MMC 驱动程序¶

[English]

概述¶

SD/SDIO/MMC 驱动是一种基于 SDMMC 和 SD SPI 主机驱动的协议级驱动程序，目前已支持 SD 存储器、SDIO 卡和 eMMC 芯片。

SDMMC 主机驱动和 SD SPI 主机驱动（driver/include/driver/sdmmc_host.h）为以下功能提供 API：

发送命令至从设备
接收和发送数据
处理总线错误

初始化函数及配置函数：

如需初始化和配置 SDMMC 主机，请参阅 SDMMC 主机 API
如需初始化和配置 SD SPI 主机，请参阅 SD SPI 主机 API

本文档中所述的 SDMMC 协议层仅处理 SD 协议相关事项，例如卡初始化和数据传输命令。

协议层通过 sdmmc_host_t 结构体和主机协同工作，该结构体包含指向主机各类函数的指针。

应用示例¶

ESP-IDF storage/sd_card 目录下提供了 SDMMC 驱动与 FatFs 库组合使用的示例，演示了先初始化卡，然后使用 POSIX 和 C 库 API 向卡读写数据。请参考示例目录下 README.md 文件，查看更多详细信息。

协议层 API¶

协议层具备 sdmmc_host_t 结构体，此结构体描述了 SD/MMC 主机驱动，列出了其功能，并提供指向驱动程序函数的指针。协议层将卡信息储存于 sdmmc_card_t 结构体中。向 SD/MMC 主机发送命令时，协议层调用时需要一个 sdmmc_command_t 结构体来描述命令、参数、预期返回值和需传输的数据（如有）。

用于 SD 存储卡的 API¶

初始化主机，请调用主机驱动函数，例如 sdmmc_host_init() 和 sdmmc_host_init_slot()；
初始化卡，请调用 sdmmc_card_init()，并将参数 host （即主机驱动信息）和参数 card （指向 sdmmc_card_t 结构体的指针）传递给此函数。函数运行结束后，将会向 sdmmc_card_t 结构体填充该卡的信息；
读取或写入卡的扇区，请分别调用 sdmmc_read_sectors() 和 sdmmc_write_sectors()，并将参数 card （指向卡信息结构的指针）传递给函数；
如果不再使用该卡，请调用主机驱动函数，例如 sdmmc_host_deinit()，以禁用主机外设，并释放驱动程序分配的资源。

用于 eMMC 芯片的 API¶

从协议层的角度而言，eMMC 存储芯片与 SD 存储卡相同。尽管 eMMC 是芯片，不具备卡的外形，但由于协议相似 (sdmmc_card_t, sdmmc_card_init)，用于 SD 卡的一些概念同样适用于 eMMC 芯片。注意，eMMC 芯片不可通过 SPI 使用，因此它与 SD API 主机驱动不兼容。

如需初始化 eMMC 内存并执行读/写操作，请参照上一章节 SD 卡操作步骤。

用于 SDIO 卡的 API¶

SDIO 卡初始化和检测过程与 SD 存储卡相同，唯一的区别是 SDIO 模式下数据传输命令不同。

在卡初始化和卡检测（通过运行 sdmmc_card_init()）期间，驱动仅配置 SDIO 卡如下寄存器：

I/O 中止 (0x06) 寄存器：在该寄存器中设置 RES 位可重置卡的 I/O 部分；
总线接口控制 (0x07) 寄存器：如果主机和插槽配置中启用 4 线模式，则驱动程序会尝试在该寄存器中设置总线宽度字段。如果字段设置成功，则从机支持 4 线模式，主机也切换至 4 线模式；
高速（0x13）寄存器：如果主机配置中启用高速模式，则会在该寄存器中设置 SHS 位。

注意，驱动程序不会在 (1) I/O 使能寄存器和 Int 使能寄存器，及 (2) I/O 块大小中，设置任何位。应用程序可通过调用 sdmmc_io_write_byte() 来设置相关位。

如需设置卡配置或传输数据，请根据您的具体情况选择下表中的函数：

操作	读函数	写函数
使用 IO_RW_DIRECT (CMD52) 读写单个字节。	`sdmmc_io_read_byte()`	`sdmmc_io_write_byte()`
使用 IO_RW_EXTENDED (CMD53) 的字节模式读写多个字节。	`sdmmc_io_read_bytes()`	`sdmmc_io_write_bytes()`
块模式下，使用 IO_RW_EXTENDED (CMD53) 读写数据块。	`sdmmc_io_read_blocks()`	`sdmmc_io_write_blocks()`

使用 sdmmc_io_enable_int() 函数，应用程序可启用 SDIO 中断。

在单线模式下使用 SDIO 时，还需要连接 D1 线来启用 SDIO 中断。

如果您需要应用程序保持等待直至发生 SDIO 中断，请使用 sdmmc_io_wait_int() 函数。

复合卡（存储 + SDIO）¶

该驱动程序不支持 SDIO 复合卡，复合卡会被视为 SDIO 卡。

线程安全¶

多数应用程序仅需在一个任务中使用协议层。因此，协议层在 sdmmc_card_t 结构体或在访问 SDMMC 或 SD SPI 主机驱动程序时不使用任何类型的锁。这种锁通常在较高层级实现，例如文件系统驱动程序。

API 参考¶

Header File¶

sdmmc/include/sdmmc_cmd.h

Functions¶

esp_err_t sdmmc_card_init(const sdmmc_host_t *host, sdmmc_card_t *out_card)¶

Probe and initialize SD/MMC card using given host

Note

Only SD cards (SDSC and SDHC/SDXC) are supported now. Support for MMC/eMMC cards will be added later.

Return

ESP_OK on success
One of the error codes from SDMMC host controller

Parameters

host: pointer to structure defining host controller
out_card: pointer to structure which will receive information about the card when the function completes

void sdmmc_card_print_info(FILE *stream, const sdmmc_card_t *card)¶

Print information about the card to a stream.

Parameters

stream: stream obtained using fopen or fdopen
card: card information structure initialized using sdmmc_card_init

esp_err_t sdmmc_write_sectors(sdmmc_card_t *card, const void *src, size_t start_sector, size_t sector_count)¶

Write given number of sectors to SD/MMC card

Return

ESP_OK on success
One of the error codes from SDMMC host controller

Parameters

card: pointer to card information structure previously initialized using sdmmc_card_init
src: pointer to data buffer to read data from; data size must be equal to sector_count * card->csd.sector_size
start_sector: sector where to start writing
sector_count: number of sectors to write

esp_err_t sdmmc_read_sectors(sdmmc_card_t *card, void *dst, size_t start_sector, size_t sector_count)¶

Write given number of sectors to SD/MMC card

Return

ESP_OK on success
One of the error codes from SDMMC host controller

Parameters

card: pointer to card information structure previously initialized using sdmmc_card_init
dst: pointer to data buffer to write into; buffer size must be at least sector_count * card->csd.sector_size
start_sector: sector where to start reading
sector_count: number of sectors to read

esp_err_t sdmmc_io_read_byte(sdmmc_card_t *card, uint32_t function, uint32_t reg, uint8_t *out_byte)¶

Read one byte from an SDIO card using IO_RW_DIRECT (CMD52)

Return

ESP_OK on success
One of the error codes from SDMMC host controller

Parameters

card: pointer to card information structure previously initialized using sdmmc_card_init
function: IO function number
reg: byte address within IO function
[out] out_byte: output, receives the value read from the card

esp_err_t sdmmc_io_write_byte(sdmmc_card_t *card, uint32_t function, uint32_t reg, uint8_t in_byte, uint8_t *out_byte)¶

Write one byte to an SDIO card using IO_RW_DIRECT (CMD52)

Return

ESP_OK on success
One of the error codes from SDMMC host controller

Parameters

card: pointer to card information structure previously initialized using sdmmc_card_init
function: IO function number
reg: byte address within IO function
in_byte: value to be written
[out] out_byte: if not NULL, receives new byte value read from the card (read-after-write).

esp_err_t sdmmc_io_read_bytes(sdmmc_card_t *card, uint32_t function, uint32_t addr, void *dst, size_t size)¶

Read multiple bytes from an SDIO card using IO_RW_EXTENDED (CMD53)

This function performs read operation using CMD53 in byte mode. For block mode, see sdmmc_io_read_blocks.

Return

ESP_OK on success
ESP_ERR_INVALID_SIZE if size exceeds 512 bytes
One of the error codes from SDMMC host controller

Parameters

card: pointer to card information structure previously initialized using sdmmc_card_init
function: IO function number
addr: byte address within IO function where reading starts
dst: buffer which receives the data read from card
size: number of bytes to read

esp_err_t sdmmc_io_write_bytes(sdmmc_card_t *card, uint32_t function, uint32_t addr, const void *src, size_t size)¶

Write multiple bytes to an SDIO card using IO_RW_EXTENDED (CMD53)

This function performs write operation using CMD53 in byte mode. For block mode, see sdmmc_io_write_blocks.

Return

ESP_OK on success
ESP_ERR_INVALID_SIZE if size exceeds 512 bytes
One of the error codes from SDMMC host controller

Parameters

card: pointer to card information structure previously initialized using sdmmc_card_init
function: IO function number
addr: byte address within IO function where writing starts
src: data to be written
size: number of bytes to write

esp_err_t sdmmc_io_read_blocks(sdmmc_card_t *card, uint32_t function, uint32_t addr, void *dst, size_t size)¶

Read blocks of data from an SDIO card using IO_RW_EXTENDED (CMD53)

This function performs read operation using CMD53 in block mode. For byte mode, see sdmmc_io_read_bytes.

Return

ESP_OK on success
ESP_ERR_INVALID_SIZE if size is not divisible by 512 bytes
One of the error codes from SDMMC host controller

Parameters

card: pointer to card information structure previously initialized using sdmmc_card_init
function: IO function number
addr: byte address within IO function where writing starts
dst: buffer which receives the data read from card
size: number of bytes to read, must be divisible by the card block size.

esp_err_t sdmmc_io_write_blocks(sdmmc_card_t *card, uint32_t function, uint32_t addr, const void *src, size_t size)¶

Write blocks of data to an SDIO card using IO_RW_EXTENDED (CMD53)

This function performs write operation using CMD53 in block mode. For byte mode, see sdmmc_io_write_bytes.

Return

ESP_OK on success
ESP_ERR_INVALID_SIZE if size is not divisible by 512 bytes
One of the error codes from SDMMC host controller

Parameters

card: pointer to card information structure previously initialized using sdmmc_card_init
function: IO function number
addr: byte address within IO function where writing starts
src: data to be written
size: number of bytes to read, must be divisible by the card block size.

esp_err_t sdmmc_io_enable_int(sdmmc_card_t *card)¶

Enable SDIO interrupt in the SDMMC host

Return

ESP_OK on success
ESP_ERR_NOT_SUPPORTED if the host controller does not support IO interrupts

Parameters

card: pointer to card information structure previously initialized using sdmmc_card_init

esp_err_t sdmmc_io_wait_int(sdmmc_card_t *card, TickType_t timeout_ticks)¶

Block until an SDIO interrupt is received

Slave uses D1 line to signal interrupt condition to the host. This function can be used to wait for the interrupt.

Return

ESP_OK if the interrupt is received
ESP_ERR_NOT_SUPPORTED if the host controller does not support IO interrupts
ESP_ERR_TIMEOUT if the interrupt does not happen in timeout_ticks

Parameters

card: pointer to card information structure previously initialized using sdmmc_card_init
timeout_ticks: time to wait for the interrupt, in RTOS ticks

esp_err_t sdmmc_io_get_cis_data(sdmmc_card_t *card, uint8_t *out_buffer, size_t buffer_size, size_t *inout_cis_size)¶

Get the data of CIS region of a SDIO card.

You may provide a buffer not sufficient to store all the CIS data. In this case, this functions store as much data into your buffer as possible. Also, this function will try to get and return the size required for you.

Return

ESP_OK: on success
ESP_ERR_INVALID_RESPONSE: if the card does not (correctly) support CIS.
ESP_ERR_INVALID_SIZE: CIS_CODE_END found, but buffer_size is less than required size, which is stored in the inout_cis_size then.
ESP_ERR_NOT_FOUND: if the CIS_CODE_END not found. Increase input value of inout_cis_size or set it to 0, if you still want to search for the end; output value of inout_cis_size is invalid in this case.
and other error code return from sdmmc_io_read_bytes

Parameters

card: pointer to card information structure previously initialized using sdmmc_card_init
out_buffer: Output buffer of the CIS data
buffer_size: Size of the buffer.
inout_cis_size: Mandatory, pointer to a size, input and output.
- input: Limitation of maximum searching range, should be 0 or larger than buffer_size. The function searches for CIS_CODE_END until this range. Set to 0 to search infinitely.
- output: The size required to store all the CIS data, if CIS_CODE_END is found.

esp_err_t sdmmc_io_print_cis_info(uint8_t *buffer, size_t buffer_size, FILE *fp)¶

Parse and print the CIS information of a SDIO card.

Note

Not all the CIS codes and all kinds of tuples are supported. If you see some unresolved code, you can add the parsing of these code in sdmmc_io.c and contribute to the IDF through the Github repository.

         using sdmmc_card_init

Return

ESP_OK: on success
ESP_ERR_NOT_SUPPORTED: if the value from the card is not supported to be parsed.
ESP_ERR_INVALID_SIZE: if the CIS size fields are not correct.

Parameters

buffer: Buffer to parse
buffer_size: Size of the buffer.
fp: File pointer to print to, set to NULL to print to stdout.

Header File¶

driver/include/driver/sdmmc_types.h

Structures¶

struct sdmmc_csd_t¶

Decoded values from SD card Card Specific Data register

Public Members

int csd_ver¶: CSD structure format

int mmc_ver¶: MMC version (for CID format)

int capacity¶: total number of sectors

int sector_size¶: sector size in bytes

int read_block_len¶: block length for reads

int card_command_class¶: Card Command Class for SD

int tr_speed¶: Max transfer speed

struct sdmmc_cid_t¶

Decoded values from SD card Card IDentification register

Public Members

int mfg_id¶: manufacturer identification number

int oem_id¶: OEM/product identification number

char name[8]¶: product name (MMC v1 has the longest)

int revision¶: product revision

int serial¶: product serial number

int date¶: manufacturing date

struct sdmmc_scr_t¶

Decoded values from SD Configuration Register

Public Members

int sd_spec¶: SD Physical layer specification version, reported by card

int bus_width¶: bus widths supported by card: BIT(0) — 1-bit bus, BIT(2) — 4-bit bus

struct sdmmc_ext_csd_t¶

Decoded values of Extended Card Specific Data

Public Members

uint8_t power_class¶: Power class used by the card

struct sdmmc_switch_func_rsp_t¶

SD SWITCH_FUNC response buffer

Public Members

uint32_t data[512 / 8 / sizeof(uint32_t)]¶: response data

struct sdmmc_command_t¶

SD/MMC command information

Public Members

uint32_t opcode¶: SD or MMC command index

uint32_t arg¶: SD/MMC command argument

sdmmc_response_t response¶: response buffer

void *data¶: buffer to send or read into

size_t datalen¶: length of data buffer

size_t blklen¶: block length

int flags¶: see below

esp_err_t error¶: error returned from transfer

int timeout_ms¶: response timeout, in milliseconds

struct sdmmc_host_t¶

SD/MMC Host description

This structure defines properties of SD/MMC host and functions of SD/MMC host which can be used by upper layers.

Public Members

uint32_t flags¶: flags defining host properties

int slot¶: slot number, to be passed to host functions

int max_freq_khz¶: max frequency supported by the host

float io_voltage¶: I/O voltage used by the controller (voltage switching is not supported)

esp_err_t (*init)(void)¶: Host function to initialize the driver

esp_err_t (*set_bus_width)(int slot, size_t width)¶: host function to set bus width

size_t (*get_bus_width)(int slot)¶: host function to get bus width

esp_err_t (*set_bus_ddr_mode)(int slot, bool ddr_enable)¶: host function to set DDR mode

esp_err_t (*set_card_clk)(int slot, uint32_t freq_khz)¶: host function to set card clock frequency

esp_err_t (*do_transaction)(int slot, sdmmc_command_t *cmdinfo)¶: host function to do a transaction

esp_err_t (*deinit)(void)¶: host function to deinitialize the driver

esp_err_t (*io_int_enable)(int slot)¶: Host function to enable SDIO interrupt line

esp_err_t (*io_int_wait)(int slot, TickType_t timeout_ticks)¶: Host function to wait for SDIO interrupt line to be active

int command_timeout_ms¶: timeout, in milliseconds, of a single command. Set to 0 to use the default value.

struct sdmmc_card_t¶

SD/MMC card information structure

Public Members

sdmmc_host_t host¶: Host with which the card is associated

uint32_t ocr¶: OCR (Operation Conditions Register) value

sdmmc_cid_t cid¶: decoded CID (Card IDentification) register value

sdmmc_response_t raw_cid¶: raw CID of MMC card to be decoded after the CSD is fetched in the data transfer mode

sdmmc_csd_t csd¶: decoded CSD (Card-Specific Data) register value

sdmmc_scr_t scr¶: decoded SCR (SD card Configuration Register) value

sdmmc_ext_csd_t ext_csd¶: decoded EXT_CSD (Extended Card Specific Data) register value

uint16_t rca¶: RCA (Relative Card Address)

uint16_t max_freq_khz¶: Maximum frequency, in kHz, supported by the card

uint32_t is_mem : 1¶: Bit indicates if the card is a memory card

uint32_t is_sdio : 1¶: Bit indicates if the card is an IO card

uint32_t is_mmc : 1¶: Bit indicates if the card is MMC

uint32_t num_io_functions : 3¶: If is_sdio is 1, contains the number of IO functions on the card

uint32_t log_bus_width : 2¶: log2(bus width supported by card)

uint32_t is_ddr : 1¶: Card supports DDR mode

uint32_t reserved : 23¶: Reserved for future expansion

Macros¶

SDMMC_HOST_FLAG_1BIT¶: host supports 1-line SD and MMC protocol

SDMMC_HOST_FLAG_4BIT¶: host supports 4-line SD and MMC protocol

SDMMC_HOST_FLAG_8BIT¶: host supports 8-line MMC protocol

SDMMC_HOST_FLAG_SPI¶: host supports SPI protocol

SDMMC_HOST_FLAG_DDR¶: host supports DDR mode for SD/MMC

SDMMC_FREQ_DEFAULT¶: SD/MMC Default speed (limited by clock divider)

SDMMC_FREQ_HIGHSPEED¶: SD High speed (limited by clock divider)

SDMMC_FREQ_PROBING¶: SD/MMC probing speed

SDMMC_FREQ_52M¶: MMC 52MHz speed

SDMMC_FREQ_26M¶: MMC 26MHz speed

Type Definitions¶

typedef uint32_t sdmmc_response_t[4]¶: SD/MMC command response buffer

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