Connecting arduino uno 5v output directly to digital i/o?

Hey I'm just starting with the arduino uno and electronics in general, so I just have a simple question to ask.

Can I connect the arduino uno 5v output through a button directly to a digital i/o without ruining the board? - Or do I need to have a resistance in between? If so how much resistance is needed?

Thanks in advance


Hi Jesper,

Welcome in Arduino land.

Please take some time to go throught the tutorial section like - - as there is a lot to learn. IN a few days you will learn a lot, and although the sketches may seem simple there is a lot of know how in them.
(you will find the answer to your question in the above link)

Another site with good tutorials is ladyada - Arduino Tutorial - Learn electronics and microcontrollers using Arduino! -

For more know how about electronics - -

Have fun, and if there are questions just let us know.

Okay basically they do the same thing as I have done - except the placement of the pulldown - which I have placed at the same leg as the 5v is connected to and then to ground. But that shouldn't make a difference?

But that shouldn't make a difference?

Yes that makes all the difference with out the pull down it will simply not work. The input will float:-

Hmm okay - makes sense. So just to be sure, I should have a pulldown on both my outputs and inputs, and not only my inputs?

Only inputs.

Thanks for the help both of you :smiley: