The latest AddOhms looks at why you need a pull-up resistor when using push-buttons. This video goes into what happens when you leave a pin floating, what a floating pin means, and how the pull-up works. You can get more information about the video on the AddOhms Episode page.

[shareable]Pull-Up Resistors can be a difficult topic to understand. That’s why I made this video.[/shareable]

This tutorial is the 2nd time I’ve made a video on pull-ups. Despite being a single resistor, it can be a difficult topic for new hardware designers to understand. The pull-up video was the first video tutorial I ever made. In fact, the YouTube version uses YouTube’s “stabilization” algorithm, which gives the video a very warped feel.

AddOhms #15 shows improvements in skill over the past couple of years!

What’s another topic that I need to cover in an AddOhms Tutorial?

Fan of making things beep, blink and fly. Created AddOhms. Stream on Twitch. Video Host on element14 Presents and writing for Hackster.IO. Call sign KN6FGY.


    • Pull-Up resistors are more commonly built-in to a microcontroller. However, some do offer both. The ESP-series chips do, for example. There’s probably a signal integrity reason (aka myth) that engineers prefer pull-up to pull-down.

        • Forcing a pin to be a LOW instead of floating. Commonly you’ll see them on the gate of a MOSFET, to ensure the MOSFET is off when a microcontroller is first powered on.

  1. Nice tutorial,
    There is the other way to connect a resistor as pull-down from pin to ground and you can have a high-on signal.
    BTW you should add a reasonable value for the resistor. I prefer 10 or 20 kOhm there.

    • Steve Spence - KK4HFJ Reply

      I agree. I use pull downs much more than pull ups. Doesn’t invert the logic either. I use 10k across the board. Strong enough, with ok power consumption.

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