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Understanding HIGH and LOW Arduino Pin States

If you are just getting started with Arduino, you might be wondering what the heck all this HIGH and LOW stuff everyone is talking about really means.

At first I just figured everyone using micro-controllers was just on some type of emotional roller-coaster, until I began to realize that HIGH and LOW are actually abstractions.

But let us not talk in abstractions – let us talk in concrete numbers and get down to the bottom of what HIGH and LOW actually mean.

This Tutorial Will Include:

  1. What the heck is a PIN state?
  2. What are the values for Arduino Pin States?
  3. Practical Application: What do we see in practice?


  1. […] So all we have to do is bring the pin LOW – which is as easy to connecting it to ground through a pushbutton.  So when the button is not pressed, the pin is in its normal state.  When the pushbutton is pressed, the pin “see’s” ground voltage (i.e. 0 volts), and is brought LOW – which according to the documentation will reset the Arduino for us. […]

  2. Avatar Mehmet Şüküroğlu on September 12, 2016 at 8:21 pm

    you have not show any connection to digital pin2 in last part of video.

    • Avatar MICHAEL JAMES on June 2, 2017 at 4:46 pm

      Your right! Thanks for pointing that out. The center pin of the potentiometer should also be connected to digital pin 2.

  3. Avatar Lyndon Mansell on June 2, 2017 at 4:20 pm

    As the other person said, there is something wrong with the code. you quote D2 and then still read voltage at A0. Is this a sample of your free training ?

    • Avatar MICHAEL JAMES on June 2, 2017 at 4:47 pm

      Thanks for pointing this out Lyndon. I forget to show that the center pin of the potentiometer should also be connected to digital pin 2. I will have to rework that video.

  4. […] analog sensors, digital sensors only output two voltages: High & Low. Usually the high voltage is the same as your power rail, and the low voltage is your system […]

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