Patent ID: 8334711

Claim:
A control circuit comprising: an input-output unit that is connected to a signal line, which is connected to an external apparatus, and which is connected to a resistor that is one of a pull-up resistor and a pull-down resistor; a switching unit that switches a mode of the input-output unit to one of an input mode and an output mode, wherein the output mode includes an on-voltage output mode and an off-voltage output mode; an acquisition unit that acquires information regarding whether the resistor connected to the signal line is the pull-up resistor or the pull-down resistor, when the input-output unit is in the input mode; and a control unit that controls the input-output unit to switch to one of the on-voltage output mode and the off-voltage output mode based on the acquisition information acquired by the acquisition unit, when the input-output unit is in the output mode.