DM163006 datasheet(210/320 Pages) MICROCHIP

210 / 320 page

PIC18C601/801

DS39541A-page 210

Advance Information

 2001 Microchip Technology Inc.

19.2

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/CLKI pin. That means that the WDT will run,

even if the clock on the OSC1/CLKI and OSC2/CLKO

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 RCON register

will be cleared upon a WDT time-out.

By default, the Watchdog Timer is disabled by configu-

ration to allow software control over Watchdog Timer

operation. If the WDT is enabled by configuration, soft-

ware execution may not disable this function. When the

Watchdog Timer is disabled by configuration, the

SWDTEN bit in the WDTCON register enables/

disables the operation of the WDT.

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

Electrical Specifications section under parameter #31.

Values for the WDT postscaler may be assigned by

using configuration bits WDPS<3:1> in CONFIG2H

ration, values for the WDT postscaler may be assigned

using the SWDPS bits in the WDTCON register.

19.2.1

CONTROL REGISTER

readable and writable register. It contains control bits to

control the Watchdog Timer from user software. If the

Watchdog Timer is enabled by configuration, this regis-

ter setting is ignored.

WDTCON REGISTER

Note 1: 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.

2: 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.

U-0

R/W-0

—

SWDPS2

SWDPS1

SWDPS0 SWDTEN

bit 7

bit 0

bit 7-4

Unimplemented: Read as ’0’

bit 3-1

SWDPS2:SWDPS0: Software Watchdog Timer Postscale Select bits

111

= 1:128

110

= 1:64

101

= 1:32

100

= 1:16

011

= 1:8

010

= 1:4

001

= 1:2

000

= 1:1

bit 0

SWDTEN: Software Controlled Watchdog Timer Enable bit

= Watchdog Timer is on

= Watchdog Timer is turned off if it is not disabled

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

DM163006 Datasheet(PDF) 210 Page - Microchip Technology

DM163006 Datasheet(HTML) 210 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL