Sean and Paul,

   Right on. :)

Regards,
Anand

On 4/2/07, PAUL James <James.Paul@colibrys.com> wrote:
>
> All,
>
> And if this is the correct diagnosis, you should be able to use two
> voltmeters, one between the pin and ground,
> And the other between the pin and VCC and read voltages on both.
>
>
> Regards,
>
>
> Jim
>
>
>
> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
> Of Sean Breheny
> Sent: Monday, April 02, 2007 1:08 PM
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE]: Kirchhoff's Voltage Law - violation?
>
> Hi Anand,
>
> My guess would be that the output was actually acting as a very weak
> pull-up (perhaps it was set to be open-drain and we are looking at diode
> leakage) so that when the meter is put between the pin and Vcc, there is
> no current flow at all through the meter, so it reads 0 volts. When the
> meter is placed between the pin and ground, the input impedance of the
> meter draws enough current to cause a 1 V drop across whatever is
> pulling the pin high.
>
> Sean
>
>
> On 4/2/07, Anand Gadiyar <gadiyar@ieee.org> wrote:
> > Hi all,
> >
> >     I noticed something interesting while playing around with a
> > GAL16V8 device. I finally figured it out, but it's an interesting
> > puzzle and I thought it worth sharing.
> >
> >    Using a voltmeter, the Vcc pin shows 5 volts with respect to GND.
> > And a output pin at logic high shows 4 volts with respect to GND. The
> > same pin shows 0 volts with respect to the Vcc pin. The same is
> > observed when i used a CRO to look at the waveforms.
> >
> >    Also tried this on a PALCE22V10 device and it behaves similarly.
> >
> >    See if you can figure it out. I'm pretty sure you guys will throw
> > more light on the puzzle, else answers in two days.
> >
> > Warm regards,
> > Anand
> >
> > __________________________
> > Anand Gadiyar
> > Indian Institute of Science,
> > Bangalore - 560 012
> > __________________________
> > --
> > http://www.piclist.com PIC/SX FAQ & list archive View/change your
> > membership options at http://mailman.mit.edu/mailman/listinfo/piclist
> >
> --
> http://www.piclist.com PIC/SX FAQ & list archive View/change your
> membership options at http://mailman.mit.edu/mailman/listinfo/piclist
>
> --
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist