Patent ID: 8421498

Claim:
A semiconductor device having a bus connection circuit adapted to make communication with an external device through a bus line, the bus connection circuit including: an internal pull-up resistor and an internal pull-down resistor; an external pull-up determination unit for applying a pull-down voltage through the internal pull-down resistor to the bus line, and determining whether an external pull-up resistor external to the semiconductor device is connected on the bus line, the determination being made based on a voltage level of the bus line upon application of the pull-down voltage to the bus line; and an internal pull-up setting unit for stopping application of the pull-down voltage, and applying a pull-up voltage through the internal pull-up resistor to the bus line if the external pull-up determination unit determines that no external pull-up resistor is connected on the bus line, and for stopping application of the pull-down voltage if the external pull-up determination unit determines that the external pull-up resistor is connected on the bus line.