In recent years, various electronic apparatuses, each of which is equipped with a wireless communication system, have found widespread application. The wireless communication system is configured with a master wireless device and a terminal device that performs wireless communication with the master wireless device. The master wireless device and the terminal device are caused to be paired with each other and are set to possibly perform wireless communication. Normally, the terminal device operates on a built-in battery. In recent years, development of small-sized lightweight power generation devices has been in progress as well, and the number of proposals for terminal devices, each of which has a built-in power generation device as a power generator, has increased as well. The applicant has proposed PTL 1.
A terminal device that is disclosed in PTL 1 has a built-in power generator and causes a control circuit to operate only with power from the power generator. That is, a voltage in accordance with power that is obtained from the power generator is supplied, as a power source voltage, to a control circuit, and thus the terminal device is activated. The terminal device is configured to switch between a normal mode that is normally used and a registration mode that is used when paired with a master wireless device, according to a time interval at which the terminal device is repeatedly activated multiple times. The terminal device transmits, by radio, a normal mode signal through the control circuit in the case of the normal mode, and transmits, by radio, a pairing mode signal for paring in the case of the registration mode.
In order to determine that the terminal device is switched to the registration mode, a determination circuit is connected to the control circuit in the terminal device. The determination circuit is configured with a time constant circuit including a resistor and a capacitor in such a manner that the voltage which is obtained from an output port of the control circuit is lowered according to a time constant. The voltage of the determination circuit, which is lowered, is read in an input port of the control circuit. The control circuit previously has a first reference value (a high voltage) and a second reference value (a lower voltage), and compares the first reference value and the second reference value against a voltage value from the determination circuit, which is read in the input port. The control circuit determines that the time interval of the activation of the terminal device is a short time in a case where the voltage value from the determination circuit is higher than the first reference value. The control unit determines that the time interval is a long time in a case where the voltage value is lower than the second reference value.
The terminal device is repeatedly activated multiple times. In a case where a plurality of results of the determination that are obtained with this activation is consistent with a predetermined pattern, the terminal device proceeds from the normal mode to the registration mode.
As described above, the terminal device determines the time interval at which the activation is performed multiple times, based on the voltage value from the time constant circuit, and transmits either a first signal or a second signal by radio in accordance with a mode that corresponds to the plurality of results of the determination.