PIC12F635/PIC16F636/639
6.0
TIMER1 MODULE WITH GATE
CONTROL
The Timer1 module is a 16-bit timer/counter with the
following features:
• 16-bit timer/counter register pair (TMR1H:TMR1L)
• Programmable internal or external clock source
• 3-bit prescaler
• Optional LP oscillator
• Synchronous or asynchronous operation
• Timer1 gate (count enable) via comparator or
T1G pin
• Interrupt on overflow
• Wake-up on overflow (external clock,
Asynchronous mode only)
• Comparator output synchronization to Timer1
clock
Figure 6-1 is a block diagram of the Timer1 module.
6.1
Timer1 Operation
The Timer1 module is a 16-bit incrementing counter
which is accessed through the TMR1H:TMR1L register
pair. Writes to TMR1H or TMR1L directly update the
counter.
When used with an internal clock source, the module is
a timer. When used with an external clock source, the
module can be used as either a timer or counter.
6.2
Clock Source Selection
The TMR1CS bit of the T1CON register is used to select
the clock source. When TMR1CS = 0, the clock source
is FOSC/4. When TMR1CS = 1, the clock source is
supplied externally.
Clock
Source
FOSC
Mode
T1OSCEN
T1CS
FOSC/4
x
x
1
xxx
x
1
T1CKI pin
T1LPOSC
LP or
INTOSCIO
DS41232D-page 64
© 2007 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
