PIC18F258 MICROCHIP [Microchip Technology], PIC18F258 Datasheet - Page 120

• Manufacturer Part Number: PIC18F258
• Description: High Performance, 28/40-Pin Enhanced FLASH Microcontrollers with CAN
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18FXX8
14.1
Timer3 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 clock select
bit, TMR3CS (T3CON register).
FIGURE 14-1:
FIGURE 14-2:
DS41159B-page 118
Note 1: When enable bit T1OSCEN is cleared, the inverter and feedback resistor are turned off. This eliminates power drain.
Note 1: When the T1OSCEN bit is cleared, the inverter and feedback resistor are turned off. This eliminates power drain.
TMR3IF Overflow
Interrupt Flag
bit
T1OSO/
T13CKI
T1OSI
Timer3 Operation
T1OSO/
T13CKI
T1OSI
Data Bus<7:0>
Write TMR3L
Read TMR3L
TMR3IF
Overflow
Interrupt
Flag bit
TIMER3 BLOCK DIAGRAM
TIMER3 BLOCK DIAGRAM CONFIGURED IN 16-BIT READ/WRITE MODE
T1OSC
8
TMR3H
T1OSC
TMR3H
TMR3H
8
To Timer1 Clock Input
Oscillator
Enable
T1OSCEN
8
TMR3
TMR3L
Oscillator
T1OSCEN
Enable
(1)
8
TMR3L
CLR
(1)
Preliminary
Clock
Internal
F
CLR
OSC
/4
TMR3ON
On/Off
Clock
F
Internal
TMR3CS
OSC
When TMR3CS = 0, Timer3 increments every instruc-
tion cycle. When TMR3CS = 1, Timer3 increments on
every rising edge of the Timer1 external clock input, or
the Timer1 oscillator, if enabled.
When the Timer1 oscillator is enabled (T1OSCEN is set),
the RC1/T1OSI and RC0/T1OSO/T1CKI pins become
inputs. That is, the TRISC<1:0> value is ignored.
Timer3 also has an internal “RESET input”. This
RESET can be generated by the CCP module
(Section 15.1).
1
0
/4
TMR3ON
T3CCPx
CCP Special Trigger
On/Off
TMR3CS
T3CKPS1:T3CKPS0
1
0
T3SYNC
Prescaler
1, 2, 4, 8
T3CCPx
CCP Special Trigger
T3CKPS1:T3CKPS0
0
1
2
T3SYNC
Prescaler
1, 2, 4, 8
0
1
 2002 Microchip Technology Inc.
2
Synchronized
Clock Input
Synchronize
SLEEP Input
Synchronized
det
Clock Input
Synchronize
SLEEP Input
det