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2.2.3 Power OFF Process
Overview
Turns off the system power. However, the power to all the devices is not turned off and some can be
used for storing the information required for the next resume operation. This process is called the
suspend process and the state of the system while off is called the suspend state.
The suspend process can be divided into two categories: one is the normal suspend process which is
the usual off method and the other is the critical suspend process to execute the emergency escape
process for protecting the system from drops or bumps. Either of these suspend processes will be
selected depending on the OFF factor, as described later.
Normal Suspend Process
If the Power switch is held down for more than one second while system is on, the system power
will be turned off. The process that takes place at this time is the normal suspend process. Before
this suspend process is executed, the application currently running is informed of the suspend
request (OFF factor) by the system. Then the system stores the information required for resumption
and turns off the power.
Hereinafter the suspend process (or OFF process) refers to the normal suspend process.
For information about the method used by each application to detect the occurrence of an OFF factor
(suspend event), refer to Appendix C Acquisition of Suspend/Resume Event and Power Status.
Critical Suspend
This is a suspend process that takes place in an emergency. Since this critical suspend process should
achieve its escape process with very little power in the system, only essential information can be
retained.
The system will not inform the application currently running of the fact that it is critically
suspended. However, the application will be informed of the fact that it was critically suspended at
resumption.
For information about the method used by each application to receive this information, refer to
Appendix C Acquisition of Suspend/Resume Event and Power Status.