Sometimes a piece of gear really needs a few MIDI control buttons strategically located. Now you can stick them on where needed.

• SparkFun Pro Micro or Arduino Micro

These boards are convenient because the pin arrangment includes a section with a ground pin with 4 digital pins. The cable from the keypad can be plugged directly into that section of the board. Other boards with the ATMEGA32U4 chip should work but might require extra work to wire the keypad to the board.

The photo shows a Pro Micro clone board. Right angle headers are used to keep the assembly as flat as possible. After soldering, the pins on the back were cut flush with the board.

• Generic 4 button membrane keypad

Stick on where needed. But it may not be easy to remove so think twice before sticking. Peel off the white paper on the back to uncover the adhesive. The Arduino board can be stuck on using double-sided foam tape. This stuff is also hard to remove.

Install the bounce2, MIDIUSB, and MIDI libraries using the Arduino IDE library manager.

The sketch can be customized to send MIDI messages.

NOTE: System Exclusve arrays should be stored in program memory using the PROGMEM attribute then sent using the USBSystemExclusive_P function. If not, RAM will be quickly used up.

Twelve button MIDI USB controller.

https://github.com/gdsports/buttons12

101 button MIDI DIN controller.

https://github.com/gdsports/USBHIDKbd2MIDI