The velocity data of the notes themselves is not important in organs as it would be in say, a piano-type instrument. I didn't need this because the clonewheel organ I use (as well as pretty much any other) has a dedicated input for a CV pedal, which controls the universal volume of the entire instrument (both manuals as well as bass pedals simultaneously). Royce wrote the code in for a volume (or 'velocity') pedal, which I removed. And in doing so, I then reversed the logic to properly recognize the switches being pulled to 0V for an active note signal. I didn't want to have to use external pull down resistors for the 25 inputs, so I utilized the 2560's internal pull-up resistors. Royce used pull-down resistors for every note in his build. I also made the following changes/updates to code: With the more versatile MEGA 2560, I revamped all the code for a single chip. I bought a ELEGOO MEGA 2560 for only $15.99. Although there is fun to be had in doing all of this, it makes more sense if you just go with an Arduino with more inputs. It also involved making up the entire circuit on a perfboard to facilitate the chips, as well as all other necessary components. Royce's setup involves using 2 separate ATmega328 chips working in tandem (2 were required because a single 328 chip does not contain enough inputs).
