What components do I need to read road speed pulse frequency from my 2012 Jeep Compass to determine acceleration rate? I'll be feeding pulses to a Nano or Pro Mini. No drawings or sketch so far, just an idea.
My vehicle electronics knowledge is minimal.
The first thing that needs to be done is to ensure that the pulse amplitude is compatable with the input on the controller. A simple voltage divider may suffice. Also the voltage must not go below 0V. Then the pulses might need to be conditioned so that the edges are as steep as necessary. A Shmidt (sp?) trigger can help there (74HC14).
Or with automotive electronics an opto-isolator can be wise.
My problem is not so much dealing with data after getting it out of the car, its getting it out to start with, I'm totally lost when it comes to OBD, CAN, etc.
I need to know what I need to connect to the OBD connector and then to the MCU and what kind of software is needed to extract data.
Well then don't deal with CAN and OBD. Just tap into the wires coming off the sensor. You should be able to get this at any wheel with an ABS sensor or you would probably see it going into the instrument cluster. That's what all the other replies above were expecting you to do.
In my own experience the vehicle speed sensor was located on the transmission. The output signal was not digital. - Scotty
Well, I've found this:
But isn't there something a little less "precious"?
Going to try one of these just for fun:
Thanks all for input.