Turn your feather into a songbird with this musically activated FeatherWing that adds MIDI input and output sockets to almost any spring. You will receive both input and output DIN 5 MIDI sockets, a 3V optical isolator, so you can connect MIDI to 3.3V logic/power microcontrollers, and two flashing indicator LEDs under the sockets to help you know when data is being sent and received. For those who have converted from DIN-5 sockets to "TRS MIDI A" 3.5mm jacks, Adafruit have left points to 3.5mm stereo jack (optional and not included).
It uses the RX and TX serial hardware pins to send/receive data - you need to set them to 31250 baud in your programming language and then send / receive MIDI package data.
As they have used UART this works with all springs except for those with USB serial converters that use the UART pins. This now means that the ESP8266 Huzzah Feather, 328p Feather and nRF52 Feather will not work because they use UART hardware for programming. All other native USB native springs work perfectly.