: > just switch the vref between Vcc and Vref in > Only need 1 chip then Yes, that would work, although you'd lose resolution with a wider Vref. Andre hasn't specified what resolution is acceptable, maybe 512 on one half is OK -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist