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I make USB cables (USB-A to Mini or Micro primarily), but don't have any experience with USB-C. I would like to create a cable that has a USB-A (2.0) connector on one end, and a USB-C connector on the other (mainly for connecting keyboards to CPUs, and charging devices). How do I wire this properly (typically I use a 4-core 28AGW cable)? Thanks in advance for any help, please let me know if I need to clarify further!

rockwell
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  • Which side of type A? Plug or socket? – user3528438 Aug 09 '17 at 15:58
  • Would it not be simpler to buy such a cable, or buy a USB c to a male and get an adapter which changes the gender of the connector. Saves the effort of soldering the tiny pins on the USB c connector. – Tom Carpenter Aug 09 '17 at 16:47

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The USB 3.1 specification spells out exactly how to make this, and any other USB C -to- USB legacy cable. For a USB-A (2.0), the connection looks like:

enter image description here

sbell
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  • Thanks, sbell! The spec is what I was looking for, thanks for pointing me in the right direction. – rockwell Aug 10 '17 at 13:17
  • @rockwell Glad I could help! If this answers your question, make sure to accept this as the correct answer – sbell Aug 10 '17 at 17:08
  • On the USB-C end...if I solder the A5 pin directly to the VBUS (instead of with a resistor), will that work if the connector has a resistor built into it? – rockwell Aug 27 '17 at 23:31
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    @rockwell No, you really shouldn't. USB-C is reversible and the resistor on the CC line informs the slave device on how to route the signals correctly. The value of this resistor can also be changed to signal higher current capacity (which you probably shouldn't do). See here for more info: http://ww1.microchip.com/downloads/en/AppNotes/00001914B.pdf – sbell Aug 28 '17 at 12:24
  • Now it's USB 3.2 – endolith Jul 30 '19 at 19:52
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    The "electro-mechanical definition and requirements for USB connectors and cables" have been removed from the USB 3.2 specification and can instead be found in the USB Type-C Cable and Connector Specification (https://www.usb.org/sites/default/files/USB%20Type-C%20Spec%20R2.0%20-%20August%202019.pdf) on page 79. – Matt Oct 12 '19 at 22:09