DIY MIDI Footswitch

Author: Przemysław Kojs
License: GNU v3 Public License
Version: v1.0 (Oct. 17, 2024)

Introduction

This project was inspired by the lack of a 16-button MIDI footswitch available on the internet, which I needed for a handmade electronic pipe organ console. I already had some background in Arduino programming and know C/C++ well, so I decided to create one myself. The design took several days, but coding only took a few hours. Since we are on GitHub, I will focus solely on the Arduino and MIDI-related aspects of the project.

Overview

The project uses the standard Arduino MIDIUSB library. The code is designed for 16 buttons, requiring 16 pins. In my case, I used digital pins 2-6, 8-10, 12, 13, and all analog pins (A0-A5). If you need fewer pins, you can modify the necessary variables. All array lengths must match and be equal to the NUM_OF_BUTTONS constant. Remember to also adjust the NUM_OF_PUSH_BUTTONS constant, ensuring its value is less than or equal to NUM_OF_BUTTONS.

Most of the pins, once connected to the buttons, act as toggle switches. However, pins A2-A5 (buttons 12-15) function as push buttons. This configuration is specific to my needs and is available in the ButtonSwitch.ino file. In contrast, in the Switch.ino file, all pins behave like toggle buttons.

Which one should I choose?
If you need something like a guitar pedalboard—where all buttons are toggle buttons—use the Switch.ino file. If you need some buttons to behave as push buttons, use the ButtonSwitch.ino file.

The number of push buttons can be changed by modifying the NUM_OF_PUSH_BUTTONS constant, located at the beginning of the file (line 10).

MIDI notes used range from 111 to 126. If you want a specific button to trigger an action, assign it to a MIDI note. I suggest creating a reference scheme for which button is connected to which pin and which MIDI note, as you may want to make changes in the future.

Electronics Used

1. Arduino Leonardo (with a Micro-USB cable). Alternatives include the Zero, Due, 101, and Micro.
2. Wires
3. 16 arcade push buttons
   Important: LEDs in the buttons are non-functional due to a lack of available pins and wires.

Pin Mappings

Pins are arranged in ascending order, corresponding to the MIDI notes used. You can modify this arrangement if necessary, but duplicate pin assignments may cause issues with the code.

Table 1. Pin to MIDI Note Mappings.

Pin	MIDI Note
2	111
3	112
4	113
5	114
6	115
8	116
9	117
10	118
12	119
13	120
A0	121
A1	122
A2	123
A3	124
A4	125
A5	126

Other Information

Table 2. MIDI Information.

MIDI Info	Value
Velocity	127
Channel	0

Note: Multiple channels are not supported. If you need this functionality, you will need to modify the code yourself.

Table 3. Default Settings.

Setting	Value
Button Debounce Time [ms]	50
Number of Toggle Buttons	12
Number of Push Buttons	4
Total Number of Buttons	16

You can change these values, but remember to adjust all related arrays and variables accordingly. I do not recommend setting the Button Debounce Time lower than 50 ms.