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STM32 SD library for Arduino

With an STM32 board with SD card slot availability, this library enables reading and writing on SD card using SD card slot of a STM32 board (NUCLEO, DISCOVERY, ...). This library is for SD card slots connected to the SDIO-/SDMMC-hardware of the processor. For slots connected to SPI-hardware use the standard Arduino SD library.

This library follow Arduino API.

For more information about it, please visit: http://www.arduino.cc/en/Reference/SD

Dependency

This library is based on FatFs, a generic FAT file system module for small embedded systems. http://elm-chan.org/fsw/ff

The FatFs has been ported as Arduino library here. The STM32SD library depends on it.

Configuration

FatFs

The FatFs has several user defined options, which is specified from within the ffconf.h file.

This library provides a default user defined options file named ffconf_default.h.

User can provide his own defined options by adding his configuration in a file named ffconf_custom.h at sketch level or in variant folder.

SD

Some default definitions can be overridden using:

SDIO/SDMMC pins definition

Important

Since STM32 core v2.6.0, the PinMap_SD[] array defined in the PeripheralPins*.c has been split per signals:

PinMap_SD_CK[]
PinMap_SD_DATA0[]
PinMap_SD_DATA1[]
PinMap_SD_DATA2[]
PinMap_SD_DATA3[]
PinMap_SD_DATA4[]
PinMap_SD_DATA5[]
PinMap_SD_DATA6[]
PinMap_SD_DATA7[]
/* Only for SDMMC */
PinMap_SD_CKIN[]
PinMap_SD_CDIR[]
PinMap_SD_D0DIR[]
PinMap_SD_D123DIR[]

This allows to define the SDIO/SDMMC pins to use instead of using all the pins defined in the old array. By default, if no pins are explicitly defined, the first one from each array is used.

  • To redefine the default one, use the following macros:

    • SDX_D0

    • SDX_D1

    • SDX_D2

    • SDX_D3

    • SDX_CMD

    • SDX_CK

    • Only for SDMMC:

      • SDX_CKIN
      • SDX_CDIR
      • SDX_D0DIR
      • SDX_D123DIR

  • or redefine the default one before call of begin() of SDClass or init() of Sd2Card, using the following methods:

    • setDx(uint32_t data0, uint32_t data1, uint32_t data2, uint32_t data3)

    [!NOTE] If SD_BUS_WIDE_1B is used only data0 is needed.

    • setCK(uint32_t ck)

    • setCK(PinName ck)

    • setCMD(uint32_t cmd)

    • setCMD(PinName cmd)

    • Only for SDMMC:

      • setCKIN(uint32_t ckin)
      • setCKIN(PinName ckin)
      • setCDIR(uint32_t cdir)
      • setCDIR(PinName cdir)
      • setDxDIR(uint32_t d0dir, uint32_t d123dir)
      • setDxDIR(PinName d0dir, PinName d123dir)

    Code snippet:

  Sd2Card card;
  card.setDx(PE12, PE13, PE14, PE15);
  card.setCMD(PB_14); // using PinName
  card.setCK(PB15);
  card.init();

or

  SD.setDx(PE12, PE13, PE14, PE15);
  SD.setCMD(PB14);
  SD.setCK(PB_15); // using PinName
  SD.begin();

SD configurations

  • SD_INSTANCE: some STM32 can have 2 SD peripherals SDMMC1 and SDMMC2, note that this library can managed only one peripheral

    • SDIO or SDMMC1 (default)
    • SDMMC2

  • SD_HW_FLOW_CTRL: specifies whether the SDMMC hardware flow control is enabled or disabled

    • SD_HW_FLOW_CTRL_ENABLE
    • SD_HW_FLOW_CTRL_DISABLE (default)

  • SD_BUS_WIDE: specifies the SDMMC bus width

    • SD_BUS_WIDE_1B
    • SD_BUS_WIDE_4B (default)

  • SD_CLK_DIV: specifies the clock frequency of the SDMMC controller (0-255)

    • SDIO_TRANSFER_CLK_DIV (default) for SDIO
    • SDMMC_TRANSFER_CLK_DIV or SDMMC_NSpeed_CLK_DIV (default) for SDMMC

SD Transceiver

  • To specifies whether external Transceiver is present and enabled (Available only on some STM32) add:

    #define USE_SD_TRANSCEIVER 1

  • Then define pins:

    • SD_TRANSCEIVER_EN pin number to enable the level shifter
    • SD_TRANSCEIVER_SEL pin number for voltage selection

SD detect and timeout

  • SD_DETECT_PIN pin number
  • SD_DETECT_LEVEL default LOW
  • SD_DATATIMEOUT constant for Read/Write block