Vehicle-mounted device and key switch identification method

摘要

VEHICLE-MOUNTED DEVICE AND KEY SWITCH IDENTIFICATION A voltage detector (22) has an input port (IN) connectable to a steering remote control (6) of a voltage dividing type adapted to output one of output voltages different from each other for each of key switches to be pressed by a user, and detects through the input port (IN) an output voltage output from the steering remote control (6). A pull-up 1o resistor (21 a) is connected in series between the input port (IN) and a power supply (Vdd) supplying a voltage to the steering remote control (6) and has a variable resistance. A controller (23) controls the pull-up resistor (21 a) to have sequentially changed resistances in a course of pressing the key switches. A processor (3) operates on sets of output voltages given respectively for the resistances in the course of pressing the key switches, is to select a resistance of the pull-up resistor.