Methods for maintaining accurate timing information on portable electronic devices

Abstract

Methods for operating portable electronic devices to maintain accurate timing information are provided. In one suitable arrangement, an electronic device may have a real-time clock and a mach-time clock that can be used separately to track the Coordinated Universal Time (UTC). The offset of the real-time clock and the mach-time clock from UTC can be monitored to determine if there is any oscillator frequency drift, which can be characterized using a linear model. Any variation in drift caused by environment factors such as temperature may also be characterized. In another suitable arrangement, a primary electronic device that is capable of maintaining accurate timing information may transfer that information to a secondary user device. Timing information may be transferred using mach-time values and may then be converted to real-time clock values to ensure that the secondary user device can estimate time accurately even when the device goes to sleep.