PiBot Wiki

The main function of this board is to expand I/O capability, solving the problem of insufficient I/O ports on the ESP32.

A comprehensive guide detailing all features is available on the FluidNC wiki, which we recommend reviewing.

Additionally, PiBot provides a quick-start tutorial to help you get up and running swiftly in PiBot wiki.

This is an add-on board for FluidNC CNC controllers. It uses only 2 I/O pins from your ESP32 to provide 18 additional configurable pins and includes an RGB LED. It also features a dedicated connector for a pendant or smart display.

The board extends I/O via a UART connection, offering inputs for switch detection and outputs configurable as digital or PWM.

For your convenience, the board is pre-loaded with firmware prior to shipment.

1. Expander V4 Main unit × 1 (SKU:PIPDT400B01)
2. RJ12 module × 1 (SKU:PIRJM012B01)
3. RJ12 communication cable (0.3m) × 1 (SKU:PIRJC012B01) – [300mm is standard (default). You can optionally select the 1000mm version.]

• (4x) opto isolated inputs
• (4x) photoelectric limit switch inputs - Like the 3D printer Switch（only in PiBot Board）- also can configure as a normal button input.
• (4x) 5V outputs (PWM capable)
• (2x) MOSFETS 40V 8A (PWM capable) outputs
• (2x) Solid-state relay output rating: 40V, 2.5A （only in PiBot Board）
• (2x) Pin output only （only in PiBot Board）
• (1x) RGB LED status indicator. This is used to show the status of the firmware during booting and can then be used as indicator by the user as output pins 18,19 and 20.
• LED indicators on every input and output.
• Terminal blocks on all I/O for easy connection
• (1x) RJ12 UART input to connect to your controller
• (1x) RJ12 UART output to connect to your pendant or smart display
• (1x) 6“ RJ12 cable to connect to controller

This module is designed for UART communication through an RJ12 connector. Controllers that feature a dedicated I/O Module socket will need a corresponding RJ12 breakout module to establish the connection.

For flexibility, we have included 5-pin headers on both the main and expansion boards for connection via Dupont wires. Please be aware that the quality of wires and connectors is critical for stable communication.

For UART-based pendants, connect them to the RJ12 port labeled “To Pendant” on the expander.

Please use the firmware version with a baud rate of 100,000, as the expander only supports this baud rate version.

Step 1: Prepare a controller board with FluidNC firmware version 3.9.7 or newer installed. Load the provided YAML configuration example onto it. Then, connect the RJ12 cable and link the board to your computer.

Step 2: Open the folder of FluidNC firmware version 3.9.7 or above, double-click on “fluidterm”, select the appropriate port to enter the program. Wait for the program to appear, then press CTRL+S, select the “firmware.bin” firmware, enter ”-W“, and press Enter.

Step 3: press the BOOT0 button and hold it while pressing and releasing the RESET button. The device will enter bootloader mode and stay in that mode until it is later reset without the BOOT0 button held down.

You need to create a UART. The ESP32 has three (0, 1 & 2). The standard USB/Serial port uses 0, so you must use 1 or 2.

The baud for the extender is 1000000

The passthrough_baud should be 57600. In this case the passthrough is referring to passing data from the primary FluidNC serial port to the UART being defined. This is used when uploading firmware from FluidTerm.

If you are using a display or pendant on the second UART, you should have a report interval other than 0.

uart1:
  txd_pin: gpio.25
  rxd_pin: gpio.27
  baud: 1000000
  mode: 8N1
  passthrough_baud: 57600
  passthrough_mode: 8E1

uart_channel1:
  report_interval_ms: 75
  uart_num: 1
 

There is an ST-Link header connector on the Stm32. It ls located below the boot and reset buttons. Use the STM32 ST-Link Utility program. Connect the ST-Link as follows

ST-Link   | Stm32 expander
3.3V      |  3v3
GND       |  Gnd
SWDIO     |  SWD
SWCLK     |  SWC

https://www.st.com/en/development-tools/stsw-link004.html

Re-Power on the main controller. It will power the Expander. You should see the a LED light near the RJ12 connector and the RGB status LED should light with all colors on.

Check your startup messages for errors.

Yaml code example

coolant:
  mist_pin: uart_channel1.14
  flood_pin: uart_channel1.15

Enter the M7 command, and solid state relay light 1 will illuminate as shown in the figure.

Enter the M8 command, and solid state relay light 2 will illuminate as shown in the figure.

Enter the M9 command, and all lights will turn off.

You can now design your machine parameters by referring to the YAML file we provided.

PIN I/O #Number configuration details from Diagram Overview or the PCB Silkscreen specifications as reference.

Assigns pins to functions in your config file.

The pins are labeled with a number. This is the number you use in the config file. You specify the UART channel number and the pin number like:

limit_neg_pin: uart_channel1.4:low

mist_pin: uart_channel1.14

Note: This number has nothing to do with the STM32 pin numbers, Like A5, B11, etc. These are numbers assigned for the Airedale in the expander's firmware.

Be sure to only assign input pins to input functions and output pins to output functions. If you make a mistake, nothing will break, you just get a warning in your start messages.