[sdiy] DOTCOM Analog Sequencer.. next project startup..

Ullrich Peter Peter.Ullrich at kapsch.net
Sat Jul 25 23:33:45 CEST 2020


One elegant method of reading multiple encoders with only a few lines is shown in this circuit:
This is onlx for the encoder part - not the push button part of the encoder.
I would make a standard keyboard matrix for the push button if there are lets say 32 encoders or so.
If you don't want to make the encoding in software on your own you could also use a keyboard encoder like the 74C922 or 74C923 if you can find some - as they are already obsolete. These can handle 16 or 20 push buttons.

Use an 74HC154 (http://www.om3bc.com/datasheets/74HC154.PDF ) if you need 16 encoders.
Or you can still use the 74HC138 and use the 3 chip select inputs for cascading.
Also the 74HC154 has chip select inputs, so cascading is also possible here.

For the decoupling diodes I normally use BAT42 or similar schottky diodes.
The pullups can be 10k for example.



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