@gilshultz , Bicolor would not be my goal - ideally both driving the same LED (to get the same colour). the can bus would still be interesting for negotiating, i.e. if I wanted to make it dimmable, so that if one Arduino gets the signal to PWM it at 50%, the other does the same... but otherwise, I wonder if the CAN bus is even necessary?
re: USB bus power - I power little controllers/LED combos like this all the time from the Mac, never had any issues where too much was drawn; I'd rather eliminate external PSUs where not needed.
@cedarlakeinstruments , thanks for the LED driving example, I shall test it. Can I confirm that the diagram I roughed up below is what you mean? Can I assume that PWM would not work in your example? I guess there would be a danger that the PWM coming from different power sources would not align timing wise...
I also added one momentary push switch and one endless rotary encoder to the mix; Is this safe/workable, as long as they as pictured share common GND? I know that with push switches, I should be able to find multi-pole switches, but with Encoders (though in my mind easily technically possible) I had no luck thus far (just dual shaft, but that is not the desired outcome)... would switches and encoders work when connected as below, or is there any danger of damage to either arduino?
And would it be safer to try and build external de-bouncing rather than software de-bouncing, so that the same result is guaranteed for both arduinos (i.e. would there be a potential of slightly different timing in the arduinos to result in slightly different de-bouncing outcomes when done in software)? example of a de-bouncing circuit I found online: https://www.electroschematics.com/wp-content/uploads/2015/06/rotary-encoder-arduino-wiring.png?resize=305%2C183?w=305
I assume it would be unadvisable and/or unhelpful to connect the VCCs (5V) of both; as at the very least, both arduinos would be powered by one usb connection when only one is active?
