On 11/3/06, Jinx wrote: > > > > Problem is that the sense pin (AN2, porta.2) is registering nearly > > the full AVdd when no panel is connected and then around 2-3V > > when the panel is connected . Is this typical for a PIC uC? > > Hi Shawn, I don't think you can read anything into the pin appearing > to be at AVdd, as it's a floating input with nothing connected. If you > look at the Analogue Input Model in any PIC manual you'll see there's > nothing to commit the pin either way. Possibly this AVdd reading is > leakage current through an internal diode, induction from nearby power > tracks, or noise from the circuit. The only important thing is that the > ADC gives good results with the source connected. Presumably the > 2-3V is the mid-position output, like so many sensors See, hooked up it should be at zero, unless someone is pressing on the panel. I say it works, but it's certainly not giving good readings. :-P I'm probably going to have to use a pull down to keep it from floating at all. What's the output impedance of the screen ? Sounds like it's going > to be fairly high, so you'll probably have to buffer it with an op amp > for the PIC, unless it has one built in ? No, it's less than 10k, so I should not need a buffer. -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- Shawn Wilton (b9 Systems) http://b9Systems.com <- New web page -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist