Microchip Technology MA330012 데이터 시트
©
2007 Microchip Technology Inc.
Preliminary
DS70165E-page 157
dsPIC33F
9.0
POWER-SAVING FEATURES
The dsPIC33F 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 cir-
cuits being clocked constitutes lower consumed power.
dsPIC33F devices can manage power consumption in
four different ways:
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 cir-
cuits being clocked constitutes lower consumed power.
dsPIC33F devices can manage power consumption in
four different 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.
tively tailor an application’s power consumption while
still maintaining critical application features, such as
timing-sensitive communications.
9.1
Clock Frequency and Clock
Switching
Switching
dsPIC33F devices allow a wide range of clock frequen-
cies 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 8.0 “Oscillator
Configuration”.
cies 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 8.0 “Oscillator
Configuration”.
9.2
Instruction-Based Power-Saving
Modes
Modes
dsPIC33F devices have two special power-saving
modes that are entered through the execution of a
special
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 assembly syntax of
the
the CPU and code execution, but allows peripheral
modules to continue operation. The assembly syntax of
the
PWRSAV
instruction is shown in Example 9-1.
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”.
enabled interrupt, WDT time-out or a device Reset. When
the device exits these modes, it is said to “wake-up”.
9.2.1
SLEEP MODE
Sleep mode has these features:
• 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.
current.
• The Fail-Safe Clock Monitor does not operate
during Sleep mode since the system clock source
is disabled.
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 may continue
to operate in Sleep mode. 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 in Sleep mode.
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 in Sleep mode.
The device will wake-up from Sleep mode on any of the
these events:
these events:
• Any interrupt source that is individually enabled.
• Any form of device Reset.
• A WDT time-out.
On wake-up from Sleep, the processor restarts with the
same clock source that was active when Sleep mode
was entered.
same clock source that was active when Sleep mode
was entered.
EXAMPLE 9-1:
PWRSAV
INSTRUCTION SYNTAX
Note:
This data sheet summarizes the features
of this group of dsPIC33F devices. It is not
intended to be a comprehensive reference
source. To complement the information in
this data sheet, refer to the “dsPIC30F
Family Reference Manual” (DS70046).
of this group of dsPIC33F devices. It is not
intended to be a comprehensive reference
source. To complement the information in
this data sheet, refer to the “dsPIC30F
Family Reference Manual” (DS70046).
Note:
SLEEP_MODE and IDLE_MODE are
constants defined in the assembler
include file for the selected device.
constants defined in 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