DSPIC33FJ128MC802-ISP Datasheet, PDF (157/425 Pages) Microchip Technology – High-Performance, 16-bit Digital Signal Controllers

dsPIC33FJ32MC302/304, dsPIC33FJ64MCX02/X04 AND dsPIC33FJ128MCX02/X04
10.0 POWER-SAVING FEATURES
Note 1: This data sheet summarizes the features
of the dsPIC33FJ32MC302/304,
dsPIC33FJ64MCX02/X04
and
dsPIC33FJ128MCX02/X04 family of
devices. It is not intended to be a
comprehensive reference source. To
complement the information in this data
sheet, refer to “Section 9. Watchdog
Timer and Power Savings Modes”
(DS70196) of the “dsPIC33F/PIC24H
Family Reference Manual”, which is avail-
able 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.
The
dsPIC33FJ32MC302/304,
dsPIC33FJ64MCX02/X04
and
dsPIC33FJ128MCX02/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.
dsPIC33FJ32MC302/304, dsPIC33FJ64MCX02/X04
and dsPIC33FJ128MCX02/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
selectively tailor an application’s power consumption
while still maintaining critical application features, such
as timing-sensitive communications.
10.1 Clock Frequency and Clock
Switching
dsPIC33FJ32MC302/304, dsPIC33FJ64MCX02/X04
and dsPIC33FJ128MCX02/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
dsPIC33FJ32MC302/304, dsPIC33FJ64MCX02/X04
and dsPIC33FJ128MCX02/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.
Note:
SLEEP_MODE and IDLE_MODE are
constants defined in the assembler
include file for the selected device.
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 the
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
PWRSAV #SLEEP_MODE
PWRSAV #IDLE_MODE
; Put the device into SLEEP mode
; Put the device into IDLE mode
© 2009 Microchip Technology Inc.
Preliminary
DS70291D-page 157