Introducing GRBLDuino Mega Integrated

The latest project is integrating a GRBLDuino Mega Shield with an Arduino Mega – no more shield! The entire system is now contained in one easy to use board: the GRBLDuino Mega Integrated.

It has all of the same features as the GRBLDuino Mega Shield:


  • Smaller than an Arduino Mega – 3.5″ x 2.3″ (89 x 58 cm)
  • Onboard ATMEGA2560-16AUR running at 16MHz
  • CP2102 USB to UART interface – shows up as a USB serial port and works with Arduino IDE (may require Silicon Labs VCP drivers)
  • On board reset button.
  • Designed for Pololu DRV8825 stepper motor drivers and are compatible with all pin-compatible equivalents.
  • Maximum input voltage of 45 volts DC
  • Jumper selectable high/low limit switch activation.
  • RC filters on limit switch and probe inputs.
  • All machine connections are broken out to screw terminals.
    • + and – Limit switches for each X, Y, and Z axis.
    • Resume, Hold, Abort, Emergency Stop, Door Safety support.
    • Flood and Mist coolant connections.
    • Spindle Enabled, Direction, and Speed (PWM) connections.
    • Probe connection.


The schematic is pretty straightforward – it shows all of the internal connections on the board and external connectors.

Bill of Materials

  • 1x GRBLDuino Mega Integrated PCB
  • 1x ATMega2560
  • 1x CP2102
  • 1x 16MHz crystal
  • 1x micro B USB jack
  • 18x Two position screw terminal blocks
  • 6x 1×8 female pin headers
  • 1x 1×3 male pin headers
  • 3x 1×4 male pin headers
  • 4x 2×3 male pin headers
  • 1x 6mm tactile switch
  • 1x 680 ohm resistor network
  • 5x 10k ohm resistors
  • 1x 1k ohm resistor
  • 3x 100uF, 50v Nichicon capacitors
  • 3x 22pF capacitors
  • 4x 0.15uF capacitors
  • 6x 0.1uF capacitors
  • 1x 1uF capacitor
  • 1x green LED
  • 9x short 2 pin jumper shunts
  • 1x long 2 pin jumper shunts

Gerber Files

For those wishing to make their own board, the Gerber files are provided. There are no guarantees made to accuracy or completeness of these files.


I anticipate these being available for sale through a few outlets beginning in early June. Once production is up, kits (if offered) will sell for around $36 shipped in the US and assembled boards will sell for around $61 shipped in the US. Once available, the best price will be at the Eccentric Workshop store, but they will also be on Tindie and eBay.

Future Versions

Version 2 will likely add in relay drivers on the coolant and spindle enable lines to control external devices. If there is enough demand, I would explore creating a 6 axis version also.


I found a few errors once the prototype boards were assembled. The terminals for Abort, Hold, Resume, and Door were on pins 53, 54, 55, and 56 instead of 89, 88, 87, and 86.


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