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Author Topic: Shift Register Auto Pull Up/Down  (Read 432 times)
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Do Shift Registers, Multiplexers and Demultiplexers have any kind of built in pull-up or pull-down circuitry for their input pins (like the Arduino) ? Do any makes or models work differently in this regard? As for the Arduino, is this this function built into the Atmel chip, or is it external to the chip? I am primarily using the Micro, Leonardo, or Uno in my prototyping.

I am making a somewhat simple USB Remote Control, and the only task the Arduino has is to forward button presses to the host computer. All this I have worked out pretty well.  I've learned how to use external pull-up circuits with multiple buttons. I also understand that the Arduino a has built in circuitry to handle this for me, and that seems to work too.  Using built in circuits will greatly simplify my design.

But I would like to add as many buttons as possible, which means using some form of Shift In register, and I would like to know if I will have to revert to making my own external pull up/down circuits just to make my buttons work.

It also seems that making such a "button board" should be a well beaten path.  Is there any design patterns I should be using to simplify my designs? I know there are prefabricated boards with multiple micro switches built in, but I want to build a board that can hook up to an arbitrary # of buttons of arbitrary type (Arcade Buttons for example).

Thanks,
Kyle
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Quote
Do Shift Registers, Multiplexers and Demultiplexers have any kind of built in pull-up or pull-down circuitry for their input pins (like the Arduino)
No.
The programmable pull up is mainly reserved for processors.

Yes it is well beaten but so trivial that there is little options, just have a pull up and switch between input and ground.
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