4 pin 3.5mm (2.5mm) plug connector at the headset cable
This page documents the 4-conductor headset and handsfree connector pinout for the PalmOne Treo 650, 700, 755p, and Centro smartphones. The layout carries left and right audio channels, a microphone input, and a common ground, and is specific to this family of devices. Only the pins listed below are covered.
| Pin | Name | Description |
|---|---|---|
| 1 | Left | audio channel (tip) |
| 2 | Right | audio channel (1st ring) |
| 3 | Microphone | input channel (2nd ring) |
| 4 | Ground | Common ground |
Notes
- If 3-pin 2.5 mm standard headphone headset detected, the pinout is following: pin 1 (tip) - mic, pin 2 - earbud, pin 3 - ground.