Stylus and controller

[Problem] To solve various problems that need to be solved to enable a stylus to be used on a non-in-cell type or in-cell type electronic device. [Solution] The stylus 2 according to the present invention is configured to be able to transmit stylus pressure data P to an electronic device, and comprises: a stylus electrode 20 which forms a coupling capacitance with a sensor electrode of the electronic device; and a signal processing circuit 21 which detects an uplink signal US using the stylus electrode 20, extracts a command from the detected uplink signal US, determines, on the basis of the extracted command, whether to operate in a first mode, in which data is transmitted using M first periods (where M ≥ 1), or in a second mode, in which data is transmitted using N second periods (where N > M), and transmits data repeatedly in accordance with the determined mode.