CAN Shield Questions

Development Boards Arduino
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There are a few PIDs I’d like to monitor on my new Kia EV. I’m pretty sure I know what the PIDs are so I’d just like to do a simple arduino based display that shows a few of them. Questions:

  • There is an issue with EVs and cheapo ELM327 based devices not powering off with the car and thus draining the battery. I do not want to have to unplug the cable every time I park the car for an extended period. It looks like the shield sends 12V from the CAN connector straight to the arduino. I don’t see a place to disconnect 12V so I guess I’ll need to either cut traces or wire a switch into the cable. How have shield users worked around this?

  • I have a bunch of 5V Arduino minis lying around. Looks like the 2551 is a 5V chip so should be good with logic levels. (But I probably should just spring for a Redboard or a V4 Uno)

  • EVs return large payloads. As far as I can tell, the PIDs I’m looking at are probably CAN FD (64 bytes). Does the shield suppoet CAN FD and CAN XL if I need it?

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  1. Yep, if you olan on leaving it connected fulltime…Cutting or diverting a trace to a switch is probably th easiest method in my opinion

  2. Either should be fine, but it it way more convenient/resilient to use something with the larger footprint (wiring to a mini usually means the wires can wiggle/wear and tear), so I also vote for an SFE Redboard :slight_smile:

  3. No, our shield only supports up to CAN v2.0b in this design (MCP2515)

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I haven’t found the definition of CAN 2.0b vs CAN 2.0 but the 2515 datasheet does imply it will only handle frames with 8 bytes of data.

Thanks for the info.

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