Aggressive use of Deep Sleep mode in low power embedded systems

Since idle-state is the dominant state for embedded systems, disabling unused devices in idle-states can lead to significant power reduction. Among the various sleep modes provided by application processors, Deep Sleep mode offers maximum power savings. Since Deep Sleep mode requires to stop I/O devices and clocks, it is usually used in suspend-state. However, with the emergence of non-volatile or low power compute state retainable devices, we can now explore exploiting Deep Sleep mode in non-suspend states. We propose a new scheme to aggressively use Deep Sleep mode under normal operations. An experimental result of 48-80% power reduction on our prototype board indicates possibilities for near-future mobile platform running solely on photovoltaic-power.