Datasheet

Section 2 CPU
Rev.4.00 Nov. 02, 2005 Page 34 of 304
REJ09B0143-0400
2.7 CPU States
There are four CPU states: the reset state, program execution state, program halt state, and
exception-handling state. The program execution state includes active mode. In the program halt
state there are a sleep mode, and standby mode. These states are shown in figure 2.11. Figure 2.12
shows the state transitions. For details on program execution state and program halt state, refer to
section 6, Power-Down Modes. For details on exception processing, refer to section 3, Exception
Handling.
CPU state Reset state
Program
execution state
Program halt state
Exception-
handling state
Active
(high speed) mode
Sleep mode
Power-down
modes
The CPU executes successive program
instructions at high speed,
synchronized by the system clock
The CPU executes
successive program
instructions at reduced
speed, synchronized
by the subclock
A state in which some
or all of the chip
functions are stopped
to conserve power
A transient state in which the CPU changes
the processing flow due to a reset or an interrupt
The CPU is initialized
Standby mode
Figure 2.11 CPU Operation States