Input device using a rotary DIP switch

摘要

PPROBLEM TO BE SOLVED: To provide an input device using a rotary dip switch, capable of effectively utilizing the I/O port of a control IC 11 and reducing a mounting area on a substrate. PSOLUTION: In this input device, a key matrix circuit 31 connects row lines H1-H5 through a noise countermeasure circuit 32 to the input terminals R1-R5 of a control IC 33, executes pull-up to a power supply voltage VDD through a resistor R, and further connects the row lines H1-H4 to the terminals A, E, B and D of the rotary dip switch 34 through diodes D1-D4 in a forward direction. The control IC 33 supplies scanning signals outputted from open drain output terminals C1-C5 to the column lines V1-V4 of the key matrix circuit 31 and the common terminal C of the rotary dip switch 34, fetches in the input information of the input terminals R1-R5, and discriminates the operation contents of the key matrix circuit 31 and the setting contents of the rotary dip switch 34 by the timing of the scanning signals and the input information. PCOPYRIGHT: (C)2009,JPO&INPIT