PIC16C711-04SS 데이터 시트보기 (PDF) - Microchip Technology

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PIC16C711-04SS

8-Bit CMOS Microcontrollers with A/D Converter

Microchip Technology 

PIC16C71X

6.3 Prescaler

An 8-bit counter is available as a prescaler for the

Timer0 module, or as a postscaler for the Watchdog

Timer, respectively (Figure 6-6). For simplicity, this

counter is being referred to as “prescaler” throughout

this data sheet. Note that there is only one prescaler

available which is mutually exclusively shared between

the Timer0 module and the Watchdog Timer. Thus, a

prescaler assignment for the Timer0 module means

that there is no prescaler for the Watchdog Timer, and

vice-versa.

The PSA and PS2:PS0 bits (OPTION<3:0>) determine

the prescaler assignment and prescale ratio.

When assigned to the Timer0 module, all instructions

writing to the TMR0 register (e.g. CLRF 1, MOVWF 1,

BSF 1,x....etc.) will clear the prescaler. When

assigned to WDT, a CLRWDT instruction will clear the

prescaler along with the Watchdog Timer. The pres-

caler is not readable or writable.

Note:

Writing to TMR0 when the prescaler is

assigned to Timer0 will clear the prescaler

count, but will not change the prescaler

assignment.

FIGURE 6-6: BLOCK DIAGRAM OF THE TIMER0/WDT PRESCALER

CLKOUT (=Fosc/4)

RA4/T0CKI

pin

T0SE

0M

U

X

1

T0CS

1

M

0

U

X

PSA

SYNC

2

Cycles

Data Bus

8

TMR0 reg

Set flag bit T0IF

on Overflow

Watchdog

Timer

WDT Enable bit

0

M

U

1X

PSA

8-bit Prescaler

8

8 - to - 1MUX

0

1

MUX

WDT

Time-out

Note: T0CS, T0SE, PSA, PS2:PS0 are (OPTION<5:0>).

PS2:PS0

PSA

DS30272A-page 34

© 1997 Microchip Technology Inc.

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