Hi CD,
I’m excited to announce the release of two PCB designs.
CAN Terminator
This board allows for a drop in CAN termination point for the end of your loop. It comes in two variants, one with a Molex connector, and one with a Wago lever terminal.
CANvertible
The CANvertible PCB allows teams to switch on and off termination at any point in the CAN loop. With a passthrough and terminator option, this is perfect for any robot with motors that stick out of the frame perimeter.
Gone are the days of rushing to rewire your CAN loop when your intake breaks between matches. With this board, you can be up and running again at the flick of a switch! This also comes in Molex and Wago lever terminal variants.
Both boards feature a through-hole resistor for easy repairs, and zip-tie holes for mounting. In the coming weeks, I’ll be making a 3D-printed case for both of them, so stay on the lookout. Both the design files and gerbers are up on my GitHub, so feel free to modify them as you see fit.
I’m also thinking of doing a limited run (hopefully before build season) in a group buy style of these boards, but I’m not sure how to best handle shipping/distribution without it being too costly for either myself or you all. If any of y’all have experience with this, please let me know.
For stuff and giggles I uploaded the WAGO termination kicad to DigiKey and tweaked options to enable their “DigiKey Red” pricing. At qty 10 it priced the PCBs at $1.48/ea with a 10 business-day lead time. I added the WAGO connectors (p/n 2946-233-502-ND) but struggled to find a 120Ohm resistor that fit the exact spec in the kicad, but settled on this p/n 120QBK-ND which matched your length but was a touch thinner.
All told, shipped and with tax it was $38.44 for qty 10.
Something like this, especially if DigiKey offers a voucher in the Virtual KoP again this year should put these designs well with reach of nearly every team (or small group of teams).
Working on something like this, but I’ve got some exams coming up so it might take time. The easiest way I’ve thought of doing it would be to search for CAN faults and then send a digital output from the rio to the device to shut it down. Relays are a little bulky, so I was trying to use MOSFETs but I’m still working out some of the kinks
Thanks for doing this! I’ve been looking at PCBWay for my pricing but totally forgot that DigiKey gives out that voucher, I’ll definitely take a look at them too
Star network topology should help you, probably easier than dealing with automatically disconnecting a lost termination or network segment. some people talked about it here
As CAN bus speeds get higher, adherence to a bus topology is important. Star topologies tend to have long “drops” or branches from the hub, which can introduce further signal integrity issues.
Agreed. The most I would consider a star-like topology these days is sitting on a swerve module grabbing the 2 motor controllers and an encoder in their short legs.
I can’t cite a source but I recall reading that “proper” topology matters more in CAN-FD buses than CAN2.0 busses.
