Basically, I have been following Jeremy Blum's arduino tutorial (http://www.youtube.com/watch?v=_LCCGFSMOr4) and I came to the point where I could change the voltage to control LED's brightness. However, I am facing a problem now, where any PWM pins can not change the brightness. I tried to test it by placing to different pins (range 2-7) and it doesn't do a thing. Also I unplugged everything including my computer from power extension, on which power adapter is plugged, and it did not do a thing. I noticed that the current was flowing through the LED, because its light was glowing very dimmly (not very bright I mean). The set up on a breadboard is identical to one in the tutorial I mentioned, so please do not ask me on how I set it up. Thank you!!!! PS: what kind of tests can I perform on UDOO's board to identify the fault. Thanks