Hello Julian,
Actually you just need either :
- to play with any Midi compatible controller, to send Midi CC which shall change the parameters of the chip according to the Midi mapping table.
- to edit the corresponding lines in setup() function. However, normally it should stay lound while key is pressed, sustain is maxed up by default.
Maybe something goes wrong with the Midi implementation, I hate Arduino Midi library btw.
There is better than the VST now : a SIDaster user made a great GUI with Processing, I will ask him if I can share it on the website.
On my side, lots of work going on with the SIDaster. Since Arduino Midi library is buggy (missing alot of Midi in messages), I'm currently re-programming the SIDaster using a home made interrupt driven Midi engine with a large buffer and optimised Midi message handling, to lower processing time (e.g., I discard everything that is not CC, or Note, Or pitch bend). Moreover, I have implemented a nice pitch/bend feature, with 32 steps between each note stored in program memory, that brings a lot of playability to the SIDaster.
Expect a V2.0 soon.
Bonus, here is a pic a SIDaster user sent me, he added an I2C screen and rotary buttons to his synth. Lovely !