PIC18F1230 MICROCHIP [Microchip Technology], PIC18F1230 Datasheet - Page 108

• Manufacturer Part Number: PIC18F1230
• Description: 18/20/28-Pin, Enhanced Flash Microcontrollers with nanoWatt Technology, High-Performance PWM and A/D
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18F1230/1330
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:
DS39758B-page 106
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/T1CKI
Timer1 Operation
T1OSO/T1CKI
Data Bus<7:0>
Write TMR1L
Read TMR1L
TMR1IF
Overflow
Interrupt
Flag bit
TMR1IF
Overflow
Interrupt
Flag Bit
T1OSI
T1OSI
TIMER1 BLOCK DIAGRAM
TIMER1 BLOCK DIAGRAM: 16-BIT READ/WRITE MODE
8
High Byte
T1OSC
TMR1H
T1OSC
8
Timer1
TMR1H
8
TMR1
TMR1
T1OSCEN
Enable
Oscillator
T1OSCEN
Enable
Oscillator
TMR1L
Advance Information
TMR1L
8
(1)
(1)
Clock
Internal
F
OSC
F
Internal
Clock
OSC
/4
TMR1ON
On/Off
/4
TMR1CS
When TMR1CS = 0, Timer1 increments every
instruction 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 T1OSI and T1OSO/T1CKI pins become
inputs. That is, the corresponding TRISA bit value is
ignored, and the pins are read as ‘0’.
TMR1ON
On/Off
1
0
TMR1CS
1
0
T1CKPS1:T1CKPS0
T1CKPS1:T1CKPS0
T1SYNC
Prescaler
1, 2, 4, 8
T1SYNC
Prescaler
0
1
1, 2, 4, 8
2
0
1
2
© 2006 Microchip Technology Inc.
Synchronized
Clock Input
Peripheral Clocks
Synchronized
Synchronize
Clock Input
Peripheral Clocks
Synchronize
det
det