Connecting the PixyCAM to LEGO Mindstorms using I2C    Send article as PDF   
In order to use the PixyCAM with the LEGO Mindstorms EV3 or NXT kit, you will need an I2C Adapter Cable. You can order a cable through some PixyCAM distributors, including the Robotshop. The PixyCAM for LEGO Mindstorms comes with a special Pixy-to-Mindstorms Cable, and is preloaded with a version of the firmware that speaks with the LEGO protocol by default. If you have Pixy for LEGO, just to the PixyMon Settings section below.

pixycam lego mindstorms cable

Using the “Standard” PixyCAM:

If you have “Standard” PixyCAM, you can still hook it up to LEGO Mindstorms, but it will require you to make a cable. This is fairly easy, but you must have the correct hardware revision of PixyCAM. Look on at the backside of your Pixy, and compare it to the picture below which shows the Revision R1.3A’ If so, your PixyCAM will work with LEGO.


If the backside of your PixyCAM looks like the picture below showing revision R1.3, unfortunately your PixyCAM is not compatible with LEGO Mindstorms


The only difference between these two PCB Revisions is that R14 and R15 are 82K for revision 1.3A instead of 4.7K for revision 1.3. Replacing surface-mount resistors is fiddly and requires a decent amount of soldering skill which is probably best left to the professionals.

Making your own LEGO Mindstorms comaptible Cable requires a few parts. I recommended that you use a 10-pin IDC connector, like this, which is already crimped with a ribbon cable, or this. You also need a LEGO Mindstorms Connecting Cable that you don’t mind chopping up, because the offset modular connectors used by LEGO are hard to source. If you have a LEGO Mindstorms EV3 or NXT kit, you have several of these cables, but if you don’t want to sacrifice one, you can buy them from the LEGO Shop, or from BrickLink, among many other places as well.

Below is the connection diagram:


The black and white wires on the LEGO Mindstorms Cable are not connected to anything, and can just snip off. Similarly, the pins 1, 3, 4, 6, 7, and 8 on the 10-pin IDC are also not used.

Configuring the PixyMon Software:

Once you have made up the Cable, you’ll need to set the Data Out Port to LEGO I2C in the Interface Tab of the PixyMon Software. 


You are now ready to start using the PixyCAM with your LEGO Mindstorms NXT, or EV3 kits.

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