My VKLink node uses a PRM80 for the RF gateway, and needed a wiring harness to connect it to the Raspberry Pi.
I’m using DSP for all audio detection functions, which simplifies things significantly. As such, I’m only using four pins.
8: PTT. This will initiate TX on the radio.
6: Audio in. This is the radio’s audio input.
10: Audio out. This is the radio’s audio output using raw discriminator audio, so not subject to volume or squelch changes.
3: Ground: This is simply used as the common ground for the audio lines.
The wiring harness to interface it with a Raspberry Pi looks like this: