Cannot blink LED on certain digital ports (11, 12, 13)


I just realised that I cannot blink the LED on digital ports 11, 12, and 13 on Arduino UNO, IDE 1.8.2.

I have found this error when I was trying to use Arduino as ISP... where these ports are essential...

BTW I also cannot blink the LED_BUILTIN (led on the board it self - L) with provided Blink example

  • Anyone has the same problem?

  • Did I fry the ports?

  • How to otherwise check the ports?

  • Is there a way to put Mega into factory defaults?


PS I have a USB dongle to rx, tx... indeed, I only need UNO to upload the sketch, could I do it via USB dongle and how?

If you're using Arduino as ISP then you are using the SPI pins, which happen to be the very pins you're complaining don't work for leds. They can't be both.