hi all so i was wondering could i thoreticaly use 2 CD74HC4067 (one for x one for y) to form a swich matrix grid to get thoreticaly 256 switches with just 8 data lines (but i do have 10 spare data lines to work with in total) as i doing a projecet that requiers meany meany switches but i need to use smallest MCU i can (space restrictions) (i can have a fue ic spread out but not one large ic)
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What needs 256 switches ?
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Have you considered a 16 X 16 switch matrix (256 switches) ?
I think that is what @merlinuk11 is suggesting.
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Yes, I think it could be done. But you would need a 9th pin to read the switch.
that why i asking if i am able to use 2 CD74HC4067 to do this task
and this part will be a water leavle moniter useing reed switches and a magnet
spot on
that can be doable i do have a max of 10 data pins to work with
You could go one small step for mankind further and use just a few of those to run port expanders.
a7
You could do that with one analog input pin. Connect 254 resistors in series to form a voltage divider and have the reed switches connect one of the junctions to an analog input. No multiplexers needed.
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This part is confusing; please flesh your idea out a bit more.
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Will there ever be more than 1 switch pressed at a time ?
ye sorry misstyped there will edit to make clear and no there will onaly ever be one swich a time closed
ho thank you for the info
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This comes up now and then so I made a schematic of all 256 switches.
See the Attached PDF. -
I did cut and paste, I think everything is properly connected.
Root_1.pdf (87.7 KB)
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