| 摘要 |
PURPOSE:To prevent malfunction of an external device in a reset or initialization state of an input/output control circuit, by providing a control circuit between the input/output control circuit and the external device to perform active level control. CONSTITUTION:When the active level of a connected external device 30 is kept at a high level and an input/output control circuit 21 is reset or initialized, an output terminal 21out of the circuit 21 is set at a high impedance. Here a control circuit 22 cuts off the terminal 21out from the device 30 by a command given from a detection circuit 23 and sets the input level of an input terminal 30in of the device 30 at a low level. Under such conditions, the circuit 22 connects the terminal 30in and the terminal 21out by a command of the circuit 23 at a time point when the reset or initialization state of the circuit 21 is released and the terminal 21out is controllable. |
