PIC16LC773I/SO View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC16LC773I/SO

28/40-Pin, 8-Bit CMOS Microcontrollers w/ 12-Bit A/D

Microchip Technology 

PIC16C77X

12.12 Watchdog Timer (WDT)

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

oscillator which does not require any external compo-

nents. This RC oscillator is separate from the RC oscil-

lator of the OSC1/CLKIN pin. That means that 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 12.1).

WDT time-out period values may be found in the Elec-

trical Specifications section under parameter #31. Val-

ues for the WDT prescaler may be assigned using the

OPTION_REG register.

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.

FIGURE 12-12: WATCHDOG TIMER BLOCK DIAGRAM

From TMR0 Clock Source

(Figure 4-2)

WDT Timer

0

1

M

U

X

Postscaler

8

WDT

Enable Bit

PSA

8 - to - 1 MUX

PS2:PS0

To TMR0 (Section 4-2)

0

1

MUX

PSA

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

WDT

Time-out

FIGURE 12-13: SUMMARY OF WATCHDOG TIMER REGISTERS

Address Name

Bit 7

Bit 6

Bit 5 Bit 4

Bit 3

2007h

Config. bits

(1)

BODEN(1) CP1 CP0 PWRTE(1)

81h,181h OPTION_REG RBPU INTEDG T0CS T0SE

PSA

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

Note 1: See Figure 12-1 for the full description of the configuration word bits.

Bit 2

WDTE

PS2

Bit 1

FOSC1

PS1

Bit 0

FOSC0

PS0

 1999-2013 Microchip Technology Inc.

Advance Information

DS30275B-page 139

Share Link: