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.
📺 OLED
Disable for RJ12 test
GPIO 25GPIO 27
🎮 RJ12 Pendant / Expander
Enable UART2

Change a copy of the test YAML

  1. Back up the working YAML.
  2. Comment out the complete i2c0: and oled: sections.
  3. Uncomment the supplied uart2: and uart_channel2: sections shown below.
  4. 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

  1. With all power off, connect only the documented PiBot-compatible pendant or expander.
  2. Apply main power and review the boot log for UART/YAML errors.
  3. Operate one control or I/O at a time and confirm the corresponding FluidNC state changes.
  4. 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.
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