Here's a brief writeup on a 10-key pad variation of this idea that I=20 did. With the limitation that only one button be pressed at a time, it=20 works well. Dividing the ADC range into 10 ranges works well and drift=20 isn't a problem since all the resistors are in close proximity and are=20 at the same temperature. One lesson learned...with ten 47k resistors for the ladder, it worked=20 well. With 2k resistors, the results weren't as good. You need to keep=20 the input impedance of the ADC in mind. 10 Keys on One Port Pin?=20 Jon --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .