Timing synchronization of active stylus and touch sensor

A stylus, which communicates data to a touch-controller, the stylus comprising:

• one or more electrodes included in a tip;
• and
• a computer-readable non-transitory storage medium embodying logic that is configured when executed to:
• receive, by the one or more electrodes and an analog front end, synchronization signals transmitted from a touch sensor coupled to the touch-sensor controller, and convert the synchronization signals into sequences of digital signals;
• feed the sequences of digital signals received in different periods into a memory;
• correlate each of the sequences of digital signals with a digital data defined by a pre-determined wide-band code to generate multiple correlations, wherein the wide-band code includes ones and zeros irregularly arranged;
• and
• synchronize, prior to the stylus starting communication of the data to the touch-sensor controller, one or more timings for the communication based at least in part on one or more of the multiple correlations.

A system including a stylus and a sensor,

• wherein, the sensor is configured to transmit synchronization signals, the synchronization signals utilize two-level symbols including periodic series of alternating logic highs and logic lows associated with particular voltage amplitudes, and the synchronization signals embed synchronization data including a series of repetitive square waves combined with noise, and
• wherein the stylus is configured to communicate data to a sensor controller coupled to the sensor, the stylus comprising:
• one or more electrodes included in a tip;
• and
• a computer-readable non-transitory storage medium embodying logic that is configured when executed to:
• receive, by the one or more electrodes and an analog front end, the synchronization signals transmitted from the sensor coupled to the sensor controller, and convert the synchronization signals into sequences of digital signals;
• feed the sequences of digital signals received in different periods into a memory;
• correlate each of the sequences of digital signals with a digital data defined by a pre-determined wide-band code to generate multiple correlations, wherein the wide-band code includes ones and zeros irregularly arranged;
• and
• synchronize, prior to the stylus starting communication of the data to the sensor controller, one or more timings for the communication based at least in part on one or more of the multiple correlations.

A controller integrated circuit configured to control a stylus, wherein the stylus communicates data to a touch-controller and the stylus includes a tip and one or more electrodes included in the tip, the controller integrated circuit comprising:

• (a) an analog front end configured to receive synchronization signals transmitted from a touch sensor coupled to the touch-sensor controller, and to convert the synchronization signals into sequences of digital signals;
• and
• (b) a correlator coupled to a memory, configured to:
• (i) feed a first sequence of digital signals received during a first signal period into the memory, and determine a first correlation by correlating the first sequence of digital signals with a pre-determined vector defined by a code, and
• (ii) feed a second sequence of digital signals received during a second signal period into the memory, and determine a second correlation by correlating the second sequence of digital signals with the pre-determined vector,
• wherein the controller integrated circuit is configured to synchronize, prior to the stylus starting communication of the data to the touch-sensor controller, one or more timings for the communication based at least in part on the first and the second correlations.