I'm cleaning out some old junk, and stumbled onto a cable like this:

USB A male to USB A male cable

From my understanding, the USB A connector is for the host device, and 2 host devices can't communicate. So what could it be used for?

  • Does it have any electronics in the middle? – user1686 Jul 8 '19 at 21:17
  • @grawity Nope! And the casing on the connectors looks standard, I don't think there's anything tucked away in there besides a straight-through connection – Alexander - Reinstate Monica Jul 8 '19 at 21:22
  • it can serve as an extension plugged into a reduction – gamer0 Jul 8 '19 at 21:32
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    “From my understanding, the USB A connector is for the host device“ - This absolutely is not a requirement. Case in point, A printer could use Type-A female port also, which mean, your connection between a printer and PC would both be Type-A. It might be unsupported by the USB specification, but it would still work, which is often the case with cheap knockoff products. – Ramhound Jul 8 '19 at 21:55
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    Yes; I am absolutely sure, they have the same pin layout. It might specify something in the specifications but it would still work regardless if the specifications specifically specify it’s unsupported – Ramhound Jul 8 '19 at 22:32

The most common use of A to A USB cables that I have seen are direct computer-to-computer file transfer utilities.

However, there are a variety of peripherals that use A to A connectors. Here is a video I saw today using one.

Additionally, there are some devices - the ones I have seen are audio/video related - that use USB A to A. I have seen surround sound receivers with USB A connectors that are used for both reading flash drives, as well as being hooked up to a computer for configuration.

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    Do A-A M-M USB Cables for file transfers require any additional electronics? I'm interested in this application, but in the case of it being a passive device I'm not sure what the computers would see each other as in terms of USB services offered. – Scottmeup Jul 9 '19 at 7:45
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    @Scottmeup Yes. There is an integrated circuit in the cable that shows up to both computers as a device. This device is what sends and receives the data from both computers. Additionally, there is software that is needed to use the device. Here is one such device. You can see the box in the cable, where the electronics go. Link is too long, will put in another comment. – Keltari Jul 9 '19 at 8:35
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  • It's not a transfer cable (no electronics in the middle), but that video you linked is a perfect example. This just seems like a cost cutting measure, similar to HDMI over ethernet. – Alexander - Reinstate Monica Jul 9 '19 at 14:28
  • @Keltari ah I see, thank you. I was hoping there would be a passive connectivity solution over USB as is the case with ethernet or firewire cables :) – Scottmeup Jul 9 '19 at 15:06

Not that this particular cable is expected to be used for this purpose, but I have a similar cable which is used to connect a Chinese-made laser cutter to the USB port of a computer. The connection on the cutter is to a controller module, which also has a different USB port dedicated to use with a flash drive. This would imply that the PC connected port is configured differently than the flash drive port. Host to host perhaps.

  • I see. That kinda makes sense (even though it's against the USB spec), because it brings their part-count down. They can buy USB A Female connectors in twice the amount (to get a cheaper cost), and not have to pay the extra cost for USB B female connectors (as fabs charge for everything additional unique component type that the pick-and-place machine needs to be loaded with) – Alexander - Reinstate Monica Jul 8 '19 at 21:53
  • I have to use a cable like this to connect my Multimeter to my computer. I'd guess their port type choice was a cost-saving decision. I can't see any other reason they wouldn't use a more normal type-b instead. – kicken Jul 8 '19 at 23:28

You can use your cable as an extension, for example, with these reductions:

enter image description here enter image description here

USB cables are not (one)directional.

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