PIC18F1XK22 Datasheet, PDF (102/388 Pages) Microchip Technology – 20-Pin Flash Microcontrollers with nanoWatt XLP Technology

PIC18F1XK22/LF1XK22
10.1 Timer1 Operation
Timer1 can operate in one of the following modes:
• Timer
• Synchronous Counter
• Asynchronous Counter
The operating mode is determined by the clock select
bit, TMR1CS of the T1CON register. When TMR1CS is
cleared (= 0), Timer1 increments on every internal
instruction cycle (FOSC/4). When the bit is set, Timer1
increments on every rising edge of either the Timer1
external clock input or the Timer1 oscillator, if enabled.
When the Timer1 oscillator is enabled, the digital
circuitry associated with the OSC1 and OSC2 pins is
disabled. This means the values of TRISA<5:4> are
ignored and the pins are read as ‘0’.
FIGURE 10-1:
TIMER1 BLOCK DIAGRAM
Timer1 Oscillator
Timer1 Clock Input
On/Off
1
OSC1/T13CKI
OSC2
INTOSC
Without CLKOUT
T1OSCEN⁽¹⁾
1
FOSC/4
Internal
Clock
0
TMR1CS
Prescaler
1, 2, 4, 8
2
Synchronize
Detect
0
Sleep Input
T1CKPS<1:0>
T1SYNC
TMR1ON
Timer1
On/Off
Clear TMR1
(CCP Special Event Trigger)
TMR1L
TMR1
High Byte
Set
TMR1IF
on Overflow
Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain.
DS41365D-page 102
Preliminary
 2010 Microchip Technology Inc.