My PWM ports don't seem to work.

Hi, I recently built the LED stop lamp exercise to get me back into the swing of things and that worked fine using lower PWM ports. But when I tried the multi colored LED using the 9, 10, 11 PWM ports the exercise would not work. I tried a tutorial off of youtube yesterday that would simply light the LED and scroll through the 3 colors, Red, Green, Blue. When using my analog VOM the LED does light the three colors.

I am using the Arduino UNO board and do not get any error messages that I can tell. Has anyone experienced something like this before? I updated to the latest software yesterday.

Is the board broken?

No code, no schematic, no help.

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These steps may also save you some unnecessary time and effort in the forum.


  • Check you have a COMMON GROUND where required.

  • Where possible use USB 2.0 ports or a USB 2.0 POWERED HUB to rule out USB 3.0 issues.

  • Try other computers where possible.

  • Try other USB leads where possible.

  • You may not have the correct driver installed. CH340/341 or CP2102

  • There may be a problem with the board check your wiring first.

  • Remove any items connected to pins 0 and 1.

  • Ensure you turn off any additional security / antivirus just to test.

  • There may be a problem with the PC try RESTARTING it.

  • You may be selecting the wrong COM port.

  • Avoid cloud/network based installations where possible OR ensure your Network/Cloud software is RUNNING.

  • Clear your browsers CACHE.

  • Close the IDE before using any other serial programs.

  • Preferably install IDE’s as ADMINISTRATOR or your OS equivalent
    Performing the above actions may help resolve your problem without further help.


thanks, will post more next time.

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