Changing PreScaler during interrupt

[bcd]

Its a bit messy - but it works ! Tomorrow we optimise !
This is a snippet that shows how to change the Prescaler value from within the interrupt routinue using Instant Interrupts.

DEFINE OSC 20

rs_led      var portb.7
led          var portc.4 

loops       var byte    ' count round the loop to load prescaler


INCLUDE "DT_INTS-14.bas"     ' Base Interrupt System
INCLUDE "ReEnterPBP.bas"     ' Include if using PBP interrupts


ASM
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler   TMR0_INT,  _doBAM,   PBP,  yes
    endm
    INT_CREATE     ; Creates the interrupt processor
ENDASM

OPTION_REG = %11010000 'Set TMR0 Prescaler to 2, leave RBPU alone

TMR0 =  158 ' preload with 158 to give 21uS interrupts
loops = 0

' interrupt routinue
doBAM:
toggle rs_led
if loops > 6 then 
loops = 0
else
loops = loops+1
endif
option_reg.0 = loops.0
option_reg.1 = loops.1
option_reg.2 = loops.2
TMR0 =  158
@ INT_RETURN

bill.