Pulse Signal Outputting Apparatus

摘要

Radiated noises of an output pulse signal are reduced. A pulse signal outputting apparatus outputs a pulse signal generated by a modulating means outside, the modulating means includes a calculation circuit that has a pull-up resistor which is connected to power supply inside, 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, 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, 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 the general-purpose input/output terminal is switched to the output terminal by the input/output selecting means after a certain period of time has passed.

主权项

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 outside,
wherein the modulating means includes:
a calculation circuit that has a pull-up resistor which is connected to a power supply inside;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; anda 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.