Ran into a strange problem, that might be explained away, but not sure yet
since I am still investigating it.

16F877 is the chip, using 4 bits of a port, each pair tied to a pot, and the
centertap of each pot tied togeher and then to the analog input port.

I measured the voltage on a port with the bit set, and it was about 4.95
volts. Problem is across the pot it only measures 4.75 when its attached to
the two pins (bsf on one, bcf on the other).  I have the other two bits for
the other pot set as outputs so should be hi-Z as seen by the device.

I haven't yet isolated the other pot, but wonder if there is some leakage
currents going on that cause the current output to exceed the limits of the
chip and thus limit the output voltage?  Or what can cause the voltage to
change like this.  Seems to be load dependant, but not sure yet...


_________________________________________________________________
Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp.

--
http://www.piclist.com hint: To leave the PICList
mailto:piclist-unsubscribe-request@mitvma.mit.edu