config bits

[HenrikOlsson]

Hi,
The .inc file Joe is referring to is located in the PBP directory - it's not the one in the MPASM directory. If you open it up you'll see something like this: (this is for another PIC though)

        LIST
        LIST p = 18F4220, r = dec, w = -302, f = inhx32
        INCLUDE "P18F4220.INC"  ; MPASM  Header
        __CONFIG    _CONFIG1H, _XT_OSC_1H
        __CONFIG    _CONFIG2L, _BOR_ON_2L & _BORV_20_2L & _PWRT_ON_2L
        __CONFIG    _CONFIG2H, _WDT_ON_2H & _WDTPS_128_2H
        __CONFIG    _CONFIG3H, _MCLRE_ON_3H & _CCP2MX_ON_3H
        __CONFIG    _CONFIG4L, _STVR_ON_4L & _LVP_OFF_4L & _DEBUG_OFF_4L

It's these __CONFIG lines you're supposed to comment out in order to have them in your program OR you can edit them to suit your need in the .inc file directly but make sure you back up the original.

The file you're looking at (from the MPASM directory) is what defines names for the various CONFIG-settings (and everything else in the PIC) and it is what shows you WHICH cofig bits are available and in which CONFIG-word they are for that particular PIC.

As you can see, the .inc file from the MPASM directory is included in the project BY the .inc file in the PBP-directory (the line INCLUDE "P18F4220.INC" ; MPASM Header. It does this in order to allow you to, in your program, use "names" like PORTD, TRISD, TMR0 instead of the actual memory adress for the particular register.

Here's a part of the file you quoted earlier:

;----- CONFIG2H Options --------------------------------------------------
_WDTEN_OFF_2H EQU H'FE' ; WDT is controlled by SWDTEN bit of the WDTCON register
_WDTEN_ON_2H EQU H'FF' ; WDT is always enabled. SWDTEN bit has no effect.

_WDTPS_1_2H EQU H'E1' ; 1:1
_WDTPS_2_2H EQU H'E3' ; 1:2
_WDTPS_4_2H EQU H'E5' ; 1:4
_WDTPS_8_2H EQU H'E7' ; 1:8

This shows you the names for the "config options" available in the CONFIG2H word, so if you want to enable the Watchdog timer and set its prescaler to 1:4 you do:

@ __CONFIG _CONFIG2H, __WDTEN_ON2H & _WDTPS_4_2H

Now, this IS a confusing subject and it comes up here a lot. I usually use a bootloader and seldom mess with the CONFIG fuses in the program so I'm not very confident with it either but I hope I haven't screwed up my explanation, if I have I'm sure someone will jump in and straighten it out.

/Henrik.

[brianD]

thanks
but please explaine the following.

comment out.

if i understand correctly!
the inc file within the pbp, i copy and paste it in pbp program

or do i have to change it within the inc file?

[HenrikOlsson]

Hi,
If you want to set the CONFIG fuses in YOUR program they can't be set in the .inc file TOO, which they are by default. In order to be able to set them in YOUR you need to take them out of the .inc file.

Commenting out means convert the lines to comments so that they don't get compiled/assembled. You do that with a semicolon, like this:

        LIST
        LIST p = 18F4220, r = dec, w = -302, f = inhx32
        INCLUDE "P18F4220.INC"  ; MPASM  Header
;        __CONFIG    _CONFIG1H, _XT_OSC_1H
;        __CONFIG    _CONFIG2L, _BOR_ON_2L & _BORV_20_2L & _PWRT_ON_2L
;        __CONFIG    _CONFIG2H, _WDT_ON_2H & _WDTPS_128_2H
;        __CONFIG    _CONFIG3H, _MCLRE_ON_3H & _CCP2MX_ON_3H
;        __CONFIG    _CONFIG4L, _STVR_ON_4L & _LVP_OFF_4L & _DEBUG_OFF_4L

See the semicolon at the beginning of the lines - this is effectively the same as deleting those lines from the file but "commenting them out" instead allows you to easily revert back if need be.

Here's what happens. When you compile a program the compiler automatically adds the .inc file that is located in the PBP folder. The code in this file automatically adds the .inc file located in the MPASM folder.