@Michal-Dobrzynski Please do not forget to remove the pin3-pin4 short circuit if you want to plug the Oled Expansion to any genuine Onion Omega Expansion Board Header directly because Omega2(+) may be damaged if you set GPIO11 to Low.
There are I2C level shifters on the OLED Expansion.
Pin4 of the Expansion Header provides the voltage to the lower voltage section for those level shifters.
But pin4 of the Expansion Header is connected to GPIO11 on the Omega2(+) board.
So @Onion must set GPIO11 to High (~3.3V). It's a hidden simple hack that @Onion forgot to mention for example here.
You could find some further technical details here.
Thank you all for the input! I assumed I would get email notifications of responses, and didn't think to check back until now. Unfortunately, I definitely fried an Omega2+ ! Ha! Oops. All part of the learning process I guess.
But I got worried about the voltage mismatch, thinking that the USB slave device might send back the full 5v. (Some things I read talked about 5V is actually more than intended, so that the voltage drop from the wire length could be absorbed.
Only if it is improperly implemented or you allow the signal lines to connect before the ground, something USB connectors are physically designed to avoid, but that could conceivably happen with other custom wiring schemes.
USB uses 5v power, but the signalling is 3.3v, or lower.
Looks like your connection to Community was lost, please wait while we try to reconnect.