What is it?

Powered by either USB or 12V (hard switchable), this is a CAN node adapter to mate your favorite Xiao device onto. Has two onboard N-Channel FETs hanging off the 12V line. Designed to handle a total of 12V 5A giving you some fun options.

MCUs tested against:

• Lilygo QT Pro
• Seeed Xiao ESP32C3
• Seeed Xiao ESP32S3

Does not ship with MCU!

Why did you make it?

I needed a tidy way to control IoT and 12V devices, namely lighting and fans off a big battery. It turns out that wireless communication is less romantic when you have to run a power cable anyway, so why not get some rock solid reliable CAN comms while we're at it?

What makes it special?

Usually to do this a lot of bare wiring and fiddly pieces are required. That bugged me, so I made this to clean up that mess and consequently fit your CAN nodes into a smaller area.

Hardware Description

The equipment is pretty straightforward:

• Mini360 buck converter backpack to get 12V down to 3.3V, enabled by a physical switch
• Tried and true SN65HVD230 for your CAN needs. RX & TX are on D2 & D3
• 120Ω terminator configurable via solder jumper
• Onboard GX12 male connector carrying CAN + 12V
• LED on D0 position
• 2x AO3400 N-Channel MOSFETs

Be sure to switch 12V off when USB is plugged in! CAN transceiver is active regardless of power source, and 12V will still go to the FETs.

Power arrives over GX12's pins. A separate power distribution board is available, or you can wire up the GX12 yourself.

Mosfets

Addressed as TRIG1 (D7 or D8, jumper selectable) and TRIG2 (D6)

In actuality there are 3x AO3400. I doubled up TRIG1 for extra power handling. Casual testing indicates it's plenty happy supplying 30W.

Be advised TRIG1 has a pulldown resistor on the gate, but TRIG2 is floating.

Kit

NOTE at this time part is only available fully assembled

Base option is the kit. Partially assembled. Includes components needed for you to populate it yourself. Be advised there are some SMDs. Kit contents:

1. Board itself
2. Everything seen in picture #3:
   1. 2x7 pin headers
   2. 1xGX12 male connector
   3. SN65HVD230 CAN IC
   4. Power switch
   5. Mini360
   6. 2x5mm FET headers
3. Additional SMCs:
   1. 2x1N5819 diodes
   2. 1x0805 100nf cap
   3. 1x0805 10k resistor

Mini360 considerations

Kit leaves my apartment with Mini360 set to 3.6V. Stay within 5% of that and double check before soldering! After diode drop that lands at about 3.3V.

I'll be experimenting with hot gluing the pot into place at some point, but for now it's adjustable.

Documentation

Pinout descriptions for GX12 is supplied as a PDF with purchase

Goes Well With

Coming soon is a ultra simple power distribution board to go with this guy. 4x GX12 + 12V terminal input. I have 'em now, just putting them through testing before listing them.

Extra Thoughts

What will you build? A motorized nerf gun cat tracking network? Your own smart LED lighting strips? Cabinet lighting which alerts you when batteries are low or someone steals your socks? So many possibilities!

Feedback on v2 is welcome. There are two reserved pins left on the 6 pin GX12. Do not use them, they are planned to carry extra power in future designs!

I use J1939 for all my own CAN stuff. If you're interested in that, test code is available here

ESP32 CAN (esp-idf twai) bringup is pretty intuitive. See official documentation

No official firmware comes with this device. Bring up is easy with Arduino