> Also a thought, does the F84 have the internal PORTB pull-ups? Are > they enabled, and maybe you have a weak internal pull-up competing > with a weak external pulldown... GREAT! It's the weak pull-ups - I remember being gotcha'd by that years ago... many thanks guys, problem fixed. Another score on the board for the Piclist! Stuart ----- Original Message ----- From: "Mike Hord" To: Sent: 10 December 2003 17:04 Subject: Re: [PIC] Input pin at 1.55volts.... > What's the input impedance of a PIC input? How about one on a chip > that's been comprimised or damaged? > > Also a thought, does the F84 have the internal PORTB pullups? Are > they enabled, and maybe you have a weak internal pullup competing > with a weak external pulldown... > > Mike H. > >Just come back to PICs after a very long break. Just updating an old > >project, on > >a 16F84. Very simple, just flashes LEDs etc. > > > >Now changed rb6 and rb7 to inputs to read a pair of simple switches, which > >are > >pulled low by 10K res, then switch pulls them high. > > > >I've set to inputs like this.... > > > >move to bank 1 > > movlw b'11000000' > > movwf TRISB > >return to bank0 > >etc > > > >then read them as > > btfsc portb,6 > >etc > > > >but when run PIC does not recognise state of RB6 and RB7 -a simple > >voltmeter > >check on them gives approx 1.55 volts when they are not pulled high by > >input > >switch. > > > >Can anyone suggest what is causing this? I think it is something simple and > >I'll > >kick myself when I realise.... > > > >Stuart > > > >-- > >http://www.piclist.com hint: The PICList is archived three different > >ways. See http://www.piclist.com/#archives for details. > > _________________________________________________________________ > Shop online for kids toys by age group, price range, and toy category at > MSN Shopping. No waiting for a clerk to help you! http://shopping.msn.com > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.