WORD bug

[Bruce]

Hi Yettie,

I couldn't get your code to compile without errors. Try this;

@ DEVICE MCLR_OFF,LVP_OFF,HS_OSC,WDT_OFF
DEFINE  OSC 8
define  debug_reg    	porta		'nevermind my serial LCD display debugger
define  debug_bit   	0
define  debug_baud   	2400
define  debug_mode   	1

define  inthand     	checkNow
 
CMCON=7
TRISB.3=0

'Variables for saving state in interrupt handler
wsave	           VAR	BYTE $70 system		' Saves W
ssave	           VAR	BYTE bank0 system	' Saves STATUS
psave	           VAR	BYTE bank0 system	' Saves PCLATH
fsave	           VAR	BYTE bank0 system	' Saves FSR
time	           var	word
flag               var  byte
decideTimeInterval var	word
TIMEINTERVAL       con  600

;-----------------------
setup:
  debug   12,"Starting",10,13,"   Program",4
  pause   2000
  
  intcon  = %11000000   ;setting up gie and peie bits
  time    = 3036          	;calibrated to have 31.25ms scale
  tmr1H   = time.highbyte
  tmr1L   = time.lowbyte   	;65536 - time (preload value)
  flag    = 0
  decideTimeInterval = 0
  PIR1.0  = 0
  PIE1.0  = 1

  T1CON   = %00110001    ;setting up to 1:8 prescale
                          	;31.25ms x 8 = 250ms/count
;--------------------------------
main:
  if flag = 4 then        	;(250ms x 4 = 1s) second ticker
     flag = 0
     decideTimeInterval = decideTimeInterval + 1
     gosub  updateTime
  endif

  if decideTimeInterval = TIMEINTERVAL then		;this one is the notorious routine. it's just a reset condition.
     decideTimeInterval = 0				;It resets unexpectedly.  In contrast to this,
  endif							;changing the decideTimeInterval to BYTE and of course
							;TIMEINTERVAL <= 255 will function properly
  goto main
;----------------------------
updateTime:
  DEBUG "Time:",#decideTimeInterVal
  return
;------------------------
;interrupt handler
asm
checkNow
    ; Save FSR, PCLATH, STATUS and W registers
    movwf	 wsave          ; Save W
    swapf	STATUS, W   ; Swap STATUS to W (swap avoids changing STATUS)
    clrf	STATUS	     ; Clear STATUS
    movwf	ssave	     ; Save swapped STATUS
    movf	PCLATH, W   ; Move PCLATH to W
    movwf psave	     ; Save PCLATH
	
	; isr routine
    bsf STATUS,RP0  ; bank 1
    bcf PIE1,0
    bcf STATUS,RP0  ; bank 0
    incf _flag,f    ; increment flag
    movlw 0x8
    xorwf PORTB,f   ; toggle portb.3
    movf _time,W
    movwf TMR1L
    movf _time+1,W
    movwf TMR1H 
    bcf PIR1,0
    bsf STATUS,RP0  ; bank 1
    bsf PIE1,0
    bcf STATUS,RP0  ; bank 0
    
    ; Restore FSR, PCLATH, STATUS and W registers
    movf	fsave, W      ; retrieve FSR value
    movwf	FSR	     ; Restore it to FSR
    movf	psave, W	     ; Retrieve PCLATH value
    movwf	PCLATH	     ; Restore it to PCLATH
    swapf	ssave, W	     ; Retrieve the swapped STATUS value (swap to avoid changing STATUS)
    movwf	STATUS	     ; Restore it to STATUS
    swapf	wsave, F	     ; Swap the stored W value
    swapf	wsave, W     ; Restore it to W (swap to avoid changing STATUS)
    retfie		     ; Return from the interrupt    
endasm      

    end

Look in the manual, and at some of the MeLabs examples for assembler interrupts to find out why it works.

[yettie]

Hi Bruce

the code is actually working to my circuit. it's just that there might have some differences in our compilers. i'm compiling it in PBP with IDE of microcode. just to study the (bug?), i'm changing the "time" variable to WORD or BYTE modifier. using the WORD seems to be not working properly other than the byte. i already prototyped this program and testing it further. I will share you further info of what more I can find out. thanks!

Regards,
Yettie