Did you know you can use a QT Py RP2040 as a USB to Serial MIDI converter? The QT Py RP2040, running CircuitPython code, receives MIDI messages over USB and then sends the messages out over serial UART. You can build small add-on boards, or friends, for TRS-A, TRS-B and DIN-5 MIDI out circuits that plug directly into the QT Py RP2040.

This concept was inspired by Sandy Macdonald on Twitter. It makes for a compact and simple solution for interfacing hardware MIDI devices with USB.

The MIDI friend breakouts plug directly into a QT Py RP2040 with socket headers.

Versions for TRS-A, TRS-B and DIN-5 MIDI connections are shown in this guide. You can choose which one to build depending on your hardware MIDI device.


If you aren't sure which type of TRS connection your TRS MIDI device uses, you can search for it on minimidi.world to see if it uses TRS-A or TRS-B. TRS-A is currently the MIDI standard, but many devices out there have TRS-B sockets. The difference is that the 3V and TX serial connections are swapped on the audio jack.

Prerequisite Guides and Resources


Video of hand holding a QT Py PCB in their hand. An LED glows rainbow colors.
What a cutie pie! Or is it... a QT Py? This diminutive dev board comes with one of our new favorite chip, the RP2040. It's been made famous in the new
Breadboard-Friendly 3.5mm Stereo Headphone Jack
Pipe audio in or out of your project with this very handy breadboard-friendly audio jack. It's a stereo jack with disconnect-switches on Left and Right channels as well as a center...
Breadboard-friendly MIDI Jack
To celebrate the 30th Anniversary of the invention of MIDI we're carrying these handy 5-pin MIDI jacks. They're what you see on the back of nearly every synthesizer and drum...
Angled shot of single Bakelite Universal Perfboard Plate.
Make your next project as you imagine it with prototyping perfboards that can easily be cut with scissors like these Bakelite Universal Perfboard Plates!We...
Very strong looking scissors with comfy grip
Save your scissors! Instead of using your nice shears (and dulling them) or wire cutters (not right for the job) - use these super scissors. They're meant for engineering/maker...
Angled shot of coiled pink and purple USB cable with USB A and USB C connectors.
This cable is not only super-fashionable, with a woven pink and purple Blinka-like pattern, it's also made for USB C for our modernized breakout boards, Feathers, and...
1 x 10Ω Resistor
10Ω resistor for TX connection
1 x 30Ω Resistor
30Ω resistor for 3.3V connection

This guide was first published on Apr 26, 2022. It was last updated on Jul 13, 2024.

This page (Overview) was last updated on Mar 08, 2024.

Text editor powered by tinymce.