PIC16F84A using pulsout and TMR0

[HenrikOlsson]

Hi,
Basicly you can have as many interrupts sources as the PIC has (TMR0, TMR1, USART, RB0, RBChange, CMP, ADC, whatever.....). When the program interrupts and starts executing the ISR (InterruptServiceRoutine) you need to check what caused the interrupt and act uppon it accordingly.

My approach to this would be to use an external 32.768kHz xtal, set the TMR of your choise up to generate an interrupt at 100Hz, then in the ISR count those ticks. When you have 100 ticks you have a second. When you have 216 ticks, toggle your step pin.

Ticks var byte             '1/100th seconds
StepTicks Var Byte      '1/100th seconds, used for step pulse timing
Seconds var Byte        'Seconds
Minutes Var Byte         'Minutes
Hours var Byte            'Hours
Days var Byte             'Days, perhaps change this to a Word.

Goto Main                  'Jump over ISR.

DISABLE

ISR:
'Reload timer with correct value here, and restart it.

Ticks = Ticks + 1
If Ticks = 100 then
  Ticks = 0
  Seconds = Seconds + 1
    If Seconds = 60 then
      Seconds = 0  
        Minutes = Minutes + 1
        If Minutes = 60 then
          Minutes = 0
          Hours = Hours + 1
            If Hours = 24 Then
              Hours = 0
              Days = Days + 1
            Endif
        Endif
     Endif
Endif

StepTicks = StepTicks + 1
If StepTicks = 216 then        '2.16s, time to toggle the step pin.
  StepTicks = 0
  Toggle StepPin
Endif

RESUME
ENABLE

Main:

'---------------------------------------------
'Your main code here.......
'remember, NO time consuming commands, like Pause, sleep, nap etc.
'----------------------------------------------
Goto Main

This is completely untested and just something to show you one approach. Also, I suggest you'll have a look at Darrel Taylors Instant Interrupts, search the forum, it makes interrupts a breeze but MAY be overkill in this application.

About that LCD, if your connections ARE fine and matches your DEFINES then the only thing I can think of is a longer pause at the beginning OR you could try to increase the command and data delay with:

DEFINE LCD_COMMANDUS 2000    '<-----Increase this...
DEFINE LCD_DATAUS 50             '<----and this.

/Henrik Olsson.