Dear Friends,

What I'm trying to do is creating 1s interrupt on the background with=20
Timer0, I have set Timer0 to B2 and I need a counter for it.
It's state machine turn on and turn off LED in one second, but the "one=20
second" comes from Timer0 interrupt,
Do you get what I mean ?
Let me make it simple:

;*********************************************************************
         ; 1 ms timer function calls
;*********************************************************************
         bcf  STATUS, RP0        ;Select Bank 0
         bcf  STATUS, RP1

         ;....... 1ms  timer counter here.....

                  clrf TMR0 ;Clear TMR0 and prescaler
                  banksel TMR0
                  movlw 0xB2 ;Count=3DB2
                  movwf TMR0

*How can I make the 1ms counter here ?*

         ;....................................
     ;....................................

         incf COUNT, f
         movlw  .10        ;Compare count to 10 decimal
         subwf COUNT, W        ;Store the result back in
         btfss STATUS, C        ;Is the result 0, skip if no
         goto exittimer

         clrf COUNT        ;Clear count register

;**********************************************************************
         ; 10ms timer function calls
;**********************************************************************
         ;....... 10ms  timer counter here.....

*How can I make the 10ms counter here ?*
         ;....................................

         incf COUNT1, f
         movlw  .10        ;Compare count to 100 decimal
         subwf COUNT1, W        ;Store the result back in
         btfss STATUS, C        ;Is the result 0, skip if no
         goto exittimer
         clrf     COUNT1
;**********************************************************************
         ; 100ms timer function calls
;**********************************************************************
         ;....... 100ms  timer counter here.....
*How can I make the 100ms counter here ?

          The interrupt will trigger state 1, which is turning on LED=20
from here, how can I do that ?*
         ;....................................

any ideas or clues will be appreciated
Thanks for replying...

On 1/07/2013 12:24 PM, Byron Jeff wrote:
> OK. I'm going to critque the code now.
>
> On Mon, Jul 01, 2013 at 07:09:02AM +0800, Electronic Consultation wrote:
>> Yes this the first time I used assembly for PIC, most of the time I used=
 C.
>> if I want 1 ms on 20 Mhz processor with 1:64 prescaler ?
> It cannot be done. A 1:64 prescale on a 5 Mhz instruction clock will give
> you a 12.8 uS tick rate. There is no integer number of counts of 12.8 uS
> that will give you 1 mS.
>
>> Something like this ?
>> *on init :*
>> clrf    TMR0            ;Set timer 0 to 0 - may not be needed
>>
>>           clrwdt                ;Clear watchdog timer
>>
>>
>>           bsf     STATUS, RP0        ;SELECT BANK 1
>>
>>           ; Set up timer interrupt
>>           movlw     b'10010110'        ;weak portb pullups disabled  -
>> 1ms interrupt
>>           movwf     OPTION_REG        ;select tmr0, 64d prescal, clock s=
ource
>>
>>           bcf     STATUS, RP0        ;Select bank 0
>>
>>           bcf         INTCON,RBIE        ; port B interrupt on change di=
sable
>>
>>           ;movlw      b'1010000'        ;enable global/timer0 interrupt
>>           movlw      b'10100000'        ;enable global/timer0 interrupt
>>           movwf     INTCON            ;
> Where exactly does the interrupt go?
>
>> *for 1ms:*
>>       LedTimer EQU 0x0A
> Is LedTimer an address or a count. If it's an address then I don't think
> 0x0A is a General Purpose register on the 16F648A. Also take a read of my
> discussion earlier about the use of CBLOCK instead of equates.
>
>>            clrf TMR0 ;Clear TMR0 and prescaler
>>                    banksel TMR0
>>                    movlw 0xB2 ;Count=3DB2
>>                    movwf TMR0
>>
>>               timer1ms
>>                 movf LedTimer,f
>>                 btfsc STATUS,Z
>>                 decf LedTimer,Z
>>            return
> Tthe timer1ms code makes little sense. First off it doesn't use Timer 0 i=
n
> any way. If it's an interrupt service routine, it needs a retfie. If not,
> then is doesn't have a loop. If only decrements the LedTimer, which again
> is not a proper address, when it is already zero. You never assigned a
> value to LedTimer, so it's unclear if the decrement will ever execute.
>
> I really think you need to take a step back, stop trying to write code, a=
nd
> just explain what it is that you are trying to do. Right now the code is =
so
> confusing, that no one can really help you.
>
> As I always tell my students, programming isn't about writing code, it is
> about solving problems. Please explain the problem that you are trying to
> solve.
>
> Hope this helps,
>
> BAJ
>
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