Timing synchronization of active stylus and touch sensor

Abstract

In one embodiment, a stylus includes a controller, a delay line, a coefficient line and a computer-readable non-transitory storage medium. The controller is operable to receive a synchronization signal that is transmitted from a computing device and received by the stylus. The delay line is operable to store a first consecutive edges of the synchronization signal. The coefficient line includes a pre-determined coefficient vector. The computer-readable non-transitory storage medium embodies logic that is configured when executed to: determine a first correlation between the first consecutive edges of the synchronization signal and the pre-determined coefficient vector of the coefficient line; remove oldest signal period of edges of the first consecutive edges from the delay line; store next signal period of new consecutive edges of the synchronization signal to the delay line, the new consecutive edges composing a second consecutive edges of the synchronization signal; determine a second correlation between the second consecutive edges of the synchronization signal and the pro-determined coefficient vector; and synchronize one or more timings for communication between the stylus and the computing device based at least in part on the first and second correlations.