Go Down

Topic: Should the onboard pin 13 LED be lit by default? (Read 2662 times) previous topic - next topic

spierepf

Greetings,

When I load a do-nothing sketch onto my Arduino UNO R3, the pin 13 LED lights up. My understanding is that by default all pins are supposed to be in a high-impedance state. Have I burnt out that pin?

Peter.

nickgammon

I think we had this one recently. But the search feature isn't that good.

I think pin 13 may be HIGH but INPUT. The effect is that it will appear lit up. In other words, it is  high-impedance but with a weak pull-up. An artifact of how the bootloader leaves it.
Please post technical questions on the forum, not by personal message. Thanks!

More info: http://www.gammon.com.au/electronics

smeezekitty

The pull up may be enabled for some reason.
Try explicitly setting the pin low.
Avoid throwing electronics out as you or someone else might need them for parts or use.
Solid state rectifiers are the only REAL rectifiers.
Resistors for LEDS!

Go Up