3
\$\begingroup\$

I am working on a prototype device and I will have a daughter-board mounted at an odd angle in a custom enclosure. I need to get a USB signal, and a few extra GPIO type wires, over to the board. I can't really do a board-to-board connector and will almost certainly need a cable. It only needs to run a few inches, about 2-4. It needs to be reliable and easy to assemble, no stripping an existing fine wires. I don't want an actual USB connector, I'm looking for something slightly more permanent.

I had a few thoughts and am not sure what is best.

  1. Use a ribbon cable and IDC connector. Noise might be a problem but I'm not sure. I could wrap with a foil tape, but it's still not a twisted pair and might be slower.

  2. Use a shielded USB cable that is terminated with a female crimp header, like you see on a motherboard for front panel USB. This seems like a good option, but I can't find a source of really short cables. It also wouldn't have the extra connections.

  3. Use a SATA connector and cable. It's well shielded and readily available. It's not twisted pair though. Will that be a big deal over a few inches? How terrible is it to use a standardized cable for something completely different?

Open to suggestions and corrections.

|improve this question
\$\endgroup\$
  • \$\begingroup\$ PC motherboard vendors have USB coming off standard .1" header sometimes for front panel expansions, relocate ports, etc. Can you use individual wires instead of a ribbon cable and twist the data pair yourself? \$\endgroup\$ – dext0rb Aug 13 '14 at 17:25
  • \$\begingroup\$ A SATA cable in all likelihood provides a higher quality transmission line than a USB cable, since it has to support higher datarates. The differential impedance spec is slightly different (100 ohms for SATA vs. 90 ohms for USB) but it shouldn't matter for your application. \$\endgroup\$ – mng Aug 13 '14 at 18:05
  • 1
    \$\begingroup\$ It might help to answer: is it low-speed USB (1.2Mbits), full-speed USB (12Mbits), highs-speed USB (480Mbits) or USB 3? \$\endgroup\$ – gbulmer Aug 13 '14 at 18:45
  • \$\begingroup\$ Thanks. Its full-speed USB. I'd avoid twisting my own for time's sake, but I won't rule it out. \$\endgroup\$ – Evan Edstrom Aug 13 '14 at 20:28
  • \$\begingroup\$ There are roughly a gazillion various options available in the Digi-key catalog for connectors. \$\endgroup\$ – whatsisname Aug 14 '14 at 2:33
2
\$\begingroup\$

For a length of a few inches, twisted pair or not probably won't matter - ribbon cable will likely work just fine in most environments.

For option 2, I assume you mean something like this? (though probably with both ends female) enter image description here

Those cables should work fine if you can find a source in the length you need - really short ones are probably uncommon though. The fact that those cables aren't twisted for about an inch on each end is why I suspect you'd be fine without twisted pairs.

Those cables are for 2 USB ports, and are keyed so they can't be plugged in backwards - so you could use one set for your USB signal, and the other for the GPIO pins.

|improve this answer
\$\endgroup\$
  • \$\begingroup\$ Thank you. The photo is just what I was talking about. Thank you for confirming a non-twisted cable would probably be okay for a short run like this, I'll probably give ribbon cable a go. \$\endgroup\$ – Evan Edstrom Aug 13 '14 at 20:29

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.