Pulse signal outputting apparatus

1. A pulse signal outputting apparatus which includes physical amount detecting means for detecting a physical amount, and modulating means for performing pulse modulation on output information obtained from the physical amount detecting means, and which outputs a pulse signal generated by the modulating means,

wherein the modulating means includes:

a calculation circuit that has a pull-up resistor which is connected to a power supply;

a general-purpose input/output terminal that is connected to the calculation circuit;

input/output selecting means for selecting whether the general-purpose input/output terminal is used as an input terminal or an output terminal;

pull-up resistor connecting means for connecting or disconnecting the pull-up resistor and the general-purpose input/output terminal; and

a pull-up resistor connection control circuit that performs control so that the pull-up resistor connecting means is operated when the general-purpose input/output terminal is selected as the input terminal,

wherein the general-purpose input/output terminal is selected as the input terminal by the input/output selecting means when a transition of an output signal level of the pulse signal starts,

wherein the pull-up resistor and the general-purpose input/output terminal are connected by the pull-up resistor connecting means when the general-purpose input/output terminal is selected as the input terminal, and

wherein the general-purpose input/output terminal is switched to the output terminal by the input/output selecting means after a certain period of time is passed.

2. The pulse signal outputting apparatus according to claim 1 , comprising:

a transistor connected to the modulating means,

wherein the transistor is driven in an active region when the pull-up resistor is connected to the general-purpose input/output terminal.

3. The pulse signal outputting apparatus according to claim 1 , comprising:

a transistor connected to the modulating means,

wherein a potential at a base or a gate of the transistor is not continuous and is controlled to be two or more values of constant voltage widths.

4. The pulse signal outputting apparatus according to claim 1 , wherein connection or disconnection of the pull-up resistor is performed a plurality of times.

5. The pulse signal outputting apparatus according to claim 1 , wherein the pull-up resistor uses a resistance component of a semiconductor junction.

6. The pulse signal outputting apparatus according to claim 1 , wherein a receiving side of the pulse signal output by the pulse signal outputting apparatus uses a duty ratio, a leading edge, or a trailing edge of the pulse signal.

7. The pulse signal outputting apparatus according to claim 1 , wherein at least one of existence/non-existence, the number of times, and an operation period of time of a connection and disconnection operation, and the pull-up resistance value of the pull-up resistor is variable after an electric current is applied to the pulse signal outputting apparatus.

8. The pulse signal outputting apparatus according to claim 1 , wherein connection and disconnection of the pull-up resistor and an operation of selecting the general-purpose input/output terminal are performed even at a leading edge of the pulse signal.