Interrupt problem.

[Bruce]

Hi Peter,

Looks like you're reloading timer1 before it can over-flow (not sure without knowing the osc speed), but try something like this.

PRESET  VAR WORD
ELAPSED VAR BYTE
PRESET = 12000 

    T1CON=%00110000  ' Set timer1 prescaler as 1:8
    PIR1.0=0	       ' Clear timer1 overflow flag		
    PIE1=%00000001      ' Enable interrupt on timer1 overflow	
    TMR1H=PRESET.highbyte  ' Load timer1 high byte
    TMR1L=PRESET.Lowbyte  ' Load timer1 low byte
    T1CON.0=1               ' Turm on timer1
    INTCON=%11000000   ' Global & peripheral interrupts enabled
  	
    ON INTERRUPT goto TICKER
    
MAINLOOP:
    TOGGLE PORTB.5
    ELAPSED = ELAPSED + 1
    GOTO MAINLOOP
    
    DISABLE
TICKER:
    TOGGLE PORTB.0          ' Toggle PORTB.0
    TMR1H = PRESET.highbyte ' Load timer1 high byte
    TMR1L = PRESET.Lowbyte  ' Load timer1 low byte
    PIR1.0=0                ' Clear TMR1 overflow flag
    RESUME
    ENABLE

    END

HTH....;o}