3.1 Test RJ12 Port

Advanced test · UART2 for a compatible PiBot pendant or I/O expander

RJ12 and OLED share GPIO 25 and GPIO 27. They cannot be enabled at the same time. Power off before connecting the accessory and never assume a generic telephone cable or third-party pinout is compatible.

Change a copy of the test YAML

Back up the working YAML.
Comment out the complete i2c0: and oled: sections.
Uncomment the supplied uart2: and uart_channel2: sections shown below.
Upload under a new filename, select it with $Config/Filename, and restart.

uart2:
  txd_pin: gpio.25
  rxd_pin: gpio.27
  baud: 1000000
  mode: 8N1

uart_channel2:
  report_interval_ms: 75
  uart_num: 2

Test

With all power off, connect only the documented PiBot-compatible pendant or expander.
Apply main power and review the boot log for UART/YAML errors.
Operate one control or I/O at a time and confirm the corresponding FluidNC state changes.
If the ESP32 does not start, power off and remove the accessory before diagnosis.

The RJ12 carries GND, Vmot-main, +5 V, GPIO 25 and GPIO 27. The exact cable and accessory wiring must follow the PiBot product documentation.

Pass: the controller starts, UART2 reports no error, and the connected compatible accessory communicates reliably while OLED is disabled.

← 2.12 Check DoneAdvanced 1 of 23.2 Test RS485 Output →