Timer and long (hours) sleep period - how to?

[flotulopex]

I really need some help on this one. Does anybody have a code sample using Watchdog timer?

I read the "Watchdog Timer Operation" datasheet, but it is still not very clear to me.

Here is my piece of code (that works) when I don't use the WDTCON postscaler:

' Fuses
@ DEVICE PIC16F88,INTRC_OSC_NOCLKOUT,PROTECT_OFF,WDT_ON,PWRT_ON,MCLR_ON
@ DEVICE PIC16F88,BOD_ON,LVP_OFF,CPD_OFF,DEBUG_OFF,CCPMX_OFF

'-------------------------------------------------------------------------------
' Register settings
OSCCON       = %01100000    'Internal RC set to 4MHZ
ANSEL        = %00000000    'Disable Analogue Inputs
OPTION_REG   = %00000111    'enable PORTB pullups, prescaler to WDT, rate 1:128
'WDTCON       = %00000001    'Prescaler 1:32, WDT ON

'-------------------------------------------------------------------------------
' Init
LED1 var PORTB.0

'-------------------------------------------------------------------------------
' Program
MAIN:
    toggle LED1
    NAP 7
    goto main

end

If I use SLEEP instead of NAP, I can set up the sleeping time up to more than 18 hours.

It looks as the pre- or postscaler don't affect the sleep period... (?)

I'm completely lost....