| 摘要 |
PURPOSE:To confirm easily a circuit to be controlled by using an output port for control as an input port for mounting detection. CONSTITUTION:A general-purpose input/output port is usually set in an output mode, and a central processor CC performs the blinking control of a light emitting diode LED put on a base board CKT of a circuit to be controlled. When the processor CC needs the decision for presence or absence of the board CKT, the corresponding PORT is changed to an input mode to read a signal output Z of an input gate G2. Then the connection or disconnection of the board CKT can be decided. If this decision is carried out while the diode LED is kept off, no effect is given to the blinking of the LED since the input level of a gate G3 is kept at 1 owing to a high impedance of an output gate G1. |
