The input and output interface in the present invention can includes following components. A first circuit and a second circuit are placed. Means for switching a coupling between the two circuits is used. Grounding means is employed for setting the first terminal to a ground connection. Triggering means is used for triggering the grounding means and the switching means. The method for interfacing input and output between a first circuit and a second circuit includes the steps as follows. At first, an output disable signal of the first circuit is detected. Then a first terminal is isolated from a second terminal. The first terminal is an input and output terminal of the first circuit and the second terminal is an input and output terminal of the second circuit. Next, the first terminal is grounded. The first terminal is then floated. Finally, the first terminal and the second terminal is coupled for the first circuit to receive an output signal from the second circuit.