Two Grounds connecting?

// Er, hi, I’m new. Sorry if this is in the wrong space.

Will the Arduino or LED be damaged if I supply ground to both the anodes and cathodes of LED?

Thanks,
~Noodle (Australia)

this will short-circuit the arduino and heat it up. If you leave it like that it can possibly boil and explode. :wink:

No, seriously, nothing like that will happen.

Grounding both pins of a led will effectively turn it off, as well as setting both pins to 5v.

You can actually use 2 output pins to drive a led. You wire a led and a 220ohm resistor in series, then you stick each of the unattached pins in one output. when you set the right outputs to LOW and HIGH respectively, a difference of potential will be created across the led and it will light up.

The reason I asked this was because I was contemplating the theory behind multiplexing, using only digital outputs, no IC’s. I now fully understand how I can control it, and that it won’t fiztits up if two grounds are connected.

Thanks handi.