PIC16F18323-ESLASHRFQTP datasheet(105/442 Pages) MICROCHIP

105 / 442 page

 2015 Microchip Technology Inc.

Preliminary

DS40001799A-page 105

PIC16(L)F18313/18323

9.0

WATCHDOG TIMER (WDT)

The Watchdog Timer is a system timer that generates

a Reset if the firmware does not issue a CLRWDT

instruction within the time-out period. The Watchdog

Timer is typically used to recover the system from

unexpected events.

The WDT has the following features:

• Independent clock source

• Multiple operating modes

- WDT is always on

- WDT is off when in Sleep

- WDT is controlled by software

- WDT is always off

• Configurable time-out period is from 1 ms to 256

seconds (nominal)

• Multiple Reset conditions

• Operation during Sleep

FIGURE 9-1:

WATCHDOG TIMER BLOCK DIAGRAM

9.1

Independent Clock Source

The WDT derives its time base from the 31 kHz

LFINTOSC internal oscillator. Time intervals in this

chapter are based on a nominal interval of 1 ms. See

Table 34-8 for the LFINTOSC specification.

9.2

WDT Operating Modes

The Watchdog Timer module has four operating modes

controlled by the WDTE<1:0> bits in Configuration

Words. See Table 9-1.

9.2.1

WDT IS ALWAYS ON

When the WDTE bits of Configuration Words are set to

‘11’, the WDT is always on.

WDT protection is active during Sleep.

9.2.2

WDT IS OFF IN SLEEP

When the WDTE bits of Configuration Words are set to

‘10’, the WDT is on, except in Sleep.

WDT protection is not active during Sleep.

9.2.3

WDT CONTROLLED BY SOFTWARE

When the WDTE bits of Configuration Words are set to

‘01’, the WDT is controlled by the SWDTEN bit of the

WDTCON register.

WDT protection is unchanged by Sleep. See Table 9-1

for more details.

TABLE 9-1:

WDT OPERATING MODES

LFINTOSC

23-bit Programmable

Prescaler WDT

WDT Time-out

WDTPS<4:0>

SWDTEN

Sleep

WDTE<1:0> = 11

WDTE<1:0> = 01

WDTE<1:0> = 10

WDTE<1:0>

SWDTEN

Device

Mode

WDT

Mode

XActive

Awake Active

Sleep Disabled

Active

Disabled

XDisabled

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