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548
CHAPTER 25 STAND-BY FUNCTION
(2) IDLE mode
(a) Setting the IDLE mode and the operating states
When the low power consumption mode is set in the IDLE mode, set 47H in STBC.
Table 25-10 shows the operating states in the IDLE mode.
Table 25-10. Operating States in IDLE Mode
Item
Operating State
Clock generation circuit
The main system clock stops oscillating. The oscillation circuit of the subsystem clock
continues operating. The clock supplied to the CPU and the peripherals stops.
CPU
Operation disabled
Port (output latch)
Saves the state before setting the IDLE mode
16-bit timer/counter
Operational when the watch timer output is selected as the count clock
(Select f
XT
as the count clock of the watch timer.)
8-bit timer/counters 1, 2
Operational when TI1 and TI2 are selected as the count clocks
8-bit timer/counters 5, 6
Operational when TI5 and TI6 are selected as the count clocks
8-bit timer/counters 7, 8
Operational when TI7 and TI8 are selected as the count clocks
Watch timer
Operational only when f
XT
is selected as the count clock
Watchdog timer
Operation disabled
A/D converter
Operation disabled
D/A converter
Operation enabled
Real-time output port
Operational when an external trigger is used or TI1 and TI2 are selected as the count
clocks of the 8-bit timer/counters 1 and 2
Serial interface
I
2
C bus mode
Operational only when an external input clock is selected as the serial clock
I
2
C bus mode
External interrupt
External interrupt
INTP0 - INTP6
Operation enabled
Key return interrupt
P80 - P87
Operation enabled
Bus lines during
AD0 - AD7
High impedance
external expansion A0 - A19
Holds the state before the IDLE mode is set
ASTB
Low level
WR, RD
High level
WAIT
High impedance
Caution In the IDLE mode, only external interrupts (INTP0 to INTP6), watch timer interrupt (INTWT), and
key return interrupts (P80 to P87) can release the IDLE mode and be acknowledged as interrupt
requests. All other interrupt requests are pended, and acknowledged after the IDLE mode has
been released through NMI input, INTP0 to INTP6 input, INTWT, or key return interrupt.