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Exception
handling state
Bus-released state
Software standby
mode
Reset state
*1
Sleep mode
Power down state
*3
Program execution state
End of bus request
Bus request
= High
= High,
= Low
Reset state
Hardware standby
mode
*2
E
nd of bus request
Bus request
Request for exception handling
Interrupt request
External interrupt request
SSBY = 0
SLEEP
instruction
SSBY = 1
SLEEP instruction
End of exception handling
Notes: 1. From any state except hardware standby mode, a transition to the reset state occurs whenever
goes low.
A transition can also be made to the reset state when the watchdog timer overflows.
2. In every state, when the STBY pin becomes low, the hardware standby mode is entered.
3. For details, refer to section 22, Power-Down Modes.
Figure 2.13 State Transitions
2.9 Usage
Note
2.9.1
Usage Notes on Bit-Wise Operation Instructions
The BSET, BCLR, BNOT, BST, and BIST instructions are used to read data in bytes, operate the
data in bit units, and write the result of the bit unit operation in bits again. Therefore, special care
is necessary to use these instructions for the registers and the ports that include write-only bit.
The BCLR instruction can be used to clear the flags in the internal I/O registers to 0. In this time,
if it is obvious that the flag has been set to 1 in the interrupt handler, there is no need to read the
flag beforehand.
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