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Power-only micro USB leads are a thing

Posted at 10:00 on 20 November 2023

So I took delivery of a new Arduino Micro at the weekend. Since this is my first foray into Arduino development, naturally I had to download and install the Arduino IDE and then plug the thing in. So I got out a micro USB lead and plugged it into the computer.

The LEDs on the board came on as they're supposed to. All well and good so far. But when you connect an Arduino to your computer and load up the Arduino IDE, it's supposed to show up in the "Select Board" dropdown menu at the top:

Mine didn't:

I tried adding it manually through the "Select other board and port..." option:

No ports detected. The "Ports" option in the "Tools" menu was greyed out.

I tried unplugging and replugging it. The computer didn't beep as it normally does when you plug something in. I tried looking in the Windows device manager ... not a trace of it. I tried updating and installing drivers ... again, nothing. I tried a second micro-USB lead ... yet again, nothing. I tried resetting it. I tried updating all my Windows device drivers. Again, nothing. As far as I could tell, I had just spent twenty pounds on a brick.

It was later in the evening that I tried it with a third lead ... to find that this time it worked.

It turns out that power-only micro USB leads are a thing. Most USB cables have four conductors inside them -- two for power and two for data -- but both of the ones that I had originally tried were power-only ones. In fact out of the seven spare micro USB cables that I have accumulated over the years, both of the first two that I had tried had only two. Cutting one of them in two and stripping back the insulation showed that this indeed was the case:

To add insult to injury, this one has the USB trident logo on it. If it doesn't support data transfer, it's not supposed to. Thanks to cheap-and-nasty knock-offs such as this, there's no reliable way to tell at a glance which micro USB cables support data transfer and which ones do not. Cutting the second failed cable in two confirmed that it, too, had only two conductors.

Fortunately all my other micro USB leads were fine, so I'm now ready to get my teeth into some proper Arduino hacking in my spare time. But as for the two power-only ones, to avoid any further confusion, I've thrown them away.