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Article on Pull-Up Resistors

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By Darren Hurren September 23, 2019 - 10:08am Comments (1)

Hey everyone,

I found a great artice online about the importance of pull-up resistors that I thought I would share. This was useful for my project since I was using pushbuttons. I ended up using the internal 20kOhm pullups on the SparkFun RedBoard (because of limited BreadBoard space) by setting pinMode to INPUT_PULLUP


pinMode(holdBtnPin, INPUT_PULLUP);


Here's the link to the article:


I hope helps anyone who didn't have a full understanding of Pull-Up resistors. 


  • Hi Darren,

    This is very informative as I wanted to increase my understanding of pull-up resistors. The SIK guide was brief in its discussion on this topic. I intially thought that the pin only contained 2 states but after going through the article, it appears to be 3 states: LOW, HIGH, and floating. The floating state was a surprise as I didn't realize that the pin can go randomly between LOW and HIGH. This tells me that if I'm using a pin with a pull-up resistor, then I should clearly define the pin state.

    Thanks for posting this link,


    Andrew Slade September 30, 2019 - 8:32am

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