Jim,
To connect a microphone or UART through a USB Type-C connector, your implementation will need to comply with the guidelines defined for the "Accessory Modes" on the USB type-C specification. I recommend you to check appendixes A (Audio Adapter…
I got some additional feedback from a member of this team:
A switch that detects the correct GND/MIC/ etc orientation on an audio jack that has been plugged in (TS5A225E)
A switch that goes behind a micro-USB connector and can switch to an audio…
