PIC14000 datasheet(87/153 Pages) MICROCHIP

87 / 153 page

Preliminary

DS40122B-page 87

PIC14000

10.8.1

SLEEP MODE

The SLEEP mode is entered by executing a SLEEP

instruction.

If SLEEP mode is enabled, the WDT will be cleared but

keep running. The PD bit in the STATUS register is

cleared, the TO bit is set, and on-chip oscillators are

shut off, except the WDT RC oscillator, which continues

to run. The I/O ports maintain the status they had

before the SLEEP command was executed (driving

high, low, or high-impedance).

It is an option while in SLEEP mode to leave the

on-chip oscillator running. This option allows an A/D

conversion to continue while the CPU is in SLEEP

mode. The CPU clocks are stopped in this condition to

preserve power. The operation of the on-chip oscillator

during

SLEEP

controlled

OSCOFF

(SLPCON<3>). Clearing this bit to ‘0’ allows the oscil-

lator to continue to run. This bit is only active in SLEEP

mode.

For lowest power consumption in this mode, all I/O pins

should be either at VDD or VSS with no external circuitry

drawing current from the I/O pin. I/O pins that are

high-impedance inputs should be pulled high or low

externally to avoid leakage currents caused by ﬂoating

inputs. The MCLR pin must be at a logic high level

(VIH). The contribution from any on-chip pull-up

resistors should be considered.

10.8.2

WAKE-UP FROM SLEEP

The PIC14000 can wake up from SLEEP through one

of the following events:

External reset input on MCLR pin

Watchdog Timer time-out (if WDT is enabled)

Interrupt from OSC1/PBTN pin

RC<7:4> port change

I2C (serial port) start/stop bit detect interrupt.

Wake-up on programmable reference compara-

tor interrupt.

A/D conversion complete (comparator trip) inter-

rupt.

A/D timer overﬂow interrupt.

An external reset on MCLR pin causes a device reset.

The

other

wake-up

events

are

considered

continuation of program execution. The TO and PD bits

in the STATUS register can be used to determine the

cause of device reset. The PD bit, which is set on

power-up is cleared when SLEEP is invoked. The TO

bit is cleared if a WDT time-out occurred (and caused

a wake-up).

When the SLEEP instruction is being executed, the next

instruction (PC + 1) is pre-fetched. For the device to

wake-up through an interrupt event, the corresponding

interrupt enable bit must be set. Wake-up occurs

regardless of the state of bit GIE. If bit GIE is clear, the

device continues execution at the instruction after the

SLEEP

instruction. If bit GIE is set, the device executes

the instruction after the SLEEP instruction and then

branches to the interrupt address (0004h). In cases

where the execution of the instruction following SLEEP

is not desirable, the user should have a NOP after the

SLEEP

instruction.

The WDT is cleared when the device wakes-up from

sleep, regardless of the source of wake-up.

Note:

If the global interrupts are disabled (GIE is

cleared), but any interrupt source has both

its

interrupt

enable

bit

and

the

corresponding interrupt ﬂag bits set, the

device will immediately wake from SLEEP.

10.8.3

HIBERNATE MODE

HIBERNATE mode is an extension of SLEEP mode

with the following additions.

• WDT is forced off

• Weak pull-ups on RC<5:0> are disabled

• Some input buffers are gated-off (refer to

Section 5.0)

The HIBERNATE mode is entered by executing a

SLEEP

instruction with HIBEN (SLPCON<7>) bit set.

The PIC14000 wakes up from HIBERNATE mode via

all the same mechanisms as SLEEP mode, except for

WDT time-out. HIBERNATE mode allows power con-

sumption to be reduced to a minimum.

PIC14000 Datasheet(PDF) 87 Page - Microchip Technology

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