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#206527 to forums...hope I don't blunder too much.
I need to know how to interface a midi guitar to the SparkFun MP3 Player Shield.
I know that the midi guitar uses 5 volt logic.
Does the shield expect 3.3 or 5 volts on the input?
Do I need a level shifter if it's 3.3?
Also I think I'm supposed to use an opto coupler.
Will any opto coupler that works with 5V also work for 3.3V if needed?
Any other advice would be appreciated.
FYI I don't have the shield yet...I'm thinking of ordering it if I'm comfortable it will work.
Thanks, Bob
Hi Bob,

Sorry for the delay in our response here. The MIDI-IN pin is connected directly to the VS1053B on the MP3 Player Shield and is only 3.3V tolerant per the datasheet so you'll most likely need to shift that signal. VLSI's product page for the VS1053B will have the most information for that IC.

If you are looking for an Opto-isolator, we have this breakout and a bare PTH Optoisolator. If you are trying to do high speeds, the breakout is not recommended since the level-shifting circuit is transistor-based and can lock up at high speeds.

I hope this helps you get started with this project.