MIDI Mod Wheel Using an Expression Pedal

A little while back, a friend asked me to help him with a keyboard problem he was having. He has one of those super cool Nord keyboards and the thing works great; except for the mod wheel. He's not sure how it happened but the thing just doesn't work. He also doesn't consider it important enough to open up the whole keyboard to see if it's fixable. So, he asked me to make this little MIDI converter box for him. He already has a pedalboard with an unused expression pedal on it so this seemed like a great option. Conceptually, this box is quite simple. Use some sort of microcontroller to take an analog reading of the foot pedal and convert that to a MIDI CC command to be sent to the Nord. From that information, I created this. Bottom left is a TRS 1/4" jack I got off Amazon. It cost more than it should have but man is Prime shipping fantastic. Bottom right is the MIDI jack; from the same batch as my previous MIDI controller build. The brain of the operati...