DSPIC33FJ32GP302THSLASHSP datasheet(153/403 Pages) MICROCHIP

153 / 403 page

 2009 Microchip Technology Inc.

Preliminary

DS70292D-page 153

dsPIC33FJ32GP302/304, dsPIC33FJ64GPX02/X04, AND dsPIC33FJ128GPX02/X04

10.0

POWER-SAVING FEATURES

The dsPIC33FJ32GP302/304, dsPIC33FJ64GPX02/

X04, and dsPIC33FJ128GPX02/X04 devices provide

the ability to manage power consumption by selectively

managing clocking to the CPU and the peripherals. In

general, a lower clock frequency and a reduction in the

number of circuits being clocked constitutes lower

consumed

power.

dsPIC33FJ32GP302/304,

dsPIC33FJ64GPX02/X04, and dsPIC33FJ128GPX02/

X04 devices can manage power consumption in four

ways:

• Clock frequency

• Instruction-based Sleep and Idle modes

• Software-controlled Doze mode

• Selective peripheral control in software

Combinations of these methods can be used to selec-

tively tailor an application’s power consumption while

still maintaining critical application features, such as

timing-sensitive communications.

10.1

Clock Frequency and Clock

Switching

dsPIC33FJ32GP302/304,

dsPIC33FJ64GPX02/X04,

and dsPIC33FJ128GPX02/X04 devices allow a wide

range of clock frequencies to be selected under

application control. If the system clock configuration is

not locked, users can choose low-power or high-

precision oscillators by simply changing the NOSC bits

(OSCCON<10:8>). The process of changing a system

clock during operation, as well as limitations to the

process, are discussed in more detail in Section 9.0

“Oscillator Configuration”.

10.2

Instruction-Based Power-Saving

Modes

dsPIC33FJ32GP302/304,

dsPIC33FJ64GPX02/X04,

and dsPIC33FJ128GPX02/X04 devices have two

special power-saving modes that are entered through

the execution of a special PWRSAV instruction. Sleep

mode stops clock operation and halts all code

execution. Idle mode halts the CPU and code

execution, but allows peripheral modules to continue

operation. The assembler syntax of the PWRSAV

instruction is shown in Example 10-1.

Sleep and Idle modes can be exited as a result of an

enabled interrupt, WDT time-out or a device Reset. When

the device exits these modes, it is said to wake up.

10.2.1

SLEEP MODE

The following occur in Sleep mode:

• The system clock source is shut down. If an

on-chip oscillator is used, it is turned off.

• The device current consumption is reduced to a

minimum, provided that no I/O pin is sourcing

current.

• The Fail-Safe Clock Monitor does not operate,

since the system clock source is disabled.

• The LPRC clock continues to run in Sleep mode if

the WDT is enabled.

• The WDT, if enabled, is automatically cleared

prior to entering Sleep mode.

• Some device features or peripherals can continue

to operate. This includes items such as the input

change notification on the I/O ports, or peripherals

that use an external clock input.

• Any peripheral that requires the system clock

source for its operation is disabled.

The device wakes up from Sleep mode on any of these

events:

• Any interrupt source that is individually enabled

• Any form of device Reset

• A WDT time-out

On wake-up from Sleep mode, the processor restarts

with the same clock source that was active when Sleep

mode was entered.

EXAMPLE 10-1:

PWRSAV

INSTRUCTION SYNTAX

Note 1: This data sheet summarizes the features

the

dsPIC33FJ32GP302/304,

dsPIC33FJ64GPX02/X04,

and

dsPIC33FJ128GPX02/X04

families

devices. It is not intended to be a compre-

hensive reference source. To comple-

ment the information in this data sheet,

refer to “Section 9. Watchdog Timer

and Power-Saving Modes” (DS70196)

of the “dsPIC33F/PIC24H Family Refer-

ence Manual”, which is available from the

Microchip website (www.microchip.com).

2: Some registers

and

associated bits

described in this section may not be avail-

able on all devices. Refer to Section 4.0

“Memory Organization” in this data

sheet for device-specific register and bit

information.

Note:

SLEEP_MODE and IDLE_MODE are

constants

defined

the

assembler

include file for the selected device.

PWRSAV

#SLEEP_MODE

; Put the device into SLEEP mode

PWRSAV

#IDLE_MODE

; Put the device into IDLE mode

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