5. Power-Down Modes
Rev.3.00 Jul. 19, 2007 page 107 of 532
REJ09B0397-0300
Bits 1 and 0—Subactive Mode Clock Select (SA1, SA0):
These bits select the CPU clock rate
(
φ
W
/2,
φ
W
/4, or
φ
W
/8) in subactive mode. SA1 and SA0 cannot be modified in subactive mode.
Bit 1: SA1
Bit 0: SA0
Description
0 0
φ
W
/8 (initial
value)
1
φ
W
/4
1
*
φ
W
/2
Legend:
*
Don't care
5.2 Sleep
Mode
5.2.1
Transition to Sleep Mode
The system goes from active mode to sleep mode when a SLEEP instruction is executed while the
SSBY and LSON bits in system control register 1 (SYSCR1) are cleared to 0. In sleep mode CPU
operation is halted but the on-chip peripheral functions other than PWM* are operational. The
CPU register contents are retained.
Note: * This is a function of the H8/3857 Group only, and is not provided in the H8/3854
Group.
5.2.2
Clearing Sleep Mode
Sleep mode is cleared by an interrupt (timer A, timer B, timer C*, timer F, IRQ
0
, IRQ
1
, IRQ
2
*,
IRQ
3
, IRQ
4
, WKP
0
to WKP
7
, SCI1*, SCI3, A/D converter) or by input at the
RES
pin.
Note: * The timer C, SCI1, and IRQ
2
interrupts are functions of the H8/3857 Group only, and
are not provided in the H8/3854 Group.
Clearing by Interrupt:
When an interrupt is requested, sleep mode is cleared and interrupt
exception handling starts. Operation resumes in active (high-speed) mode if MSON = 0 in
SYSCR2, or active (medium-speed) mode if MSON = 1. Sleep mode is not cleared if the I bit of
the condition code register (CCR) is set to 1 or the particular interrupt is disabled in the interrupt
enable register.
Clearing by
RES
Input:
When the
RES
pin goes low, the CPU goes into the reset state and sleep
mode is cleared.
Содержание F-ZTAT H8 Series
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