If you check out Microchip's web site (Sorry I don't have the address to hand),
I think you will find an app note which does this.

Joe

At 23:03 02/03/97 -0600, you wrote:
>Hello,
>        As a beginner with PIC's I don't have the programming skills to
implement
>a function that I would like to use. I have worked with the BASIC STAMP 2
>and would like to make a function that is available on the BS2. It's called
>the RCTIME command and what it does is read a resistive value by charging
>up a capacitor and measuring how long it takes to discharge through an
>unknown resistor.
>        My idea is to make a pin an output for a fixed length of time,
change to
>input and loop until it went low, count the loops and return with the value.
>        Does this sound crazy ?? Would I be wasting my time trying to debug
some
>code for this function ??
>        Any ideas would be appreciated. I'm using a 16C84 with a 4 mhz osc.
>        My goal is to read a photoresistor.
>        Thanks !!
>James and Iliana Holbrook
>Austin Texas
>Electronic hobbiest
>Automotive Technician
>Software Engineer
>
P.J. McCauley                                   Tel.  353-1-6082218
Dept. Of Pure and Applied Physics,              Fax.  353-1-6711759
Trinity college,
Dublin 2,
Ireland.