PicoCNC – A 4-axis CNC controller based on Raspberry Pi Pico


PicoCNC is a 4-axis CNC motion controller that works with Raspberry Pi Pico or Pico W running the open-source grblHAL firmware and can be used to control CNC routers, lathes, laser engravers, and other machines.

PicoCNC specifications:

  • Works with Raspberry Pi Pico and Pico W, or other compatible boards.
  • Storage
    • MicroSD card slot
    • Footprint for EEPROM or FRAM
  • Host interface – USB or WiFi via Raspberry Pi Pico (W)
  • CNC control via screw terminals
    • 4-axis spindle control outputs
      • 5V PWM and direction
      • 0-10V spindle control output.
      • 12V PWM support via open collector output
    • Isolated 12V limit switch input on all 4 axes.
    • Isolated standard Grbl spindle control outputs (5V): Cycle Start, Feed Hold, EStop and Safety Door.
    • 9x Opto-isolated inputs including standard Grbl controls and limits switches for all axes.
    • Relay
      • 7x relay outputs – Spindle, Mist Coolant, Flood Coolant, Dust Extraction, and 3x auxiliary relays.
      • Relay Coil voltage selectable between +5V or +12V.
      • Drive up to 11 SSR or Logic Level relays.
    • Dust collection
      • Dust Collection relay and TTL output ganged to Spindle
      • Header for a switch to manually run Dust Collector
  • Expansion
    • I2C header with daughter card mounting holes.
    • SPI header with daughter card mounting holes.
    • UART header with daughter card mounting holes (5V or 3.3V)
  • Misc – LED indicators for 12V inputs, 5V, and spindle active
  • Power Supply
    • 12V DC input via 2-pin terminal block
    • 5V regulator.
    • Flexible 12V power for isolated inputs (powered separately for isolation or off main board 12V).
  • Dimensions – 94.5 x 92 mm


CNC controller board Raspberry Pi Pico

Phil Barrett (Brookwood Design) has published the PDF schematics and a detailed user manual on GitHub. As mentioned above, the breakout board works with a Raspberry Pi Pico (W) loaded with the open-source grblHAL firmware which you could build from source following the instructions on GitHub, but most people will likely prefer to use the grblHAL Web Builder site to easily generate the firmware for the PicoCNC board.

grblHAL Web Builder

The PicoCNC motion controller board is now for sale on Tindie for $42.99 with connectors that need to be soldered, or for $28.99 for “No assembly kit, source the connectors yourself” for PCB populated with all the surface mount parts.

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