the expansion circuit of a 8-bits parallel port of PI port

Published:2011/8/11 4:01:00 Author:Ariel Wang | Keyword: expansion, 8-bits , parallel, port, PI | From:SeekIC

If there are toomany expansions and strobe signals take too many bits of parallel ports.For example,if you want to expand 8 parallel output ports.Then you need 8 signals.At this time,just these signals can take 8-bits parallel ports.Such huge resources wasting phenomena in singlechip system with limited I/O port linesare not tolerable.It adopts chip 74HC573( octal transparent type D flip-latch with three state output) to expand p1 port with 8-bits parallel port.Strobe signal adopts P3.3's pin of P3 port. The principle diagram is as seen as above.



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