on 18/3/02 8:37 AM, Jim Martin at jimdmartin@WORLDNET.ATT.NET wrote:

Jim,

I am also a newbie, but a trick I discovered when changing from one chip to
another is to take a look in the include files.

For example, if you are working on a PIC16F84, then simply look in the MPLAB
directory for the file P16F84.inc and have a read of that file. You should
find a section called "Configuration Bits" and it should look something like
this;

;==========================================================================
;
;       Configuration Bits
;
;==========================================================================

_CP_ON                       EQU     H'000F'
_CP_OFF                      EQU     H'3FFF'
_PWRTE_ON                    EQU     H'3FF7'
_PWRTE_OFF                   EQU     H'3FFF'
_WDT_ON                      EQU     H'3FFF'
_WDT_OFF                     EQU     H'3FFB'
_LP_OSC                      EQU     H'3FFC'
_XT_OSC                      EQU     H'3FFD'
_HS_OSC                      EQU     H'3FFE'
_RC_OSC                      EQU     H'3FFF'


Here you can easily see the various options for the CONFIG word. _CP is
"Code Protect" - choose either ON or OFF, _PWRTE is "Power Up Timer" - again
choose ON or OFF and choose ON or OFF for _WDT which is the "Watch Dog
Timer". Finally, you need to choose one of the last 4 according to what
Oscilator you are using. From memory they are _LP = "Low Power" (32KHz), _XT
= "Crystal" (up to 4MHz), _HS = "High Speed" (above 4MHz to chip's Maximum)
and finally _RC = "RC Network"

I found this discovery an important step, as they do change slightly from
Chip to Chip.

The statement in your code simply takes the form of;

     __CONFIG   _CP_ON & _PWRTE_OFF & _WDT_ON & _XT_OSC

This is directly from one of my programs where I wanted;

Code Protect = ON
Power Up Timer = OFF
Watch Dog Timer = ON
Oscilator = Regular 4MHz Crystal

I think you can work out how to change the statement for your own purposes
and when you move to another chip, check out the INC file and the data
sheet.

Hope this is has been of some help.

Cheers,

Sean

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