Random Nerd Tutorials

Arduino – Pull-Up Resistors


Today I’ll talk about Arduino built in Pull-Up resistors. I think that probably some of you already used this Arduino feature (It’s actually on all ATmega 328 microcontroller) but never realized what It was.Pull_Up_Resistor_Circuit

“A pull-up resistor weakly “pulls” the voltage of the wire it is connected to towards its voltage source level when the other components on the line are inactive. When all other connections on the line are inactive, they are high-impedance and act like they are disconnected.

Since the other components act as though they are disconnected, the circuit acts as though it is disconnected, and the pull-up resistor brings the wire up to the high logic level.

When another component on the line goes active, it will override the high logic level set by the pull-up resistor. The pull-up resistor ensures that the wire is at a defined logic level even if no active devices are connected to it.”  from wikipedia

So if you use this feature you can save a few resistors in your projects!

This video explains really simple what it is and how it works in your Arduino!

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