Need Help in Measurement of Voltage

[eddyh]

HELLO TO ALL, HOW I CAN WITH THE 16F84 TO NAME THE PORT OF 0 TO 12, AND I KNOW portb.0 to portb.8 and porta.0 to porta.4 EDDY.

[NavMicroSystems]

apache,

for a start I would recommend to use a 10 turn precision trimmer (10k) as a voltage divider.
(they are about 50 cent)

You don't have to worry about the temperature range.
The overall resistance of the trimmer may change with with the temperature, but this value does not really matter, the only thing that does matter is the ratio (R1:R2)
and that does not change.

+10-18 V -----------
                    |
                    -
                  \| | 
                   |\|
                   | |\______ to PIC ADC
                    -
                    |
  Ground -----------