| 摘要 |
<p>PROBLEM TO BE SOLVED: To surely identify a low signal from a voltage input to a microcomputer by setting a threshold to a high value by using an A/D conversion port, even when floating of a potential of a switch occurs due to an adverse effect or the like of wirings so that an input voltage of the microcomputer becomes high. SOLUTION: Switches 11 and 12 are connected to the A/D conversion port 17a via reverse diodes 13 and 14 and forward diodes 15 and 16. ON/OFF switchable pull-up control boards 18 and 19 and transistors 20 and 21 for applying a voltage of a lower potential than that of a power source 23 to the diodes 15 and 16 when the boards 18 and 19 are ON are provided between the diodes 13, 14 and the diodes 15, 16. An input circuit has a resistor R3 or the like connected at one end between the diodes 15, 16 and the port 17a and grounded at another end to a ground G2.</p> |
