All In One Electronics

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All In One Electronics

Release status: Experimental

A Motherboard for all the electronics needs of the RepRap Mendel. Based on JohnnyR's Pololu Shield, but expanded.
CAD Models
External Link


This motherboard was based on JohnnyR's pololu shield for the arduino mega... I designed it to be flatter (less vertical) but larger in footprint. It measures 4" x 6" in total. The design only stacks 2 boards deep. The Pololu drivers are beside the main arduino. And the design plans for active cooling. All the hot components are on the side seperate from the arduino, so that ducted cooling can be used.

In addition I have expanded out the capabilities. with an onboard extruder controller, and a heated bed driver. I've also added headers for an LCD/keypad, Ethernet, and SD Card, as well as an expansion port. Trying to max out the potential of the arduino mega, so that this board can easily be expanded in the future without starting over.

Also the board is hopefully designed so it can be printed with the mendel (the etch resist mask)

This page will be updated and fleshed out as I have more time, but there were some interested parties, so I thought I would get the initial info up.

If anyone is interested in testing this out, please contact me on IRC as Glasswalker/Glasswlkr and I'll try to help. I'll figure out an option for email shortly.


This is completely un-tested as of now. I'm still in the process of building my reprap. The firmware that works on JohnnyR's pololu shield should also work on this board, (with the exception of the lcd/keypad). But it WILL require fine tuning (I'm using different digital I/O pins than he is, so you will need to customize that in the firmware before installing it).

If you want to test this out, you do so at your own risk, I can't be held responsible for any damages, death or dismemberment (I'm not quite sure how dismemberment would result from the use of this board, but hey you never know right?)

3D Render

Here is a simple 3d render... The SIP Headers don't render out quite right, and this of course doesn't show the pololu or Arduino on there. And it doesn't include the heatsinks that I plan on installing.

Also the headers for LCD/Keypad and Expansion all are meant to be right angle sip headers. for lower profile under the arduino.




  • Original board
  • based on JohnnyR's design for the Pololu Shield.



  • Added isolation caps to the VR circuit, for improved stability.
  • Moved the keypad/LCD interface for mechanical reasons (wouldn't fit under arduino where it was)
  • Rearranged a few IO pins for optimization reasons



  • Added pull-down resistors to the heater driver MOSFETs to keep their input signal stable even if the micro drops those pins to floating.
  • Removed the second extruder, and all related electronics. My thinking is that 90% of people won't need dual extruders working at the same time, and this will cut costs down on the board. We can always add an extra "multi-extruder" board as an expansion in the future.
  • Since I was able to free up some IO with removing the second extruder, I re-optimized a few traces, and added dedicated headers for an Ethernet port, and an SD card expansion. (without using up the other 14 pin expansion port on the top of the board). This gives us more expandability and allows the use of cheap sd and ethernet options.


Schematics were done in Isis, so I'll have to save them out in another more usable format later. For now this lets you all see it.





Bottom Copper layer for the board. This can be printed and etched, but I suggest using one of the proper scale files in the source files section of this page such as the pdf, dxf, or eps files. Or when I have them uploaded, the gerber. This image is flipped so that it will etch for bottom copper properly.




Source Files






Coming Soon!

PDF Files

Bottom Copper PDF: File:Mendel Motherboard PCB Copper.pdf
Silk Layer PDF: File:Mendel Motherboard PCB Silk.pdf
Schematic PDF: File:Mendel Motherboard Schematic.pdf

Firmware Source Files

Coming Soon!

Zip File Containing All Files

Coming Soon!