sdcardio is an SPI interface SD card library in CircuitPython 6.0 that is optimized in C to be much faster than the original adafruit_sdcard library. Some much smaller/older boards don't have enough memory for this module, in which case you will have to use adafruit_sdcard

Ready to do a little wiring?  Almost any Adafruit CircuitPython board will connect to the MicroSD Breakout Board using SPI. The following is an example using the Itsy BItsy M4 express.

  • Board 3V to breakout 3V via supply rail
  • Board GND to breakout GND via supply rail
  • Board MI (or MISO) to breakout SO
  • Board MO (or MOSI) to breakout SI
  • Board SCK to breakout CLK
  • Board D10 to breakout CS

The example below uses D10, but you can use any available digital pin instead. Change the code below to use the pin you selected instead of board.D10.

The ItsyBitsy and the MicroSD breakout are a great way to have SD card storage in a small footprint, but these instructions will work with just about any Adafruit Feather too. Just follow the fritzing diagram and then put the following in

import board
import busio
import sdcardio
import storage

spi = board.SPI()
cs = board.D10     # Use the pin you wired to the breakout CS

sdcard = sdcardio.SDCard(spi, cs)
vfs = storage.VfsFat(sdcard)
storage.mount(vfs, "/sd")

The default communication rate is 8MHz, which works with most SD cards. A higher or lower rate can be supplied with sdcardio.SDCard(spi, cs, baudrate=...) but the limitation depends on

  • the specific microcontroller's SPI interface
  • the specific SD card's operating characteristics
  • the wiring, especially if a breadboard or jumper wires are involved
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This guide was first published on Jul 31, 2020. It was last updated on Nov 29, 2023.

This page (ItsyBitsy M4 Express + Breakout) was last updated on Jul 24, 2020.

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