Datasheet

Section 2 CPU
Rev. 2.00 Sep. 23, 2005 Page 36 of 444
REJ09B0068-0200
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. For the program halt
state, there are a sleep mode, standby mode, and sub-sleep 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
Subsleep mode
Power-down
modes
The CPU executes successive program
instructions at high speed,
synchronized by the system clock
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 Operating States
Reset state
Program halt state
Exception-handling state
Program execution state
Reset cleared
SLEEP instruction executed
Reset
occurs
Interrupt
source
Reset
occurs
Interrupt
source
Exception-
handling
complete
Reset occurs
Figure 2.12 State Transitions