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I'm using VL805 USB3.0 Host Controller which takes one lane of PCIe and outputs 4 ports of USB3.2 Gen 1 (5Gbps) .

I have been looking for a reference design that uses two of these ports for USB-C Connector, and leave the other two for regular USB3.2 Gen1 TypeA connectors.

For example, I want to use the signals which previously were used for two USB3.2 Gen1 TypeA ports: enter image description here

for one USB-C connector: enter image description here

I see that by doing this, I will still have CC1, CC2, SBU1, SBU2 pins not connected to anything, how do I deal with them?

Also, I'd love if someone can share a design guide for such application.

Note: should I worry about the Host (VL805 chip) of being capable of providing such function or just rely on the fact that it's capable of providing me with two native USB3.2 Gen1 ports?

Although I have zero experience with designing platforms with Type-C, I think that VL805 chip must support the fact that Type-C cable could be flipped. I hope someone can fix me if i was mistaken.

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  • \$\begingroup\$ A single USB-C connector would use only one of the USB ports, not two. \$\endgroup\$ Jan 22, 2023 at 12:43
  • \$\begingroup\$ you mean one of the USB 2.0 ports? \$\endgroup\$ Jan 22, 2023 at 12:45
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    \$\begingroup\$ No, a single USB 3.0 port. The SS Tx/Rx pins would need a highspeed multiplexer and extra detection and power control logic to select whether they go to TxRx1+/- or TxRx2+/-. \$\endgroup\$ Jan 22, 2023 at 12:49

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The VL805 does not support native USB Type-C. What you want to do is not possible with this IC.

The reason for this is rather simple: The VL805 was introduced in 2012, while the USB Type-C specification was only released in 2014. There's no way for the VL805 to support a specification that didn't exist when it was designed. As a result, you simply can't combine two of its USB 3.0 ports to make one multi-lane Type-C port.

You can instead wire a single USB 3.0 5Gbps link to the Type-C connector, using only one of the two transmit and receive lanes available on the connector. This is how USB 3.0 Type-A to Type-C adapter cables work. Compatibility and link speed will of course suffer as a result. USB-C devices connected to this port should be able to detect which lane is being used and multiplex it accordingly, though. (Otherwise, USB 3.0 Type-A to Type-C cables would not work at all.)

Example wiring diagram

If you really need native multi-lane Type-C, you need to use a different IC that actually supports this.

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  • \$\begingroup\$ Thanks. that was very insightful. \$\endgroup\$ Jan 22, 2023 at 13:30
  • \$\begingroup\$ Hi Jonathan, can you please check my question update? \$\endgroup\$ Feb 19, 2023 at 10:53
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    \$\begingroup\$ This question has already been answered - if you want to ask another question, please create a new question. I'd recommend you to undo your recent edits (the "Update") so that the new question won't accidentally be marked as a duplicate. You could, for example, use the following title for the new question: "How can I allow rotation of a USB-C port if I only have a single USB 3.0 lane connected to it?" Additionally, it'd be good if you made it clear that it's a follow-up question and linked to the old question. See: meta.stackoverflow.com/questions/254521/… \$\endgroup\$ Feb 20, 2023 at 16:58

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