Custom OBD II Breakout

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K6XTC
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Joined: Sat Oct 26, 2019 12:09 am

Custom OBD II Breakout

Post by K6XTC » Sat Jul 25, 2020 6:31 pm

I've been playing around with CAN-bus in my truck. I started out with installing an after market head unit. Getting it to work with the factory amp and steering wheel controls was a challenge. It works but I would like to add more functionality which means figuring out the OID's which, unfortunately, are not published by the auto maker.

Just listening in on the bus provides a lot of traffic, most of which isn't related to the module you are trying to figure out. The solution is a bus bridge, that has two CAN interfaces, that can be placed between the module and the rest of the devices on the bus. This will allow me to easily distinguish between the two.

Hence my custom OBDII/CAN-bus breakout cable.

It is simply one male OBD connector, one female OBD connector, a piece of strip board, two 8 position dip switches, and double row pin headers in a custom designed and 3D printed enclosure.

The dip switches allow me to pass-thru all pins except for the ones I want to monitor.
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Here it is mounted with the bridge. A Raspberry Pi 4 with a seeed studio 2-Channel CAN-Bus(FD) hat.

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And here it is wired and ready to go. The CAN-bus hat accepts 12-24vdc power and supplies power to the Raspberry Pi so it is all powered off the OBD2 port.

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