Fan regulator - Any advise

[Jerson]

Hi Alain - I really needed coffee. Too much stress I guess. I mistook it for a 16F device!!! haha

OTOH 64 bytes RAM should be good enough to do asm interrupts no?

This is what I did with the 16F628 interrupts.

' define the interrupt handler
define      INTHAND       _IntHandler
' These variables are used to save the machine state on interrupt
wsave       var byte    $20     SYSTEM          ' location for W if in bank0
wsave1      var byte    $A0     SYSTEM          ' location for W if in bank1
wsave2      var byte    $120    SYSTEM          ' location for W if in bank2
ssave       var byte    BANK0   SYSTEM          ' location for STATUS register
psave       var byte    BANK0   SYSTEM          ' location for PCLATH register
fsave       var byte    BANK0   SYSTEM          ' location for FSR register

IntHandler:
asm
      movwf   wsave           ; Save the W register
      swapf   STATUS, W
      clrf    STATUS          ; Point to bank 0
      movwf   ssave           ; Save the STATUS register
      movf    PCLATH, W       ; Save PCLATH
      movwf   psave
      movlw   ((INTHAND) >> 8)        ; Set PCLATH for jump
      movwf   PCLATH

      btfss INTCON, INTF    ; branch if PULSEIN arrived
      goto  EndInt

; your code goes here

      ; restore the machine context
EndInt
      movf  fsave,w         ;restore the FSR
      movwf FSR
      movf  psave,w         ;restore PCH
      movwf PCLATH
      swapf ssave, W        ;restore STATUS
      movwf STATUS
      swapf wsave, F
      swapf wsave, W        ;restore W
      retfie
endasm

I have not checked the datasheet for the banks used in the 12F629, but the wsave registers may need to change accordingly. Otherwise, the context save and restore takes just 4 bytes of RAM !!!!

That also answers Damien as to the code needed for the CONTEXT RESTORE of proton