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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!

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  • \$\begingroup\$ Which side of type A? Plug or socket? \$\endgroup\$
    – user3528438
    Commented Aug 9, 2017 at 15:58
  • \$\begingroup\$ 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. \$\endgroup\$
    – Tom Carpenter
    Commented Aug 9, 2017 at 16:47
  • \$\begingroup\$ @Apphone Your proposed edit seems to be answering the question. If so, please use the Your Answer field below to post your answer. \$\endgroup\$
    – Velvet
    Commented Oct 11, 2023 at 5:32

1 Answer 1

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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

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  • \$\begingroup\$ Thanks, sbell! The spec is what I was looking for, thanks for pointing me in the right direction. \$\endgroup\$
    – rockwell
    Commented Aug 10, 2017 at 13:17
  • \$\begingroup\$ @rockwell Glad I could help! If this answers your question, make sure to accept this as the correct answer \$\endgroup\$
    – sbell
    Commented Aug 10, 2017 at 17:08
  • \$\begingroup\$ 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? \$\endgroup\$
    – rockwell
    Commented Aug 27, 2017 at 23:31
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    \$\begingroup\$ @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: ww1.microchip.com/downloads/en/AppNotes/00001914B.pdf \$\endgroup\$
    – sbell
    Commented Aug 28, 2017 at 12:24
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    \$\begingroup\$ 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 (usb.org/sites/default/files/…) on page 79. \$\endgroup\$
    – Matt
    Commented Oct 12, 2019 at 22:09

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