PIC18F258-ESLASHSOSQTP datasheet(121/402 Pages) MICROCHIP

121 / 402 page

DS41159E-page 119

PIC18FXX8

14.0

TIMER3 MODULE

The Timer3 module timer/counter has the following

features:

• 16-bit timer/counter

(two 8-bit registers: TMR3H and TMR3L)

• Readable and writable (both registers)

• Internal or external clock select

• Interrupt-on-overflow from FFFFh to 0000h

• Reset from CCP1/ECCP1 module trigger

Figure 14-1 is a simplified block diagram of the Timer3

module.

module and sets the CCP1 and ECCP1 clock source.

module, as well as contains the Timer1 Oscillator

Enable bit (T1OSCEN) which can be a clock source for

Timer3.

T3CON:TIMER3 CONTROL REGISTER

Note:

Timer3 is disabled on POR.

R/W-0

RD16

T3ECCP1 T3CKPS1 T3CKPS0

T3CCP1

T3SYNC

TMR3CS

TMR3ON

bit 7

bit 0

bit 7

RD16: 16-bit Read/Write Mode Enable bit

= Enables register read/write of Timer3 in one 16-bit operation

= Enables register read/write of Timer3 in two 8-bit operations

bit 6,3

T3ECCP1:T3CCP1: Timer3 and Timer1 to CCP1/ECCP1 Enable bits

= Timer3 is the clock source for compare/capture CCP1 and ECCP1 modules

= Timer3 is the clock source for compare/capture of ECCP1,

Timer1 is the clock source for compare/capture of CCP1

= Timer1 is the clock source for compare/capture CCP1 and ECCP1 modules

bit 5-4

T3CKPS1:T3CKPS0: Timer3 Input Clock Prescale Select bits

= 1:8 Prescale value

= 1:4 Prescale value

= 1:2 Prescale value

= 1:1 Prescale value

bit 2

T3SYNC: Timer3 External Clock Input Synchronization Control bit

(Not usable if the system clock comes from Timer1/Timer3.)

When TMR3CS = 1:

= Do not synchronize external clock input

= Synchronize external clock input

When TMR3CS = 0:

This bit is ignored. Timer3 uses the internal clock when TMR3CS = 0.

bit 1

TMR3CS: Timer3 Clock Source Select bit

= External clock input from Timer1 oscillator or T1CKI (on the rising edge after the first falling edge)

= Internal clock (FOSC/4)

bit 0

TMR3ON: Timer3 On bit

= Enables Timer3

= Stops Timer3

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) 121 Page - Microchip Technology

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