PIC18F26K80-I Datasheet, PDF (71/622 Pages) Microchip Technology – 28/40/44/64-Pin, Enhanced Flash Microcontrollers with ECAN™ and nanoWatt XLP Technology

PIC18F66K80 FAMILY
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 SCSx 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 Figure 4-7).
When a wake event occurs, the CPU is clocked from the
primary clock source. A delay of interval, TCSD
(Parameter 39, Table 31-11), is required between the
wake event and the start of code execution. 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 SCSx bits are not affected by the
wake-up (see Figure 4-8).
4.4.2 SEC_IDLE MODE
In SEC_IDLE mode, the CPU is disabled but the
peripherals continue to be clocked from the SOSC
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 the IDLEN bit
first, then set the SCS<1:0> bits to ‘01’ and execute
SLEEP. When the clock source is switched to the SOSC
oscillator, the primary oscillator is shut down, the OSTS
bit is cleared and the SOSCRUN bit is set.
When a wake event occurs, the peripherals continue to
be clocked from the SOSC oscillator. After an interval
of TCSD following the wake event, the CPU begins
executing code that is being clocked by the SOSC
oscillator. The IDLEN and SCSx bits are not affected by
the wake-up and the SOSC oscillator continues to run
(see Figure 4-8).
FIGURE 4-7:
TRANSITION TIMING FOR ENTRY TO IDLE MODE
Q1
Q2
Q3
Q4
Q1
OSC1
CPU Clock
Peripheral
Clock
Program
Counter
PC
PC + 2
FIGURE 4-8:
TRANSITION TIMING FOR WAKE FROM IDLE TO RUN MODE
Q1
Q2
Q3
Q4
OSC1
CPU Clock
TCSD
Peripheral
Clock
Program
Counter
PC
Wake Event
 2010-2012 Microchip Technology Inc.
DS39977F-page 71