Duet USB CNC Pendant

(work in progress / use at own risk)

This project is inspired and partly based on:

• Duet CNC-Pendant-Firmware
• Adafruit TinyUSB HID Example

It uses the GPIO ports of a Raspberry Pi Pico to create an USB Host Port (using Pico-PIO-USB) to listen for input from USB devices and generates G-Code commands to control a Duet based CNC machine.

First, the idea was to just use a simple wireless numpad for jogging.
But I later got the idea that a feature rich CNC pendant (like the WHB04B-6) should be possible, too.
So it also can read object model status responses from the Duet to pass the current axis coordinates to the pendant for displaying.

It is also possible to connect and use multiple USB devices at the same time via a USB hub.

Implementation is limited so far, see functions below.

Supported Devices

Keyboard / Numpad

• Key mapping is made for the LogiLink ID0120 Numpad, but other numpads or keyboards can be used, too.
• Arrow keys are used for jogging X/Y axes, +/- for Z axis:
  • as single step per key press (in step mode, enabled via 0/INS key)
  • as continuous movement (via special continuous mode, enabled via ./DEL key)
• Keys in the top row (num, /, *, backspace) is used to set step size (off/0.1mm/1mm/10mm).
• Other keys try to execute a macro on the Duet.
• On any key press, the Numlock LED is toggled as feedback

WHB04B-6 Wireless CNC Pendant

• Jogging with wheel with selected axis and step size (0.001mm/.../1mm) or relative speed (2%/.../100%) in special continuous mode.
• Display shows axis coordinates, spindle speed, speed factor
• Most buttons simply try executing macros on the Duet.

Implementation is based on information from https://github.com/LinuxCNC/linuxcnc/tree/master/src/hal/user_comps/xhc-whb04b-6

PS3 DualShock 3 Controller

• Jogging with directional buttons for X/Y axes, left and right shoulder buttons for Z axis as single steps.
• Jogging with sticks as continuous movements via special continuous mode
• Trigger buttons to change step size (off/0.01mm/0.1mm/1mm/10mm) or relative speed(off/25%/50%/75%/100%).
• Current step size / speed is indicated by the controller number indicator LEDs (1=0.01mm/25%, ... , 4=10mm/100%).
• Other buttons simply try executing macros on the Duet.

Other

Implementing other USB HID devices can be done by adding a adequate Pendant class and extending main1.cpp / tuh_hid_mount_cb().

Wiring

USB Pendant Socket

RPi Pico	USB A Socket	Note
GPIO 16	D+	via 22 Ohm Resistor
GPIO 17	D-	via 22 Ohm Resistor
VSYS	VBUS
GND	GND

Serial to Duet

RPi Pico	Duet 2	Duet 3	Note
GPIO 12 (UART0 TX)	URXD0	io0.in
GPIO 13 (UART0 RX)	UTXD0	io0.out
VSYS	5V_EXT	+5V	via Diode (e.g. 1N5819)
GND	GND	GND

PanelDue Serial Passthrough (optional)

PanelDue	RPi Pico	Duet
Din	GPIO 4 (UART1 TX)
Dout	GPIO 5 (UART1 RX)
+5V		5V_EXT / +5V
GND	GND	GND

Installation

• Raspberry Pi Pico
  • Compile and flash with PlatformIO, or
  • Copy firmware.uf2 to the RPI Pico after pressing BOOTSEL button while connecting to PC
• Duet Controller
  • Enable PanelDue serial interface via M575 P1 S1 B57600 in config.g
  • optionally: create macros for button functions
    • place them in subfolders inside /sys, the subfolder name depends on the used device
    • observe the console in the DuetWebControl for how to name the subfolder and file or look at the source code for each device type (src/Pendant_XXX.h)
  • optionally: add g-code/macro files for continuous mode (see ContinuousMode/Preparation)

Development Info

• Multicore usage
  • Core 0 is used for Serial connection stuff (main.cpp):
    forwarding commands to Duet, handle PanelDue/Duet passthrough, parsing object model status messages
  • Core 1 is used to USB stuff (main1.cpp):
    connection events, handle HID reports, generate commands from inputs of connected devices
  • rp2040.fifo is used to pass:
    • generated commands from Core1 to Core 0 (as DuetStatus struct object)
    • status messages from Core0 to Core 1 (as String object)
• Classes:
  • USBHIDPendant:
    • base class device implementation:
    • has helper functions for key press/release handling
    • used by:
      • Pendant_Numpad: implementation for LogiLink Numpad
      • Pendant_WHB04B6: implementation for WHB04B6 Wireless CNC Pendant
  • JSONReader: helper for identifying/buffering object model status messages from Duet
• USB device mount handling (main1.cpp):
  • on mount event and if device is supported, an object for the matching class is created and stored in devices (array of struct USBHIDPendantDevice)
  • on unmount, if device is in devices, class object is destroyed
• Known Issues:
  • Adafruit TinyUSB Library >=2.0.0 is not working with PlatformIO (?)
  • no unmount events issued with PlatformIO
    implemented workaround: periodic check if still mounted
• Not implemented yet:
  • special emergency stop handling