I’m trying to combine this use of the shift register. With the ioAbstaction library.

But I’m not sure how to read the buttons.

The help in the library seems to suggest more pins for writing than the tutorial for the buttons.

The end goal is to have three LEDs and the buttons connected through the 74HC595 shift register using a minimal number of Ardunio pins.

  • Downvoter. Why? Is there something constructive you add? – Scott McKenzie May 26 at 8:40

The 74HC595 is a SerialToParallel shift register, mainly to have multiple outputs (SIPO).

You can abuse it to read multiple buttons by multiplexing:

Have one Arduino input pin and several output pins on the shift register to select the current button. This is what the instructables.com is showing.

No idea how that ioAbstraction library might help more than the Arduino-builtin shiftOut() function...

| improve this answer | |
  • The IoAbstraction library is to enabled event-driven programming, if that helps. – Scott McKenzie May 26 at 8:39
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    I don't know that library, but I fear you have to enhance it a lot for your needs. And if you want to control your leds with that 595 as well, you got a very specific task I don't see how a generic library might help. – DataFiddler May 26 at 10:54

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