Sometimes getting a keyboard player to play pads during shows may be difficult... we overcome this problem by building a pad pedal that is used to send MIDI notes to a PC, which in turns reproduces the sounds by means of a VST/VST3 plugin either standalone or inside a DAW as Ableton or the like.

The Pad Pedal uses an Arduino UNO to send the MIDI notes - and optionally volume and modulation controls - to a PC via USB. Each pushbutton sends a different note from C to B, and the note keeps playing until the same button is pressed. If another button is pressed, then the note stops and the new note starts playing.

By default, each note plays together with its 5th., e.g. D+A or E+B. This way, it sounds well both with minor and major chords. This can be changed by pressing 2 buttons together: (F+G) starts sounding only the base note, (G+A) starts playing the note plus the 5th, and (A+B) starts playing the note plus the 5th and the 8ve.

To change octave, (C+D) or (D+E) can be pressed together. Each time they are pressed, the sounds goes down or up one octave, respectively.

For monitoring reasons, the LED turns on while a sound is playing.

Potentiometers can be used to adjust volume and modulation, they are off by default and can be enabled by changing the constants at the beginning of the code from "false" to "true".

The circuit is very simple, the tough part is to install and run all the software to make it work on a PC. You'll need:

- Loop MIDI port. I use LoopMIDI by Tobias Erichsen. Install it and create a port by clicking on the "+" sign.

- Serial to MIDI software. I am using hairless-midiserial. It is missing in GitHUB so I downloaded it from the Web Archive (Windows version - there are Mac and Linux versions too). Just unzip and run it, select the Arduino USB serial port at left and "loopMIDI" at MIDI Out.

- A virtual instrument to play. There are lots of free virtual instruments ( VST or VST3 ) in the web. Some are standalone, some others require a DAW as Reaper, Ableton Live or other - in this case you have to create a MIDI track with some instrument in it, select the loopMIDI input, and set to record mode. In a standalone VST, select your MIDI input to be loopMIDI .

NOTE: before downloading the Arduino program, set the hairless-midiserial input to "not connected" (otherwise you will get an error). Then set it to the COM port again.

Enjoy!

PS. you can watch a video of the pedal working at YouTube: https://www.youtube.com/watch?v=Q-MtA13by1o

EXPANDED TECHNICAL DETAILS

Digital MIDI Foot-Controller

Pad Pedal transforms any physical pedal (sustain, expression, or DIY) into a versatile USB MIDI controller for DAW (Digital Audio Workstation) software.

• Hairless MIDI-Serial Bridge Integration: The Arduino sends standard MIDI packets over the serial link. A software bridge on the PC translates this into a Virtual MIDI Port that any VST/VST3 plugin can recognize.
• Analog Sustain Curve: Captures the analog values from a potentiometer-based pedal, providing a smooth 0-127 "Control Change" ($CC$) signal for expressive volume or filter sweeps.

Hardware

• loopMIDI Virtual Porting: Uses loopMIDI on the PC side to route the Arduino signals to professional music software without the need for a dedicated MIDI-to-USB hardware interface.