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2.8
Processing States
2.8.1
Overview
The H8/300H CPU has five processing states: the program execution state, exception-handling
state, power-down state, reset state, and bus-released state. The power-down state includes sleep
mode, software standby mode, and hardware standby mode. Figure 2-11 classifies the processing
states. Figure 2-13 indicates the state transitions.
Processing states
48
Program execution state
The CPU executes program instructions in sequence
Exception-handling state
A transient state in which the CPU executes a hardware sequence
(saving PC and CCR, fetching a vector, etc.) in response to a reset,
interrupt, or other exception
Bus-released state
The external bus has been released in response to a bus request
signal from a bus master other than the CPU
Reset state
The CPU and all on-chip supporting modules are initialized and halted
Power-down state
The CPU is halted to conserve power
Figure 2-11 Processing States
Sleep mode
Software standby mode
Hardware standby mode
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