At 11:14 AM 7/4/2004 -0400, Anthony Toft wrote: >In my quest of integrating my mp3 player into the car, I have come to >the front panel and I'd like to utilize the steering wheel buttons in my >'95 Grandprix, I have yet tried to figure out the protocol used (it's >one wire) but similar devices seem to have resistors that are switched >to ground by each of the buttons. If this is the case, I think I will >want to use a voltage divider between the 5v and 0v rail, with the 0v >connected to vehicle ground. Might I need to use an op-amp to sort out >the input impedance (which I don't truly understand yet). Or as long as >the resistances are at least 5k each. A common scheme. I've done it with four buttons, using an ADC input. >For the microcontroller (16F876A) board I am using the 12v from the PC >through a 78L05 regulator, will hooking these grounds together do >anything unpleasant? If everything is designed right, no. You mean the vehicle ground to the uP ground, right? The PC's 12V power supply may already be doing this, and adding a second connection gives the potential for noise pickup. Check wether ground on the PC is already connected to frame ground. If so, then don't add another ground connection. >-- >Anthony Toft > >-- >http://www.piclist.com hint: To leave the PICList >mailto:piclist-unsubscribe-request@mitvma.mit.edu -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu