I've always been a huge fan of more ruggedized connector offerings. As a novelty side-project I've decided to build some of my own USB cables for use with my peripherals, but I decided building a generic USB 2.0 cable (480 Mbps) was too easy and boring (and also is something I've done before already). While browsing some listing for generic aviation (GX series) connectors, I found that a 16mm (GX16) connector can have up to 9 pins, the required pin count for a USB 3.1 Gen 1 (formerly USB 3.0 SuperSpeed, same 5Gbps signaling).
Generic GX16, 9-pin Connector
In order to make custom USB cables, you would need some basic components:
Since USB is already backwards compatible, I hate having "underpowered" cables costing me time and annoyance, and thus I cannot settle for a generic USB 2.0 cable. Now, the issue with building a custom USB 3.1 Gen 1 cable is that with its signaling rate of 5Gbps, the amount of precision required to make a reliable cable is far beyond that of a USB 2.0 cable. Anybody can make a 2.0 cable work, you hardly need to pay attention to the wiring since it is so lenient!
To understand what I was getting into, I began digging for the USB specification documents. The relevant documents for this particular endeavor are the following:
Now we need to determine what kind of basic components we need to build a cable that is to spec. In the USB 3.1 spec sheet you can first find the required cable type for this kind of application:
The spec calls for a total of 10 wires, composed of the following wire assignments:
Note that it calls for shielded twisted pairs + a metal braid enclosing the entire wire assembly. This tells us what kind of cable we need to purchase. After some digging, I was able to find an AliExpress listing that has the required cabling. We also need to buy the right USB (male plugs): most commercially available USB plug breakouts don't have the right number of pins. The USB-C spec also requires that for a USB-C/USB-A 3.1 Gen 1 cable, the USB-C side of a cable have a 56kOhm pull-up resistor on the USB-C side of things. It took quite a while to track down the right listings, but I've gathered a couple with the right number of pins and the proper electrical setup for this to work.
The following is the actual wiring spec required for a USB-C/USB-A (USB 3.1 Gen 1) cable.
It's relatively straightforward to wire up, although care must be taken to ensure all the electromechanical specifications are met. Based on what the AliExpress listings provide for the pinouts, they will have the correct wiring for a full-speed USB 3.1 Gen 1 5Gbps cable, so we shall see how that pans out. I will update this posting as this side project progresses. It's been a rather involved endeavor to figure this out, so hopefully this can help somebody.

Generic GX16, 9-pin Connector
In order to make custom USB cables, you would need some basic components:
- 2 x USB male plug of desired variety
- USB cable (4 core wire for USB 2.0, 9 for USB 3.1 Gen 1)
- Any inter-cable termination/connectors
Since USB is already backwards compatible, I hate having "underpowered" cables costing me time and annoyance, and thus I cannot settle for a generic USB 2.0 cable. Now, the issue with building a custom USB 3.1 Gen 1 cable is that with its signaling rate of 5Gbps, the amount of precision required to make a reliable cable is far beyond that of a USB 2.0 cable. Anybody can make a 2.0 cable work, you hardly need to pay attention to the wiring since it is so lenient!
To understand what I was getting into, I began digging for the USB specification documents. The relevant documents for this particular endeavor are the following:
- Universal Serial Bus Type-C Cable and Connector Specification, Release 2.0 (August 2019)
- USB 3.1 Legacy Cable and Connector Specification, Revision 1.0 (September 2017)
Now we need to determine what kind of basic components we need to build a cable that is to spec. In the USB 3.1 spec sheet you can first find the required cable type for this kind of application:

The spec calls for a total of 10 wires, composed of the following wire assignments:

Note that it calls for shielded twisted pairs + a metal braid enclosing the entire wire assembly. This tells us what kind of cable we need to purchase. After some digging, I was able to find an AliExpress listing that has the required cabling. We also need to buy the right USB (male plugs): most commercially available USB plug breakouts don't have the right number of pins. The USB-C spec also requires that for a USB-C/USB-A 3.1 Gen 1 cable, the USB-C side of a cable have a 56kOhm pull-up resistor on the USB-C side of things. It took quite a while to track down the right listings, but I've gathered a couple with the right number of pins and the proper electrical setup for this to work.
The following is the actual wiring spec required for a USB-C/USB-A (USB 3.1 Gen 1) cable.
