Interface midi guitar to the SparkFun MP3 Player Shield

Sensors Sound & Audio
1

Hi…new 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

2

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.](High Speed Optoisolator - 6N137 - COM-15105 - SparkFun Electronics)](https://www.sparkfun.com/products/9118)](VLSI Solution-VS1053 - Ogg Vorbis / MP3 / AAC / WMA / FLAC / MIDI Audio Decoder / Encoder Chip)](http://www.vlsi.fi/fileadmin/datasheets/vs1053.pdf)