An ultra low power apparatus and method to wake up a main processor

An apparatus and a method for waking up a main processor (MP) in a low power or ultra-low power device comprise a main processor and a sub-processor. The sub-processor consumes less power than the main processor for monitoring surrounding conditions, and is capable of being integrated with the main processor. The main processor and the sub-processor can be in a sleep mode while an interrupt sensor detects a change in the surrounding conditions. The interrupt sensor senses the change in the surrounding conditions, and wakes up the sub-processor by using an interrupt signal, when sensed sensing data is changed to a predetermined condition. Then, the sub-processor compares a prestored value with data received from the interrupt sensor, or determines by using values from other sensors whether the condition of the sensing data of the interrupt sensor indicates that the main processor is to be woken up, and wakes up the main processor based on a determined result. [Reference numerals] (110) Main processor (high power); (120) Sub-processor (low lower); (130) Interrupt (ultra-low power); (140) Polling sensor (ultra-low power)