Adafruit microSD Card BFF Add-On for QT Py and Xiao

Our QT Py boards are a great way to make very small microcontroller projects that pack a ton of power – and now we have a way for you to add a ton of storage, for reading and writing, with a micro SD card slot that can fit on the back of your miniature dev board. It uses the three SPI pins plus one chip select pin to access megs or gigs of data.

We call this the Adafruit microSD BFF – a ‘Best Friend Forever’. When you were a kid you may have learned about the ‘buddy’ system, well this product is kinda like that! A board that will watch your QT Py’s back and give it more capabilities.

This PCB is designed to fit onto the back of any QT Py or Xiao board, it can be soldered into place or use pin and socket headers to make it removable. Onboard is a slim, high quality Molex push-pull micro SD card socket. Since the QT Py is already 3V, no level shifter or regulator is required. We’re using SPI mode to interface, use the MOSI/MISO/SCK pins plus one other chip select pin. The default is TX but there are some solder jumpers you can use to select RX, A0 or A1.

We include some headers that you can solder to your QT Py. You can also pick up an Itsy Bitsy short female header kit to make it removable but compact, you’ll just need to trim down the headers to 7 pins long.

• Comes as an assembled and tested PCB
• For any QT Py or Xiao boards
• Use any micro SD card that supports SPI mode with one CS pin.
• Any Arduino / CircuitPython / MicroPython library can be used to talk to the card just like a normal SD card breakout!

microSD card and QT Py are not included.

Resources

• Primary Guide: Adafruit microSD Card BFF