MCP23008 IO Expander - Demultiplexer

 

Dual HC573 buffer board on line testing - Stage 1, without deMUX.

http://www.blogger.com/blogger.g?blogID=1840459474737789074#editor/target=post;postID=1275978251996017803

Now I have connected the dual HC573 buffer board to the IO expander #2 and the deMUX.


1. IOx MCP23008 #1 8 wire cable (GP0 to GP7) to 8 bit input (B) of Dual HC573 buffer board

2.  DeMUX output 8 wire cable (Y0 to Y7) to 8bit demux select input of dual buffer board.

For now I have hard wired both buffer's LE to ground.  In other words, the DeMUX is not used for now.  Both buffers and always selected.

3. I connected the LCD1602 to the HC573's Q0 to Q5, and execute the old program that displays something on the LCD.

Results - both buffer works OK.

Next step is using the deMUX to replace the hardwired LE signals.

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