PIC16LC62B-04SLASHP datasheet(64/120 Pages) MICROCHIP

64 / 120 page

PIC16C62B/72A

DS35008B-page 64

Preliminary

10.12

Watchdog Timer (WDT)

The Watchdog Timer is a free running on-chip RC oscil-

lator which does not require any external components.

This RC oscillator is separate from the RC oscillator of

the OSC1/CLKIN pin. The WDT will run, even if the

clock on the OSC1/CLKIN and OSC2/CLKOUT pins of

the device has been stopped, for example, by execution

of a SLEEP instruction.

During normal operation, a WDT time-out generates a

device RESET (Watchdog Timer Reset). If the device is

in SLEEP mode, a WDT time-out causes the device to

wake-up and continue with normal operation (Watch-

dog Timer Wake-up). The TO bit in the STATUS register

will be cleared upon a Watchdog Timer time-out.

The WDT can be permanently disabled by clearing

configuration bit WDTE (Section 10.1).

The WDT time-out period (TWDT, parameter #31) is

multiplied by the prescaler ratio, when the prescaler is

assigned to the WDT. The prescaler assignment

(assigned to either the WDT or Timer0) and prescaler

ratio are set in the OPTION_REG register.

FIGURE 10-8: WATCHDOG TIMER BLOCK DIAGRAM

FIGURE 10-9: SUMMARY OF WATCHDOG TIMER REGISTERS

Note:

The CLRWDT and SLEEP instructions clear

the WDT and the postscaler, if assigned to

the WDT, and prevent it from timing out and

generating a device RESET condition.

Note:

When a CLRWDT instruction is executed

and the prescaler is assigned to the WDT,

the prescaler count will be cleared, but the

prescaler assignment is not changed.

Address

Name

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

2007h

Config. bits

BODEN

CP1

CP0

PWRTE

WDTE

FOSC1

FOSC0

81h

OPTION_REG

RBPU

INTEDG

T0CS

T0SE

PSA

PS2

PS1

PS0

Legend: Shaded cells are not used by the Watchdog Timer.

From TMR0 Clock Source

(Figure 4-2)

To TMR0 (Figure 4-2)

Postscaler

WDT Timer

WDT

Enable Bit

PSA

8 - to - 1 MUX

PS2:PS0

MUX

PSA

WDT

Time-out

Note: PSA and PS2:PS0 are bits in the OPTION_REG register.

PIC16LC62B-04/P Datasheet(PDF) 64 Page - Microchip Technology

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