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22.4
Usage Notes
22.4.1
I/O Port State
In software standby mode, I/O port states are retained. Therefore, there is no reduction in current
consumption for the output current when a high-level signal is output.
22.4.2
Current Consumption during Oscillation Stabilization Standby Period
Current consumption increases during the oscillation stabilization standby period.
22.4.3
On-Chip Peripheral Module Interrupts
Relevant interrupt operations cannot be performed in module stop mode. Consequently, if module
stop mode is entered when an interrupt has been requested, it will not be possible to clear the CPU
interrupt source. Interrupts should therefore be disabled before entering module stop mode.
22.4.4
Writing to MSTPCR, EXMSTPCR
MSTPCR and EXMSTPCR should only be written to by the CPU.
22.4.5
Notes on Clock Division Mode
The following points should be noted in clock division mode.
• Select the clock division ratio specified by the SCK2 to SCK0 bits so that the frequency of φ is
within the operation guaranteed range of clock cycle time tcyc shown in the Electrical
Characteristics. In other words, the range of φ must be specified to 5 MHz (min.); outside of
this range (φ < 5 MHz) must be prevented.
• All the on-chip peripheral modules operate on φ. Therefore, note that the time processing of
modules such as a timer and SCI differs before and after changing the clock division ratio. In
addition, wait time for clearing software standby mode differs by changing the clock division
ratio.
• Note that the clock output of the φ pin will be changed by changing the clock division ratio.
Rev. 1.00, 09/03, page 633 of 704
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