An active stylus includes at least one electrode, and an integrated circuit coupled to the at least one electrode. The integrated circuit is configured to: operate in a first mode to unilaterally transmit signals to a sensor controller from one of the at least one electrode; attempt to detect an uplink signal from the sensor controller, using one of the at least one electrode, in a time period T1 during which the unilateral transmission of signals to the sensor controller is suspended; in response to not detecting the uplink signal, repeat operating in the first mode to unilaterally transmit signals to the sensor controller; and in response to detecting the uplink signal, stop operating in the first mode and transition to a second mode in which to transmit a downlink signal to the sensor controller, wherein the downlink signal is responsive to the uplink signal transmitted from the sensor controller.