MoTeC Global Forum

I am trying to set up some functionality where an analog input would be used on another (Non Motec and without user CAN configurability) device in my car based on a counter in my PDM.

Is it feasible to use a table in my dash (Using the PDM counter output on CAN as an input to the dash) and a PWM output to generate a variable DC voltage for input to the other device? I would imagine I would need to build a small LCR filter circuit to smooth the output from the dash but if it is something that is just never going to work I will have to think of another way. It is actually intended to be an input to control trim on an external boost controller from buttons on a keypad attached to my PDM but I may well find other uses if it is feasible.

I think you can make that work, here's an example of the smoothing circuit you might use:

http://www.ontrak.net/pwm.htm

I guess I should just have a crack at it. It is not as though it will cost me much in componentry. The input to be driven has a decently high input impedance so load on the output of the dash or on the filter circuit itself should not pose a problem.

I suppose using an inductor is probably a bit belt and braces. reliability should not be an issue either if values around 1uf are useful. That lets me avoid electrolytic caps so no future issues with drying out electrolyte and drifting capacitance.