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I am in the porcess of building an application which reads live telemetry data from the inbuilt car computer and sends it to Google Firebase for analysis and informational lookup on your phone and through Google Home - eg you get reminders to get you to fill up soon when your fuel tank goes below a certain level.

I've got lots of CAN BUS codes (rather than OBD) where I have the Accelerator position, Steering position, Speed, RPM, Lights on or off, Brake on or off, Clutch status etc. I could even find if anyone is sat in the seats and whether the seat belts are done up. I even have access to the dashboard dimmer switch so I could dim the screen on the raspberry pi when I move the wheel. Pretty cool.

I've kind of got the Odometer Miles, however it's about 1200 miles over range - I just wonder in the life of the car, whether that includes a degree of reverse mileage? It's not a consistent figure so Im having trouble figuring that one out.

I think I have the service miles interval, so I know when a service is due - again this is about 60 miles out.

What I would really like to build in, is real time MPG, average MPG, find out how the cars dashboard shows one odometer reading but gives me another in CAN Bus, find the service interval - when it's due.

Has anyone got any experience of deciphering CAN-BUS, especially Renault CAN-BUS codes that could point me in the right direction?

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    Interesting project @Simon! As an information security professional I'd advise you to restrict access to that portal to need to know, also be careful to keep it one way, you don't want someone hacking your car through a website! CANBUS security is woeful, just keep that in mind. – GdD May 10 '18 at 12:38
  • There have been similar questions on here in the past - have a look as they may have pointers to help you... – Solar Mike May 10 '18 at 12:51
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    The difference in odometer may just be different units or precision. Building MPG readouts is easy if you have speed and the fuel consumption (in one form or another: pulsewidth or ccs or lph). There are many general guides out there as the OBD-II spec provides most of the engine related codes. – Nick May 10 '18 at 13:08
  • I was hoping not to go down the OBD route and talk instead directly to the car computers. Very definitely going to be one way comms, and I've been reading up on calculating MPG from MAF and VSS. Need to find that outside the realms of OBD however. – Simon May 10 '18 at 13:35

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