In the world of embedded connected devices, inefficient power management could result in poor battery life, excess heat dissipation and unsatisfied customers.
Solution to above problem in the world of battery operated devices is "Efficient Power Management", which is undoubtedly required for all smart phones and tablet devices.Power management is a combined hardware and software mechanism to reduce the power consumption of a device in active and sleep mode.
The ultimate aim is to make resourceful utilization of power which could result in longer battery life and efficient usage of device resources in terms of power consumption.Before discovering ways to achieve efficient power management; let's have a look at typical battery operated embedded devices model.
Suspend and resume block implements the platform hooks and driver specific suspend and resume functionality. The platform hooks like prepare (), enter (), finish (), valid () are useful in making the device to enter into suspend and resume its operation state back to original. The platform hooks are like generic instructors to whole system; it instructs or commands the device to switch between suspend and resume states based on CPU state.
Usually the suspend event will be triggered on android device using power ON key and screen time out. The resume event will be triggered by using same Power ON key or any other hardware/software interrupts (Incoming call, Incoming message and alarms etc...). The CPU idle block will come in to picture when there is nothing left to run, in this mode CPU will execute power saving halt instructions, enter NAP mode and even disable the timers.
The CPU itself will supports different operating modes like WAIT, STOP, Standby and Deep sleep mode etc. The "WAIT" mode of the CPU will be triggered by "Idle process of operating system"; the "STOP" mode of the CPU will triggered by OS when system is waiting for operation. When there is a limited interaction with external events standby mode will be triggered. In similarly way the deep sleep mode will be triggered after surpassing the "STOP" mode.