There is provided an input device that needs not to change processing of means (a key processor or a key processing microcomputer as a software module) for performing processing based on an on or off state of a key switch in a matrix system and an A/D system. A key-in microcomputer detects the on or off states of plural key switches K based on voltages at A/D input terminals. The key-in microcomputer converts the detected on or off states of the plural key switches K into a bit array. A key processing microcomputer performs the processing based on the bit array converted by the key-in microcomputer.
1. An input device comprising: a plurality of key switches in each of which one end is connected to a terminal while the other end is grounded;
a first resistor in which one end is connected between the terminal and the key switch while the other end is connected to a power supply, the key switch beings connected to the terminal while located closest to the terminal in the plurality of key switches;
a plurality of second resistors each of which is connected between the two key switches adjacent to each other in the plurality of key switches;
a key-in unit that detects an on or off states of each of the plurality of key switches based on voltage at the terminal, and converts the detected on or off state of each of the plurality of key switches into a bit array by setting the detected on or off state of each of the plurality of key switches to an element 0 or 1 respectively; and
a key processor that performs processing based on the bit array converted by the key-in unit.
2. The input device according to claim 1 , wherein the plurality of the key switches are connected to each of the plurality of the terminals, and
the key-in unit converts the one or off states of the plurality of key switches connected to the one terminal into one bit array.
3. The input device according to claim 1 , wherein:
in the case that the voltage at the terminal changes from a power supply voltage to a threshold voltage associated with a particular one of the plurality of key switches being put into an on state, the key-in unit detects that the particular key switch is put into the on state, sets an element of the bit array corresponding to the particular key switch to 1, and with respect to the remaining plurality of key switches connected to the terminal, sets a corresponding element of the bit array for the remaining key switches which are located closer to the terminal relative to the particular key switch to 0, and sets a corresponding element of the bit array for the remaining key switches which are located farther away from the terminal relative to the particular key switch to their previously set value, and
in the case that the voltage at the terminal is equal to the power supply voltage, the key-in unit detects the off states of the plurality of key switches, and sets the corresponding elements of the bit array for all the plurality of key switches to 0.