I wanted to keep my project as small as possible, and I read it can be used w/o external crystal. Since it will be on 5v source, the guides I found for reprogramming to make it run on 3.3v with internal oscilator seems wrong or can I ignore the voltage issue? Or would arduino run fine as is on 5v without external crystal?
I just need to know what is involved to make 328 usable w/o external oscillator on existing 5v source. I have access to ISP programmer shield and I have few spare ATMega 328 to play with.