Hi Daniel

As I'm sure you have realized, OPTION is an instruction
for the 12 bit PICs and loads the value in W into the
OPTION register, which you can only write to.

The 16C63 is a 14 bit PIC and if you wish to load something
into the OPTION register you have to use the instruction
MOVWF OPTION_REG.

The watchdog timer is selected when you program the
configuration word, either enabled or disabled. You can't
stop the start or stop the watchdog timer while executing
your code. The only thing you can do to prevent a
watchdog time out, is the use the CLRWDT instruction
in your code.

regards

Gavin
--------------------------
vulcan@ihug.co.nz
http://www.geocities.com/TheTropics/Cabana/2625
--------------------------


-----Original Message-----
From:   Najemy, Daniel [SMTP:DNajemy@IMPS0014.US.DG.COM]
Sent:   Thursday, May 07, 1998 9:22 AM
To:     PICLIST@MITVMA.MIT.EDU
Subject:        Watchdog Timer

I'm trying to use the watchdog timer on a PIC16C63.

How do I turn it on?

So far I'm able to write to the options register as follows:

movlw   b'00001111'   ; Program WDT to 128 * .018ms = 2.3 seconds
movwf   81h

Note: For some reason I couldn't write to OPTION, the assembler did not
recognize this word.

I have a main loop in my program where I plan on inserting a

CLRWDT

to reset the watchdog....unless I"m missing a real obvious one, I can't
figure out how to start this
thing ticking!!

Thanks in advance....