PIC12F519-ESLASHMS datasheet(49/96 Pages) MICROCHIP

49 / 96 page

DS41319B-page 47

PIC12F519

8.7

Time-out Sequence, Power-down

and Wake-up from Sleep Status

Bits (TO, PD, GPWUF)

The TO, PD and (GPWUF) bits in the STATUS register

can be tested to determine if a Reset condition has

been caused by a power-up condition, a MCLR or

Watchdog Timer (WDT) Reset.

TABLE 8-7:

TO/PD/(GPWUF) STATUS

AFTER RESET

8.8

Power-down Mode (Sleep)

A device may be powered down (Sleep) and later

powered up (wake-up from Sleep).

8.8.1

SLEEP

The Power-down mode is entered by executing a

SLEEP

instruction.

If enabled, the Watchdog Timer will be cleared but

keeps running, the TO bit (STATUS<4>) is set, the PD

bit (STATUS<3>) is cleared and the oscillator driver is

turned off. The I/O ports maintain the status they had

before the SLEEP instruction was executed (driving

high, driving low or high-impedance).

For lowest current consumption while powered down,

the T0CKI input should be at VDD or VSS and the

GP3/MCLR/VPP pin must be at a logic high level if

MCLR is enabled.

8.8.2

WAKE-UP FROM SLEEP

The device can wake-up from Sleep through one of the

following events:

An external Reset input on GP3/MCLR/VPP pin,

when configured as MCLR.

A Watchdog Timer Time-out Reset (if WDT was

enabled).

A change on input pin GP0, GP1 and GP3 when

wake-up on change is enabled.

These events cause a device Reset. The TO, PD and

GPWUF bits can be used to determine the cause of

device Reset. The TO bit is cleared if a WDT time-out

occurred (and caused wake-up). The PD bit, which is

set on power-up, is cleared when SLEEP is invoked.

The GPWUF bit indicates a change in state while in

Sleep at pins GP0, GP1 and GP3 (since the last file or

bit operation on GPIO port).

The WDT is cleared when the device wakes from

Sleep, regardless of the wake-up source.

GPWUF

Reset Caused By

WDT wake-up from Sleep

WDT time-out (not from

Sleep)

MCLR wake-up from Sleep

Power-up

MCLR not during Sleep

Wake-up from Sleep on pin

change

Legend: u

= unchanged

Note 1:

The TO, PD and GPWUF bits maintain

their status (u) until a Reset occurs. A

low-pulse on the MCLR input does not

change the TO, PD and GPWUF Status

bits.

Note:

A Reset generated by a WDT time-out

does not drive the MCLR pin low.

Note:

Caution:

Right before entering Sleep,

read the input pins. When in Sleep, wake

up occurs when the values at the pins

change from the state they were in at the

last reading. If a wake-up on change

occurs and the pins are not read before

re-entering Sleep, a wake-up will occur

immediately even if no pins change while

in Sleep mode.

PIC12F519-E/MS Datasheet(PDF) 49 Page - Microchip Technology

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