PIC18F258-ESLASHSOSQTP datasheet(115/402 Pages) MICROCHIP

115 / 402 page

DS41159E-page 113

PIC18FXX8

12.0

TIMER1 MODULE

The Timer1 module timer/counter has the following

features:

• 16-bit timer/counter

(two 8-bit registers: TMR1H and TMR1L)

• Readable and writable (both registers)

• Internal or external clock select

• Interrupt-on-overflow from FFFFh to 0000h

• Reset from CCP module special event trigger

module, as well as contains the Timer1 Oscillator

Enable bit (T1OSCEN). Timer1 can be enabled/

disabled by setting/clearing control bit, TMR1ON

(T1CON register).

Figure 12-1 is a simplified block diagram of the Timer1

module.

T1CON: TIMER1 CONTROL REGISTER

Note:

Timer1 is disabled on POR.

R/W-0

U-0

R/W-0

RD16

—

T1CKPS1 T1CKPS0 T1OSCEN

T1SYNC

TMR1CS

TMR1ON

bit 7

bit 0

bit 7

RD16: 16-bit Read/Write Mode Enable bit

= Enables register read/write of Timer1 in one 16-bit operation

= Enables register read/write of Timer1 in two 8-bit operations

bit 6

Unimplemented: Read as ‘0’

bit 5-4

T1CKPS1:T1CKPS0: Timer1 Input Clock Prescale Select bits

= 1:8 Prescale value

= 1:4 Prescale value

= 1:2 Prescale value

= 1:1 Prescale value

bit 3

T1OSCEN: Timer1 Oscillator Enable bit

= Timer1 oscillator is enabled

= Timer1 oscillator is shut-off

The oscillator inverter and feedback resistor are turned off to eliminate power drain.

bit 2

T1SYNC: Timer1 External Clock Input Synchronization Select bit

When TMR1CS = 1:

= Do not synchronize external clock input

= Synchronize external clock input

When TMR1CS = 0:

This bit is ignored. Timer1 uses the internal clock when TMR1CS = 0.

bit 1

TMR1CS: Timer1 Clock Source Select bit

= External clock from pin RC0/T1OSO/T1CKI (on the rising edge)

= Internal clock (FOSC/4)

bit 0

TMR1ON: Timer1 On bit

= Enables Timer1

= Stops Timer1

Legend:

R = Readable bit

W = Writable bit

U = Unimplemented bit, read as ‘0’

-n = Value at POR

‘1’ = Bit is set

‘0’ = Bit is cleared

x = Bit is unknown

PIC18F258-E/SOSQTP 数据表(PDF) 115 Page - Microchip Technology

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