US Patent 11989377 Pen and sensor controller

A pen includes reception circuitry configured to receive an uplink signal generated according to a first protocol. The pen includes transmission circuitry configured to transmit a downlink signal on the basis of a reception timing of the uplink signal and a command included in the uplink signal. In a case where the reception circuitry, after receiving the uplink signal, in a period in which the next uplink signal is receivable, receives an uplink signal that is in a special state instead of receiving the next uplink signal normally, the transmission circuitry transmits, according to the first protocol, the downlink signal including either data according to the command or default data.