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CHAPTER 23 STANDBY FUNCTION
23.2.2 STOP mode
(1) STOP mode set and operating status
The STOP mode is set by executing the STOP instruction. It can be set only with the main system clock.
Cautions 1. When the STOP mode is set, the X2 pin is internally connected to V
DD1
via a pull-up resistor
to minimize the leakage current at the crystal oscillator. Thus, do not use the STOP mode
in a system where an external clock is used for the main system clock.
2. Because the interrupt request signal is used to clear the standby mode, if there is an
interrupt source with the interrupt request flag set and the interrupt mask flag reset, the
standby mode is immediately cleared if set. Thus, the STOP mode is reset to the HALT
mode immediately after execution of the STOP instruction. After the wait set using the
oscillation stabilization time select register (OSTS), the operating mode is set.
The operating status in the STOP mode is described below.
Table 23-3. STOP Mode Operating Status
Setting of STOP Mode
With Subsystem Clock
Without Subsystem Clock
Item
Clock generator
Only main system clock stops oscillation
CPU
Operation stops
Port (output latch)
Status before STOP mode setting is held
16-bit timer/event counter
Operable when watch timer output is
selected as count clock (f
XT
is selected as
count clock of watch timer)
Operation stops
8-bit timer/event counter
Operable when TI1 and TI2 are selected for the count clock
Watch timer
Operable when f
XT
is selected for the
count clock
Operation stops
Watchdog timer
Operation stops
A/D converter
D/A converter
Operable
Real-time output port
Operable when external trigger is used or TI1 and TI2 are selected for the 8-bit
timer/event counter count clock
Serial interface
Other than
automatic
transmit/receive
function and
UART
Operable when externally supplied clock is specified as the serial clock
Automatic
transmit/receive
function and
UART
Operation stops
External interrupt
request
INTP0
Not operable
INTP1 to INTP5
Operable
Bus line for
external
expansion
AD0 to AD7
High impedance
A0 to A15
Status before STOP mode setting is held
ASTB
Low level
WR, RD
High level
WAIT
High impedance