GPIO Pin to LED

[ambivalent]

Hallo,

I was wondering if anything else is required to power an LED beyond setting the pin to output and high?
I have it set up exactly as it is pictured here: https://projects.drogon.net/wp-content/ ... ample2.jpg I'm fairly confident that the circuitry is correct, as I powered it from the 3.3v at Pin 1 prior.

[joan]

No.

Doesn't it light? Try switching the connections (LEDs are directional).

[PiGraham]

You only need LED and resistor.
You can generally assume an LED will drop 2V.
The GPIO can drive max 16mA.
If you play safe and design for 10mA your resistor should drop 1.2V @ 10mA
R = 1.2/0.01 = 120R

If the resistor value is too high you won't see the LED light.
If it's too low you may blow your Pi.

Basics: Have you measured the voltage on the output when unconnected? Does it go to 3.3V?
Does the LED light if you connect it, with series resistor, direct to the 3.3V power rails?
Check the markings. Is the LED the right way round?
At 3.3V you can just try reversing the LED. At higher voltages watch the VR limit. You can blow LEDs quite easily

[Grahameaston]

Hi
I am having the same problem . LED works coupled to the 3.3v supply and the program / file / script runs with no errors but the led will not light.
I have the correct GPIO module that I have downloaded and inserted the GPIO "cleanup to the pin I am using.

Any advice would be greatfully received

Graham

[ambivalent]

It turns out it was my code. PIN 16 (the onboard LED) worked correctly, so I had (regrettably) assumed that other pins would work as well.