Can't even get the Blink Sketch to work on Leonardo

I can't even get the Blink sketch to work on a Leonardo board.

I chose the Leonardo board (which is recognised) but can't select the port. This is greyed out. When I load the sketch I get an error message that the board is not found on the com port selected.

Any ideas?

What happens if you press the reset button on the Leonardo?


I tried that, but nothing changes. Is it normal for the com port display to be greyed out for a Leonardo? I can see the com port dispayed with my Uno and Nano.

I don't use Windows so I can't offer any other suggestions. My Leonardo works fine on Linux.

Maybe you would attract the attention of someone who can help if your Title reflected the problem - for example "COM port display greyed out with Leonardo"

If you edit your Original Post you can change the Title.


Check here :

Yes, with the 32U4, a sketch can overwrite the bootloader and almost "brick" the board. But there is a procedure for restoring it, I've had to do that a few times with the Pro Micro. Basically, you have to do a manual timed release of the reset button, at the same time as uploading to the board.

You may be trying to use a charging cable as opposed to a full on USB cord. Charging cables look the same but have no digital lines in them.

-jim lee

COM port greyed out means your PC doesn't recognize the Leonardo. Either there is a problem with your driver or your cable as mentioned or your USB port.

Restart your PC, reinstall the driver, use another USB port, use another cable, try on another PC.

If all that failed perhaps you have a counterfeit Arduino that doesn't work with the official driver. Ask your supplier or check their website to sew if you need a specific driver.

PS:On my windows 10 PC "COM1" port is always available regardless of what I have connected. I don't know if its specific to me, but if you have no ports available perhaps that means there's something wrong with your operating system.

Thanks for all these great replies guys. That gives me plenty to try. Cheers.

It was the cable! I had bought the board without a cable and just plugged in the first one that came to hand. It was the cable that came with one of those power banks! Never realised these were no good.

A lesson learned. Thanks again for the help :slight_smile: