In theory, USB cables that support data transfer should have the ‘trident fork’ logo, but in practice the cheap stuff from China uses that logo whether it has data capabilities or not. Turns out there’s no easy way to do that by just looking at the cable. You’re probably wondering now: how do i know which ones of these are usable for data transfer, and which ones can you only use to charge devices? If you’re like me, and you tend to accumulate all kinds of gadgets over the years you’ll probably have a drawer full of Micro USB cables like this: The same thing also happens when you’re trying to send programs to a development board, like an Arduino or ESP32 device. When you try to use one of those cables (without data transfer wires) your phone or e-reader will be charged, but you can’t send data over from your laptop.

Especially in cheaper cables, that you might get when ordering stuff from sites like AliExpress, these wires might be missing to reduce cost. However, even though these pins are here, doesn’t mean that the wires for data transfer (pins 2 and 3) are necessarily available. Pin 1 and 4 carry the power (for example, to charge your phone), pins 2 and 3 are used for data transfer (like sending photos). Why is that? Let’s take a look at the pins of a USB-A connector: Image adapted from Simon Eugster / Wikimedia Commons / CC-BY-SA One of these will work, and the other will not.

However, something funny happens when you try to use these cables to send over data to a device, like sending music to your (Android) smartphone or books to your e-reader (like a Kindle or Kobo). They are both black, have a USB-A connector on one side and a Micro USB connector on the other side, and feature the ‘trident’ USB logo.

Here’s a seemingly simple question, what is the difference between these two Micro USB to USB-A cables?

Usb 2 vs usb 3 what they look like