Ok, I am a bit late cuz I wanted to give it some try first, and I did.
The project I was referring to is: https:
I managed to make my mega act as USB MIDI instrument by burning special firmware in, but the above sketch is not working.
Then, I tried an example midi library that comes with arduino IDE and that works! It generates sequence of midi notes and all the PC audio software plays it.
So it's about the sketch OR me not connecting pins right. I did check keyboards flat cable connectors with a multi meter and the situation is pretty clear. There are 8 x (8x2) matrix. The 8x2 is cuz double switches for velocity. Tbh, I didn't connect whole matrix but just some keys, but that should work? I didn't change pins in the sketch just connected the key according to the original code. Nothing happens when I press that key. Shouldn't there be an event if any row/column combination is switched on?
Another thing, there is a thick black wire. That is a ground? Tried to connect it to ground pin on digital pins row but no change.