I am trying to add MIDI OUT capabilities to an audio device - using the same jack. User will select in software if audio or midi is to be outputted.
I've thought about switching pin 1 of jack to GND and using pin 4 as active HIGH (to avoid possible sleeve-ring short) - but am unsure if this is best practice as midi specs are active LOW. R2 would need to be low enough to allow 5mA current loop (i.e I can't reuse R1).
Priorities for design:
- Use as few GPIOs as possible
- Low cost/part list