摘要 |
A device includes a main power source for supplying power, and a memory for storing an augmented time which is greater than a current time and is updated periodically using a first clock. An auxiliary power source supplies power to a second clock for providing the current time when the main power source is incapable of providing power. A controller powered by the auxiliary power source is configured to set a start time when main power source is incapable of providing power. The auxiliary power source does not supply power to the second clock. |