| 摘要 |
<p>PURPOSE:To switch an input and an output in a short time and easily by providing a means for inputting an input/output switching signal of an input/output port from the outside. CONSTITUTION:In the case of using an input/output port as an input port, an output use CMOS transistor is turned OFF so that input data can be read in by inputting an 'L' level to an input terminal 3 of an input/output switching signal, and setting an output signal POUT and an input signal PIN to 'L' and 'H', respectively. On the other hand, in the case of the input/output port as an output port, an output of the output use CMOS transistor can be varied by the contents of an output use latch 2 by inputting an 'H' level to the input terminal 3 of the input/output switching signal, and setting the output signal POUT and the input signal PIN to 'H' and 'L', respectively. In such a way, an input and an output of the input/output port is switched directly from the outside. Accordingly, the input and the output of the input/output port can be switched in a short time and easily.</p> |
