Expansion board v3.1, µSD pinout

  • Hello,
    we used to use Chinese board before for esp32 native C++ implementations, using wifi, LoRa and µSd.
    But Chinese board manufacturing, delay, reliability is incompatible with our products.
    That why I'm quite new in Pycom technologies, but board and scalability of Pycom product seem to match our vision,

    In short, we currently use Pycom expansion board v3.1 and LoPy4, but I did not manage to use µSD card.
    we have to reuse C++ class, C++ compilation and upload is OK.

    => Can someone tells me what pins should be used to read and write on µsd ? (SPI access to µSD ?)

  • I manage to write on µSD using SD-MMC folowing libs:

    #include "esp_vfs_fat.h"
    #include "driver/sdmmc_host.h"
    #include "driver/sdmmc_defs.h"
    #include "sdmmc_cmd.h"

    using only internal pull-up

        gpio_set_pull_mode(GPIO_NUM_2, GPIO_PULLUP_ONLY);
        gpio_set_pull_mode(GPIO_NUM_14, GPIO_PULLUP_ONLY);
        gpio_set_pull_mode(GPIO_NUM_15, GPIO_PULLUP_ONLY);
        gpio_set_pull_mode(GPIO_NUM_4, GPIO_PULLUP_ONLY);
        gpio_set_pull_mode(GPIO_NUM_12, GPIO_PULLUP_ONLY);
        gpio_set_pull_mode(GPIO_NUM_13, GPIO_PULLUP_ONLY);

  • They're earlier model board https://docs.pycom.io/datasheets/boards/expansion2/ shows P4, P8 & P23 for SD card use.

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