DRA-Pi-Zero TRRS (Tip-Ring-Ring-Sleeve) Pinout:

NOTE - The 1200 / 9600 (RX) jumper must be in the "1200" position
for TRRS receive audio (tip) to be connected to the soundcard chip.

NOTE: The TRRS connector uses the following standard connection order:

Tip - Ring1 - Ring2 - Sleeve and is compatible with DigiRig Radio Cables.

Tip = Receive Audio
Ring1 = Transmit Audio
Ring2 = PTT
Sleeve = Ground