PIC18F6620 Microchip, PIC18F6620 Datasheet - Page 138

• Manufacturer Part Number: PIC18F6620
• Description: Microcontroller
• Manufacturer: Microchip

PIC18F6520/8520/6620/8620/6720/8720
12.1
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 clock select
bit, TMR1CS (T1CON<1>).
FIGURE 12-1:
FIGURE 12-2:
DS39609B-page 136
Note 1: When enable bit T1OSCEN is cleared, the inverter and feedback resistor are turned off. This eliminates power drain.
Note 1: When enable bit T1OSCEN is cleared, the inverter and feedback resistor are turned off. This eliminates power drain.
T1OSO/T13CKI
T1OSO/T13CKI
Timer1 Operation
TMR1IF
Overflow
Interrupt
Flag Bit
TMR1IF
Overflow
Interrupt
Flag bit
Data Bus<7:0>
Write TMR1L
Read TMR1L
T1OSI
T1OSI
TIMER1 BLOCK DIAGRAM
TIMER1 BLOCK DIAGRAM: 16-BIT READ/WRITE MODE
8
TMR1H
T1OSC
T1OSC
High Byte
TMR1H
Timer 1
8
8
TMR1
T1OSCEN
Enable
Oscillator
TMR1
TMR1L
Oscillator
Enable
T1OSCEN
CLR
TMR1L
(1)
8
(1)
Clock
Internal
F
CLR
OSC
/4
TMR1ON
CCP Special Event Trigger
On/Off
Clock
F
Internal
TMR1CS
OSC
1
0
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 and RC0/T1OSO/T13CKI 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 16.0 “Capture/Compare/PWM (CCP)
Modules”).
/4
TMR1ON
CCP Special Event Trigger
On/Off
T1CKPS1:T1CKPS0
TMR1CS
1
0
T1SYNC
Prescaler
1, 2, 4, 8
0
1
T1CKPS1:T1CKPS0
2
T1SYNC
Prescaler
1, 2, 4, 8
1
0
2
 2004 Microchip Technology Inc.
Synchronized
Clock Input
Synchronize
Sleep Input
Synchronized
det
Clock Input
Synchronize
Sleep Input
det