Sensor controller, active pen, and communication method

An integrated circuit for use with an active pen that controls transmission of a downlink signal based on an uplink signal transmitted from a sensor controller, the integrated circuit comprising:

• a processor;
• and
• a memory storing instructions that, when executed by the processor, cause the integrated circuit to:
• transmit a downlink signal including first identification data via a pen tip electrode of the active pen after the active pen has been paired with the sensor controller, and in a case where an uplink signal including second identification data corresponding to the first identification data is received, control transmission of a next downlink signal via the pen tip electrode based on the second identification data,
• wherein each of the first identification data and the second identification data is contact state data indicating whether a pen tip of the active pen is in contact with a touch surface;
• and
• compare the second identification data included in the uplink signal with the first identification data included in the downlink signal and control transmission of the next downlink signal depending on a result of comparing the second identification data included in the uplink signal with the first identification data included in the downlink signal.