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USB Superspeed Peripherals

NaMo_1534561
Contributor II

Hello,

When FX3 is connected to HX3 Hub on board, and FX3 will use USB3.0 SS line only to transmit the data from image sensor,

[image sensor] --LVDS-- [FPGA] --32bit bus-- [FX3] --USB SS-- [HX3]

In this case, what should I treat the USB2.0 D+/D- line?

Is it acceptable leave it open?

Could you provide recommend schematic design for reference?

Best Regards,

Naoaki Morimoto

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1 Solution
HirotakaT_91
Moderator
Moderator

Hello,

I recommend you to connect USB2.0 D+/D- lines because if USB 3.0 enumeration was failed, it will be connected by USB 2.0.

You can see schematic best practices on AN70707.

http://japan.cypress.com/documentation/application-notes/an70707-ez-usb-fx3-fx3s-hardware-design-gui...

Best regards,

Hirotaka Takayama

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3 Replies
HirotakaT_91
Moderator
Moderator

Hello,

I recommend you to connect USB2.0 D+/D- lines because if USB 3.0 enumeration was failed, it will be connected by USB 2.0.

You can see schematic best practices on AN70707.

http://japan.cypress.com/documentation/application-notes/an70707-ez-usb-fx3-fx3s-hardware-design-gui...

Best regards,

Hirotaka Takayama

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NaMo_1534561
Contributor II

Hello Takayama-san,

Thank you for your answer. It is an additional question.

As shown in the attached diagram, when connecting the FX3 to the USB 3.0 SS line only using the shared link function of the HX3, how is it appropriate to wire the D+ / D- of the FX3?

Best Regards,

Naoaki Morimoto

Capture.PNG

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Hemanth
Moderator
Moderator

Hello Morimoto-san,

When you are using DS4 as a shared link then, the 3.0 device connected (in your case, the camera) cannot be available for plug and play i.e the device has to be embedded on the board. But the 2.0 device can be removed and put back (which is done as per your schematic above).

Since you are using the shared link, you can leave the 2.0 lines of FX3 unconnected and make FX3 come up as 3.0 device always. But in the firmware you can make the change while calling connectstate API as discussed in the below KBA:

Enabling FX3 Only for USB 3.0 Applications – KBA219491

Regards,

Hemanth

Hemanth
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