User's Manual

CHAPTER THREE - PL3000 BASICS

POWER MANAGEMENT

In the PL3000 system, a so called power manager (PM) controls on power-

related things. One of the tasks of the PM is to save battery energy by reducing

power consumption. The rationale behind reducing the power usage is based on

the inactivity of a user or the system. For example, by default the PM turns off the

backlight of the screen, if the devise remains idle without any user input either key

press or stylus tapping on the screen for the specified period of time. On the

contrary, if a user or a user application action occurs it is the PM’s task to activate

the system. For instance, if the screen is turned off, the PM directs the system to

turning on the screen with the adjusted, maximum backlight brightness when the

user presses some key or taps the screen.

Power States

The PL3000 has two main power states: it is either switched on or switched

off. When the device is switched on, it can be on AC power, or it can be running on

battery. However, from the user’s point of view there are four distinctive system

power states, aka power levels, on the device: On, UserIdle, SystemIdle, and

Suspended.

Note! In this manual both ‘Suspended’ and ‘Sleep’ is used to refer to the

‘OFF’ state of the device, that is, to refer to the situation when the device

is switched off.

By default, if your PL3000 remains idle for a while it reaches the ‘Suspended’

via the UserIdle and SystemIdle states. For this transition from the ‘On’ state to the

‘Suspend’ state the PM uses three inactivity timers. If all the three timers expire the

PM suspends the PL3000. To put it another way, using the power button is not the

only way to switch off the device. By default the PM has always tendency to power

down the device to save energy when it is running on battery.

Be aware that you can power down your PL3000 through the power button in

whatever power state your device is, whether it is either in the ‘On’ or in the

intermediate power-saving states. In addition, if the battery cover is removed the

device powers off.

When PL3000 is switched off, it is said that it is

suspended. For the simple reason that the device

cannot be turned off completely but the critical parts of

the system’s electronics remain powered after powering down the device.

The PM suspends the device if the SystemIdle state is reached, provided that

a suspend timer expires. The suspend timer has a settings value of ‘Never’ (a

‘Suspend Timeout’ value), if set, the PM does not suspend the device.

Suspended