1 response byte.

function sd_read_csd¶

Read the CSD register and parse sector count.

static SYN_Status sd_read_csd (
    SYN_SD * sd
)

Parameters:

sd SD card instance.

Returns:

SYN_OK on success.

function sd_wait_ready¶

Wait until the SD card is no longer busy (MISO = 0xFF).

static bool sd_wait_ready (
    const SYN_SD * sd
)

Parameters:

sd SD card instance.

Returns:

true if card became ready within timeout.

function sd_xfer¶

Transfer one byte over SPI and return the received byte.

static uint8_t sd_xfer (
    const SYN_SD * sd,
    uint8_t out
)

Parameters:

sd SD card instance.
out Byte to send.

Returns:

Received byte.

Macro Definition Documentation¶

define SD_ACMD41¶

#define SD_ACMD41 `41u`

SD_SEND_OP_COND (app)

define SD_ACMD41_RETRIES¶

#define SD_ACMD41_RETRIES `1000u`

Max ACMD41 init retries

define SD_BUSY_RETRIES¶

#define SD_BUSY_RETRIES `2000u`

Max busy wait retries

define SD_CMD0¶

#define SD_CMD0 `0u`

GO_IDLE_STATE

define SD_CMD13¶

#define SD_CMD13 `13u`

SEND_STATUS

define SD_CMD16¶

#define SD_CMD16 `16u`

SET_BLOCKLEN

define SD_CMD17¶

#define SD_CMD17 `17u`

READ_SINGLE_BLOCK

define SD_CMD24¶

#define SD_CMD24 `24u`

WRITE_BLOCK

define SD_CMD55¶

#define SD_CMD55 `55u`

APP_CMD prefix

define SD_CMD58¶

#define SD_CMD58 `58u`

READ_OCR

define SD_CMD8¶

#define SD_CMD8 `8u`

SEND_IF_COND

define SD_CMD9¶

#define SD_CMD9 `9u`

SEND_CSD

define SD_R1_ERR_MSK¶

#define SD_R1_ERR_MSK `0xFEu`

Any bit other than IDLE = error

define SD_R1_IDLE¶

#define SD_R1_IDLE `0x01u`

Card in idle state during init

define SD_R1_ILLCMD¶

#define SD_R1_ILLCMD `0x04u`

Illegal command (SDSC: no CMD8 support)

define SD_R1_POLL_RETRIES¶

#define SD_R1_POLL_RETRIES `8u`

Max R1 polling attempts

define SD_R1_READY¶

#define SD_R1_READY `0x00u`

No errors, card ready

define SD_R1_TIMEOUT¶

#define SD_R1_TIMEOUT `0xFFu`

No response from card

define SD_TOKEN_ACCEPTED¶

#define SD_TOKEN_ACCEPTED `0x05u`

Write data response: (xxx0_0101)

define SD_TOKEN_RETRIES¶

#define SD_TOKEN_RETRIES `2000u`

Max token wait retries

define SD_TOKEN_START¶

#define SD_TOKEN_START `0xFEu`

Start block for single read/write

The documentation for this class was generated from the following file src/syntropic/drivers/syn_sd.c