13. A method of controlling a terminal device, comprising:providing a terminal device including a control circuit which includes a first input unit, a second input unit, an output unit, a nonvolatile memory, a signal processing circuit, and a timer:
applying a second voltage as a power source voltage to the first input unit from a first time by performing an m-th operation of the terminal device;
causing the control circuit to start to operate by applying the power source voltage;
causing the control circuit to stop operating at a second time by causing the second voltage to fall below a lower limit voltage value;
inputting an output value of a voltage detector from the second input unit;
determining the m-th registration data according to a time measured by the timer after a third time at which the output value exceeds a first threshold which is predetermined; and
outputting either a first signal or a second signal as an output signal from the output unit according to first to (m?1)-th pieces of registration data or according to first to (m?1)-th pieces of registration data and m-th registration data which are stored in the nonvolatile memory.