Tom, I've used the second method to measure tilt with a capacitive tilt meter and it worked nicely. Can't say how it would do with the humidity sensor, but the technique works fine. I take 128 samples and throw away the lowest few bits. Andy TOM THERON on 04/13/2000 09:50:14 AM Please respond to pic microcontroller discussion list To: PICLIST@MITVMA.MIT.EDU cc: (bcc: Andrew Kunz/TDI_NOTES) Subject: [OT] Humidity Sensor Interfacing Hi all, I want to do a humidity sensing application, using either a G-Cap (General Eastern Instruments) or Smartec capacitive humidity sensor. There are diiferent ways to interface these to a micro processor, of which two are options for me to interface it to a 12c... Pic. One method is to use the sensor as the capacitive element in a RC network for a 555 oscillator, then read the resultant frequency and translate it to humidity. Other is to use an AC bridge (excitation supplied by Pic), with some amplification and then into ADC onboard Pic. The 555 option seems to me most cost effective, and easiest, but I'd like to hear if anybody else did the same type of experiment and what there findings were? Regards Tom Theron