Stylus hover and position communication protocol

A method for controlling an active stylus, the method comprising:

• receiving a synchronization waveform from the touch-sensitive device via capacitively coupling between a stylus electrode of the active stylus and one or more electrodes of a capacitance-based touch sensor of a touch-sensitive device;
• responsive to receiving the synchronization waveform, transmitting, via the stylus electrode, a first waveform during one or more sub-frames of a first set of sub-frames of a communication frame;
• if the active stylus is hovering, transmitting, via the stylus electrode, the first waveform during one or more sub-frames of a second set of sub-frames of the communication frame;
• and
• if the active stylus is not hovering, transmitting, via the stylus electrode, one or more additional waveforms during one or more sub-frames of the second set.

An active stylus, comprising:

• a stylus electrode configured to capacitively couple with one or more electrodes of a capacitance-based touch sensor of a touch-sensitive device;
• receive circuitry operatively coupled to the stylus electrode and configured to receive a synchronization waveform from the touch-sensitive device;
• and
• transmit circuitry operatively coupled to the stylus electrode and configured to, upon receiving the synchronization waveform, transmit stylus information to the touch-sensitive device according to a communication frame including a first set of sub-frames and a second set of sub-frames, where the transmit circuitry is configured to 1) transmit a first waveform during one or more sub-frames of the first set, 2) if the active stylus is hovering, transmit the first waveform during one or more sub-frames of the second set, and 3) if the active stylus is not hovering, transmit one or more additional waveforms during one or more sub-frames of the second set, where the active stylus is configured to operate in a sleep mode in which the active stylus does not transmit waveforms via the stylus electrode prior to receiving the synchronization waveform.