PIC18F2331-E/ML MICROCHIP [Microchip Technology], PIC18F2331-E/ML Datasheet - Page 132

• Manufacturer Part Number: PIC18F2331-E/ML
• Description: 28/40/44-Pin Enhanced Flash Microcontrollers with nanoWatt Technology, High-Performance PWM and A/D
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18F2331/2431/4331/4431
13.1
Timer1 can operate in one of these modes:
• As a timer
• As a synchronous counter
• As an asynchronous counter
The operating mode is determined by the Timer1 Clock
Select bit, TMR1CS (T1CON<1>).
FIGURE 13-1:
FIGURE 13-2:
DS39616D-page 132
Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain.
Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain.
T1OSO/T1CKI
T1OSO/T1CKI
Timer1 Operation
T1OSI
T1OSI
Timer1 Oscillator
Timer1 Oscillator
T1OSCEN
T1OSCEN
T1CKPS<1:0>
T1SYNC
TMR1ON
T1CKPS<1:0>
T1SYNC
TMR1ON
TIMER1 BLOCK DIAGRAM
TIMER1 BLOCK DIAGRAM (16-BIT READ/WRITE MODE)
(1)
(1)
TMR1CS
TMR1CS
(CCP Special Event Trigger)
Clear TMR1
(CCP Special Event Trigger)
Clear TMR1
Clock
Clock
F
Internal
Internal
F
OSC
OSC
/4
/4
On/Off
1
0
1
0
Timer1 Clock Input
Timer1 Clock Input
Prescaler
Prescaler
1, 2, 4, 8
When TMR1CS = 0, Timer1 increments every instruc-
tion cycle. When TMR1CS = 1, Timer1 increments on
every rising edge of the external clock input or the
Timer1 oscillator, if enabled.
When the Timer1 oscillator is enabled (T1OSCEN is
set), the RC1/T1OSI/CCP2/FLTA and RC0/T1OSO/
T1CKI pins become inputs. That is, the TRISC<1:0>
value is ignored and the pins are read as ‘0’.
Timer1 also has an internal “Reset input”. This Reset
can be generated by the CCP module (see
Section 16.4.4 “Special Event
1, 2, 4, 8
2
2
TMR1L
TMR1L
8
Sleep Input
Synchronize
Sleep Input
8
Synchronize
Detect
Detect
High Byte
High Byte
TMR1H
TMR1
TMR1
8
 2010 Microchip Technology Inc.
8
8
Trigger”).
Internal Data Bus
1
0
1
0
Read TMR1L
Write TMR1L
Set
TMR1IF
on Overflow
Set
TMR1IF
on Overflow
Timer1
Timer1
On/Off
On/Off