PIC18F6390 Datasheet, PDF (49/412 Pages) Microchip Technology – 64/80-Pin Flash Microcontrollers with LCD Driver and nanoWatt Technology

PIC18F6390/6490/8390/8490
3.4.2 SEC_IDLE MODE
In SEC_IDLE mode, the CPU is disabled but the
peripherals continue to be clocked from the Timer1
oscillator. This mode is entered from SEC_RUN by set-
ting the IDLEN bit and executing a SLEEP instruction. If
the device is in another Run mode, set IDLEN first, then
set SCS1:SCS0 to ‘01’ and execute SLEEP. When the
clock source is switched to the Timer1 oscillator, the
primary oscillator is shut down, the OSTS bit is cleared
and the T1RUN bit is set.
When a wake event occurs, the peripherals continue to
be clocked from the Timer1 oscillator. After an interval
of TCSD following the wake event, the CPU begins
executing code being clocked by the Timer1 oscillator.
The IDLEN and SCS bits are not affected by the
wake-up; the Timer1 oscillator continues to run (see
Figure 3-8).
Note:
The Timer1 oscillator should already be
running prior to entering SEC_IDLE mode.
If the T1OSCEN bit is not set when the
SLEEP instruction is executed, the SLEEP
instruction will be ignored and entry to
SEC_IDLE mode will not occur. If the
Timer1 oscillator is enabled, but not yet
running, peripheral clocks will be delayed
until the oscillator has started. In such
situations, initial oscillator operation is far
from stable and unpredictable operation
may result.
3.4.3 RC_IDLE MODE
In RC_IDLE mode, the CPU is disabled but the periph-
erals continue to be clocked from the internal oscillator
block using the INTOSC multiplexer. This mode allows
for controllable power conservation during Idle periods.
From RC_RUN, this mode is entered by setting the
IDLEN bit and executing a SLEEP instruction. If the
device is in another Run mode, first set IDLEN, then set
the SCS1 bit and execute SLEEP. Although its value is
ignored, it is recommended that SCS0 also be cleared;
this is to maintain software compatibility with future
devices. The INTOSC multiplexer may be used to
select a higher clock frequency by modifying the IRCF
bits before executing the SLEEP instruction. When the
clock source is switched to the INTOSC multiplexer, the
primary oscillator is shut down and the OSTS bit is
cleared.
If the IRCF bits are set to any non-zero value, or the
INTSRC bit is set, the INTOSC output is enabled. The
IOFS bit becomes set after the INTOSC output
becomes stable after an interval of TIOBST
(parameter 39, Table 26-10). Clocks to the peripherals
continue while the INTOSC source stabilizes. If the
IRCF bits were previously at a non-zero value, or
INTSRC was set before the SLEEP instruction was
executed and the INTOSC source was already stable,
the IOFS bit will remain set. If the IRCF bits and
INTSRC are all clear, the INTOSC output will not be
enabled; the IOFS bit will remain clear and there will be
no indication of the current clock source.
When a wake event occurs, the peripherals continue to
be clocked from the INTOSC multiplexer. After a delay
of TCSD following the wake event, the CPU begins
executing code being clocked by the INTOSC multi-
plexer. The IDLEN and SCS bits are not affected by the
wake-up. The INTRC source will continue to run if
either the WDT or the Fail-Safe Clock Monitor is
enabled.
 2004 Microchip Technology Inc.
Preliminary
DS39629B-page 47