4.4 Connect Pendant
RJ12 UART2 connection for a documented PiBot-compatible pendant
Power off before connecting RJ12. A telephone handset or network cable may fit physically while using a different pin order. Use only the cable specified for the pendant and V4.7B.
🎮
PiBot Pendant
documented RJ12 cable
⇄
V4.7B UART2
GPIO 25 / GPIO 27
Shared-resource rule
The pendant UART uses TX GPIO 25 and RX GPIO 27. The OLED uses the same two GPIOs as I2C SCL/SDA, so the machine configuration must choose pendant or OLED, not both.
Installation
- Complete the optional RJ12 bench test first.
- With power off, confirm the pendant model, cable orientation, supply requirement and V4.7B RJ12 pinout.
- Disable
i2c0/oled and enable UART2 GPIO 25/27 at the baud rate required by the pendant; the supplied example uses 1,000,000 baud. - Connect the pendant, start the controller and inspect the boot log.
- Test feed hold, cycle start, reset and jog controls with spindle/laser disabled before real motion.
The RJ12 connector includes Vmot-main and +5 V as well as UART signals. A wiring mistake can damage the pendant or controller, so verify the accessory documentation rather than probing by cable color.
Acceptance check: the board boots every time, the pendant communicates without repeated errors, and safety controls produce the expected FluidNC state.