h8s-2649 Renesas Electronics Corporation., h8s-2649 Datasheet - Page 87

• Manufacturer Part Number: h8s-2649
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2600 Series
• Manufacturer: Renesas Electronics Corporation.

2.8
The H8S/2600 CPU has five main processing states: the reset state, exception handling state,
program execution state, bus-released state, and power-down state. Figure 2.13 indicates the state
transitions.
• Reset State
• Exception-Handling State
• Program Execution State
• Bus-Released State
• Program stop state
In this state, the CPU and all on-chip peripheral modules are initialized and not operating.
When the RES input goes low, all current processing stops and the CPU enters the reset state.
All interrupts are masked in the reset state. Reset exception handling starts when the RES
signal changes from low to high. For details, refer to section 4, Exception Handling.
The reset state can also be entered by a watchdog timer overflow.
The exception-handling state is a transient state that occurs when the CPU alters the normal
processing flow due to an exception source, such as a reset, trace, interrupt, or trap instruction.
The CPU fetches a start address (vector) from the exception vector table and branches to that
address. For further details, refer to section 4, Exception Handling.
In this state, the CPU executes program instructions in sequence.
The bus has been released in response to a bus request from a bus master other than the CPU.
While the bus is released, the CPU halts operations.
This is a power-down state in which the CPU stops operating. The program stop state occurs
when a SLEEP instruction is executed or the CPU enters hardware standby mode. For further
details, refer to section 21, Power-Down Modes.
Processing States
Rev. 2.00 Dec. 05, 2005 Page 49 of 724
REJ09B0200-0200
Section 2 CPU