I’ve added a fuel pressure sensor to my truck which sends the data from a Thing Plus C in the engine bay to a Raspberry Pi in the cab using wifi. I’m thinking about adding some more sensors for measuring various temperatures, engine fan RPM, etc. Would it be possible to use something like the QwiicBus system for both powering sensors and reading their data using I2C? The benefit would be not needing microcontrollers scattered all around nor dealing with wireless.
Has anyone here used something like this in an automotive application? Any tips, tricks, or things to watch out for?
Thanks for any advice.
I don’t think qwiic is going to be a good fit for a automotive application because it’s limited to about a meter in length. While there are ways to extend length, they add cost and complexity to your design. Add to that automotive environments are very electrically noisy and qwiic / I2C’s intolerance to interference on the bus and I think you’re just looking for trouble.
CAN bus would be much better and is already extensively used in automotive. There are not many CAN sensors around so you’d need a way to get any sensor communicating on a CAN bus through converters.
RS422 or RS485 serial would also be better choises but again, you need some way to get your sensors talking on those as well.
Automotive applications can be tricky, whatever you do you need to build in a way to deal with noise and bus lengths.
That’s what I was suspecting. That’s why I was thinking about that QwiicBus system which is basically I2C over ethernet.
I’ve run CAT6 direct bury ethernet (seems to have some shielding inside the cable) from the cab, under the firewall following some HVAC hoses, and into the engine bay. This is on a Hummer with the GM 6.5 turbodiesel. Plenty electronically noisy for sure. Since I don’t have the QwiicBus system yet I’ll do some testing with just ethernet and see if TCP/IP can hold up to the noise. I’ll report back.