A device for utilizing camera motion detection for a camera input interface includes a feature extractor, a feature tracker and a capture module. In some embodiments, a generally planar plate is pivotally coupled to a foot-receiving shell. A technique is described for detecting an overflow condition of running out of journal space and recovering the journal space. Characteristics are defined for the first plurality of curves. This serves to suppress noise at the start of operation and to keep the PLL locked, and as a result, the supply of the internal clock signal can be stabilized even at the time of mode switching.