Microchip Technology DM163025-1 Fiche De Données
PIC18(L)F2X/45K50
DS30684A-page 60
2012 Microchip Technology Inc.
4.4
Idle Modes
The Idle modes allow the controller’s CPU to be
selectively shut down while the peripherals continue to
operate. Selecting a particular Idle mode allows users
to further manage power consumption.
If the IDLEN bit is set to a ‘1’ when a SLEEP instruction is
executed, the peripherals will be clocked from the clock
source selected by the SCS<1:0> bits; however, the CPU
will not be clocked. The clock source status bits are not
affected. Setting IDLEN and executing a SLEEP instruc-
tion provides a quick method of switching from a given
Run mode to its corresponding Idle mode.
If the WDT is selected, the INTRC source will continue
to operate. If the SOSC oscillator is enabled, it will also
continue to run.
selectively shut down while the peripherals continue to
operate. Selecting a particular Idle mode allows users
to further manage power consumption.
If the IDLEN bit is set to a ‘1’ when a SLEEP instruction is
executed, the peripherals will be clocked from the clock
source selected by the SCS<1:0> bits; however, the CPU
will not be clocked. The clock source status bits are not
affected. Setting IDLEN and executing a SLEEP instruc-
tion provides a quick method of switching from a given
Run mode to its corresponding Idle mode.
If the WDT is selected, the INTRC source will continue
to operate. If the SOSC oscillator is enabled, it will also
continue to run.
Since the CPU is not executing instructions, the only
exits from any of the Idle modes are by interrupt, WDT
time-out, or a Reset. When a wake event occurs, CPU
execution is delayed by an interval of T
exits from any of the Idle modes are by interrupt, WDT
time-out, or a Reset. When a wake event occurs, CPU
execution is delayed by an interval of T
CSD
while it
becomes ready to execute code. When the CPU
begins executing code, it resumes with the same clock
source for the current Idle mode. For example, when
waking from RC_IDLE mode, the internal oscillator
block will clock the CPU and peripherals (in other
words, RC_RUN mode). The IDLEN and SCS bits are
not affected by the wake-up.
While in any Idle mode or the Sleep mode, a WDT
time-out will result in a WDT wake-up to the Run mode
currently specified by the SCS<1:0> bits.
begins executing code, it resumes with the same clock
source for the current Idle mode. For example, when
waking from RC_IDLE mode, the internal oscillator
block will clock the CPU and peripherals (in other
words, RC_RUN mode). The IDLEN and SCS bits are
not affected by the wake-up.
While in any Idle mode or the Sleep mode, a WDT
time-out will result in a WDT wake-up to the Run mode
currently specified by the SCS<1:0> bits.
FIGURE 4-4:
TRANSITION TIMING FOR ENTRY TO SLEEP MODE
FIGURE 4-5:
TRANSITION TIMING FOR WAKE FROM SLEEP (HSPLL)
4.4.1
PRI_IDLE MODE
This mode is unique among the three low-power Idle
modes, in that it does not disable the primary device
clock. For timing sensitive applications, this allows for
the fastest resumption of device operation with its more
accurate primary clock source, since the clock source
does not have to “warm-up” or transition from another
oscillator.
PRI_IDLE mode is entered from PRI_RUN mode by
setting the IDLEN bit and executing a SLEEP instruc-
tion. If the device is in another Run mode, set IDLEN
first, then clear the SCS bits and execute SLEEP.
Although the CPU is disabled, the peripherals continue
modes, in that it does not disable the primary device
clock. For timing sensitive applications, this allows for
the fastest resumption of device operation with its more
accurate primary clock source, since the clock source
does not have to “warm-up” or transition from another
oscillator.
PRI_IDLE mode is entered from PRI_RUN mode by
setting the IDLEN bit and executing a SLEEP instruc-
tion. If the device is in another Run mode, set IDLEN
first, then clear the SCS bits and execute SLEEP.
Although the CPU is disabled, the peripherals continue
to be clocked from the primary clock source specified
by the FOSC<3:0> Configuration bits. The OSTS bit
remains set (see
by the FOSC<3:0> Configuration bits. The OSTS bit
remains set (see
When a wake event occurs, the CPU is clocked from the
primary clock source. A delay of interval T
primary clock source. A delay of interval T
CSD
is
required between the wake event and when code
execution starts. This is required to allow the CPU to
become ready to execute instructions. After the wake-
up, the OSTS bit remains set. The IDLEN and SCS bits
are not affected by the wake-up (see
execution starts. This is required to allow the CPU to
become ready to execute instructions. After the wake-
up, the OSTS bit remains set. The IDLEN and SCS bits
are not affected by the wake-up (see
).
Q4
Q3
Q2
OSC1
Peripheral
Sleep
Program
Q1
Q1
Counter
Clock
CPU
Clock
PC + 2
PC
Q3 Q4 Q1 Q2
OSC1
Peripheral
Program
PC
PLL Clock
Q3 Q4
Output
CPU Clock
Q1
Q2 Q3 Q4 Q1 Q2
Clock
Counter
PC + 6
PC + 4
Q1 Q2 Q3 Q4
Wake Event
Note 1:
T
OST
= 1024 T
OSC
; T
PLL
= 2 ms (approx). These intervals are not shown to scale.
T
OST(1)
T
PLL(1)
OSTS bit set
PC + 2