MCP2515 CAN Bus Risk Mitigation Questions

I'm working up a device that reads MPH. If some friends want to try it out, I'd like to make sure I'm not at risk of kindly messing up their car's computer.

So, what risks do I face with using a MCP2515? The ones I can think of currently are:

  • accidentally sending data that ought not to be sent
  • a short onboard Arduino/etc that causes voltage to be sent to HI/LO that shouldn't be there

It seems that the first step would be making sure the code & libraries have all "send" methods removed. All of the libraries I have tried seemed to have some quirks to them, and I'd hate for one of those quirks to be accidentally sending the hex code for the "eject driver" feature.

Perhaps the risks are low, but before telling friends "hey try this" I'd like to identify the risks.

Reading the datasheet I'll find the way to go, pag. 57 - Modes of operation . Listen only mode is what you are looking for, after setted the chip will not attempt to send any data, including the ack.

Ciao, Ale.

ilguargua:
Reading the datasheet I'll find the way to go, pag. 57 - Modes of operation . Listen only mode is what you are looking for, after setted the chip will not attempt to send any data, including the ack.

Ciao, Ale.

Excellent, thank you. I'll look more into it tonight, but from first glance, CANCTRL seems to be exactly what I'm after.

And, good news about the ack. Previously, I saw online where someone had desired listen-only mode with ack...which to me, is not listen-only mode. I like the feeling of knowing that I'm not sending anything to the CAN bus since the CAN bus seems to be some sort of deep dark magic that I do not wish to fully understand.

... however:

I'm not a lawyer or an insurance agent but if you build something that you "hook-up" to any device that has regulatory compliance requirements; you may be breaking laws and may find yourself in serious trouble should a mishap occur.

Ex 1: Friends attach your device and take the automobile for a spin on freeway in heavy traffic. The automobile stalls and the car behind crashes into them. The car is impounded while the State/Feds attempt to discover what caused the engine go turn off. The rear car driver hires an attorney to recover pain and suffering and the fact that an unauthorized device was connected to the CAN bus becomes an item of importance.

Ex 2: Friends attach your device and go for a ride. All is fun until the police pulls ghem over for distracted driving. Seeing the home-made device, the policeman believes it to be a timer to blow up the fuel tanks. Your friends are arrested as possible terriorists. Things go downhill fast....

Ray