MIDI In works on Uno, but not Nano?

I'm having a heck of a time getting MIDI input working on a china-clone Nano. I'm using the adafruit MIDI library to receive messages through a 6N138 optocoupler as per this schematic.

It works just fine on an Uno, but my attempts using the Nano I intend to build into my final project have yielded no success.

Uploading a program works just fine so I'm ruling out a fried UART, any other ideas?

Hope someone here can help.

The Uno and the Nano use the same processor, so unless you are running the Nano off 3V3 then the results will be identical.

So you are doing something differently on the two setups.

Normally this sort of thing is caused by miss-wiring, this can be the result of a bad or faulty connection on solderless bread board if you use such a thing.

I have a feeling it is a clock problem. As stated they are the same processor but the clocks are independent. I am assuming your schematic is complete, if so it needs to be software if properly wired.
Good Luck & Have Fun!
Gil

but the clocks are independent.

No. What clocks?

Grumpy_Mike:
No. What clocks?
Da! The resonator that makes the chip work, without the clock they do nothing. In this case maybe 16Mhz? They have tolerances and errors. If what was stated is correct and all is wired correctly and the parts are good that is about all that is left. And yes I have had it happen to me.

The resonator that makes the chip work, without the clock they do nothing. In this case maybe 16Mhz? They have tolerances and errors. If what was stated is correct and all is wired correctly and the parts are good that is about all that is left. And yes I have had it happen to me.

OK but that doesn’t equate with “As stated they are the same processor but the clocks are independent.” maybe you should have said:-

As stated they are the same processor but the clocks could be different on the two boards.