Adafruit I2S Amplifier 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 an I2S 3 Watt amplifier, for high-quality audio playback, that can fit on the back of your miniature dev board. It uses just three GPIO pins that do not intersect with the I2C/UART or SPI port.

We call this the Adafruit I2S Amp 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 MAX98357 audio amplifier and picoblade-compatible connector for plugging in a 4 or 8-ohm speaker. We use A0 for the audio data, A1 for the word select clock, and A2 for the bit clock. This pinout will work with ESP32 series, nRF52840 and RP2040 chipset boards. It won’t work with the ATSAMD21 ‘original ‘QT Py because those pins on the SAMD21 are not I2S capable. However, you could cut and rewire the traces to connect to the I2S pads if desired – personally, we recommend just upgrading to an RP2040 QT Py instead.

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
• Contains a MAX98357 3 Watt audio amplifier pre-configured for ‘stereo’ mix output and 9 dB gain which will work great for any project.
• Connect to the speaker output with a picoblade-compatible 2-pin cable. We recommend this 3W 4-ohm speaker
• There are various Arduino / CircuitPython / MicroPython libraries that can be used to talk to the I2S amplifier.

Speaker and QT Py are NOT included.

Resources

• Product Wiki