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microSD Card Example


The microSD Card Example demonstrates the use of a microSD memory card using the SD Card library and the FatFs file system library.

The example initializes the card and performs basic operations like mounting the FAT volume, writing and reading the example file.

The microSD Card is connected to the nRF52840 chip over a SPI bus. The table below shows the connections of each pin of the microSD Card:

microSD Card Pin nRF52840 Pin
nCS P0_07
SCLK P0_11
MOSI P0_12
MISO P1_08

Before you start coding, the Python Interpreter should be installed on the nRF52840 M.2 module correctly:

Run the code

Run the microSD Card Example by performing the following steps:

  1. Power down the board

  2. Insert a FAT formatted microSD card into the microSD slot

  3. Connect the Module USB port to your PC as shown in the figure below. A disk drive called CIRCUITPY should be automatically detected by the computer:

  4. Open the file on your CIRCUITPY drive, then copy and paste the following code. Your code will run as soon as the file is done saving.

    # SD card usage
    import board
    import digitalio
    import displayio
    import sdcard
    import storage
    spi = board.SPI()
    cs = digitalio.DigitalInOut(board.P7)
    sd = sdcard.SDCard(spi, cs)
    vfs = storage.VfsFat(sd)
    storage.mount(vfs, "/sd")
    print("microSD Card mounted.")
    # write to sd card
    print("Writing to file /sd/test.txt ...")
    with open("/sd/test.txt", "w") as f:
        f.write("This is the written string.\n")
    # read from sd card
    print("Reading from file /sd/test.txt ...")
    with open("/sd/test.txt", "r") as f:
        data =
  5. Run a terminal application like PuTTY or screen:

    screen /dev/cu.usbmodem14102 115200
  6. Save the code and observe the output of the terminal:

Create an Issue

Interested in contributing to this project? Want to report a bug? Feel free to click here: