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CHAPTER 20 STANDBY FUNCTION
20.2.2 STOP mode
(1) STOP mode setting and operating status
The STOP mode is set by executing the STOP instruction.
Cautions 1. When the STOP mode is set, the X2 pin is internally connected to V
DD
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 20-3. STOP Mode Operating Status
STOP Mode Setting
During STOP Instruction Execution Using Main System Clock
Item
Clock generator
Only main system clock oscillation is stopped.
CPU
Operation stops.
Port (Output latch)
Status before STOP mode setting is held.
16-bit timer
Operation stops.
8-bit timer
Operable only when TIO2 and TIO3 are selected as count clock.
Watch timer
Operation stops.
Watchdog timer
Operation stops.
A/D converter
Operation stops.
Serial interface
Other than UART
Operable only when externally supplied input clock is specified as the serial clock.
UART
Operation stops.
LCD controller/driver
Operation stops.
External interrupt
Operable
Sound generator
Operation stops.
Meter controller/driver
Operation stops.
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