| 摘要 |
PURPOSE:To decrease the number of terminals at the microcomputer side for extension of an output port by providing a smoothing circuit which smooths the output received from a strobe signal output terminal and connecting the output side of the smoothing circuit to the enable signal input terminal of an external IC. CONSTITUTION:A microcomputer 9 outputs the data D of a single unit in a cycle of 1msec, for example, and applies the instant rise and fall to a strobe signal output terminal STOUT at each end of the output of the data D. Thus the microcomputer 9 changes intermittently a strobe signal input terminal STIN of an external IC 2 into a pulse form and outputs in parallel the data equivalent to 8 bits from the IC 2 by the output of the STOUT. The output received through the STOUT of the microcomputer 9 is smoothed by a smoothing circuit 11. Thus an enable input terminal EIN of the IC 2 is set in its hitherto level. Therefore, an enable state is never set after the first enable change nor the data output of the IC is never inhibited. |
