From: "Jinx" > > something I've missed, does anyone have any ideas? > > You mentioned no Vref but are the comparators turned off ? Thanks for the help, but yes they were off. Unlike the F628, the F88 comparators start off disabled. The problem turned out to be related to the internal oscillator block. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist