LEGO offers schematics for the EV3 brick in their hardware developer kit accessible from the bottom of the EV3 downloads page. (Files 1 and 2 in the zip)

Do these schematics contain enough information to theoretically build an EV3 from scratch?


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Based on 3 years of extensive study of the internal workings of the EV3 as part of the ev3dev project, I can confidently say that if you build that schematic, you will get something that very closely resembles a mass-produced EV3.

There are some minor differences though. The HW Version Identification shown on page 3 of the schematic (0101 [binary] == 5 [decimal]) does not match the actual mass-produced hardware (1000 [binary] == 8 [decimal]), so it leads me to believe that the schematic that LEGO has shared is not the final revision, but rather a slightly older revision.

There is also a PIC microcontroller (U28) and MFi authentication chip (U29) on the actual EV3 that is not on the schematic. The firmware source code seems to indicate that this is used for the iPhone/iPad/iPod Bluetooth mode somehow. So, this feature will be missing from your clone EV3.

I have also just noticed that the "3 SEC delay" circuit on page 3 is not populated on the actual EV3. This is further evidence that the publicly available schematic is not the final revision.

One challenge you will face in building your own EV3 is that there is no PCB layout provided by LEGO, so you will have to do this yourself.

You will also have to find a replacement display. The LCD does not appear to be generally available. (I broke one and looked for a replacement several years ago. I ended up replacing it with a color TFT instead.)

Also, while we are on the subject, there is a BeagleBone cape called the FatcatLab EVB. There is an open source schematic for this as well. If you are really going to build your own EV3-like circuit board, it may be more appealing to copy this one because it has a faster processor and more memory.

  • Wow! So is the Ev3 technically open source hardware (just the electronics) and software?
    – Kurtoid
    Nov 18, 2016 at 3:59
  • The software is explicitly open source (mostly GPLv2 licensed). However, I have not seen any explicit mention of any copyright or restrictions related to copying the hardware schematics. It would be prudent to contact LEGO about this before selling any product that copied portions the schematics. But yes, in a broad sense of the definition, you can say that it is technically open source hardware. Nov 18, 2016 at 5:47
  • Oh man, I really want that FatCatLab EVB! Too bad there does not seem to be a way to get hold of the developers.
    – callisto
    Mar 16, 2017 at 8:43

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