Hi Tom,
Thanks for the reply! I have been meaning to make a drawing in CAD. At least something functional and draw out the terminal connections. I will start chewing that elephant and have something on paper in the next couple days.
In the meantime, my INO file is attached. the code is ugly as sin and its pretty monsterous, but as I said, it works. even if the scan times are super long. Ive marked up the comments with as much info as I can to help explain what is what. hopefully it helps.
TFACC_adding_tone_logic_for_scratch.ino (19.4 KB)