PIC16F688
6.7
Timer1 Interrupt
6.8
Timer1 Operation During Sleep
The Timer1 register pair (TMR1H:TMR1L) increments
to FFFFh and rolls over to 0000h. When Timer1 rolls
over, the Timer1 interrupt flag bit of the PIR1 register is
set. To enable the interrupt on rollover, you must set
these bits:
Timer1 can only operate during Sleep when setup in
Asynchronous Counter mode. In this mode, an external
crystal or clock source can be used to increment the
counter. To set up the timer to wake the device:
• TMR1ON bit of the T1CON register must be set
• TMR1IE bit of the PIE1 register must be set
• PEIE bit of the INTCON register must be set
• Timer1 interrupt enable bit of the PIE1 register
• PEIE bit of the INTCON register
• GIE bit of the INTCON register
The device will wake-up on an overflow and execute
the next instruction. If the GIE bit of the INTCON
register is set, the device will call the Interrupt Service
Routine (0004h).
The interrupt is cleared by clearing the TMR1IF bit in
the Interrupt Service Routine.
Note:
The TMR1H:TTMR1L register pair and the
TMR1IF bit should be cleared before
enabling interrupts.
FIGURE 6-2:
TIMER1 INCREMENTING EDGE
T1CKI = 1
when TMR1
Enabled
T1CKI = 0
when TMR1
Enabled
Note 1: Arrows indicate counter increments.
2: In Counter mode, a falling edge must be registered by the counter prior to the first incrementing rising edge of
the clock.
DS41203D-page 50
© 2007 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
