Does USB 3.0 hubs implement transaction translator with USB 1.1 devices?

[Maxence_1]

Hi,

I have a USB 1.1 device (Full-speed device) which when plugged into a USB 2.0 hub, operates as hi-speed on the upstream ports of the hub, and I can write a message on the USB bus each 0.125ms. I am not an expert, but I read about the Transaction translator between USB 2.0 hosts and USB 1.1 devices and I think this behaviour is related to that.

However, when I plug this same device into a USB 3.0 hub (on another computer), I can only write one message each 1ms. So my device is operating as a Full-Speed device on the 3.0 host. I read here that USB 3.0 hubs do not currently perform transaction translator to super-speed for USB 2.0 devices, but does it perform transaction translator from full-speed to hi-speed, for USB 1.1 devices ?

Thank you in advance for your answers

 

[Lutfij]

Worth a read here and here.

 

[Maxence_1]

Worth a read here and here.

Thanks for your answer. I have read your links and it indeed told me that the translation between USB 2.0 and 3.0 is not implemented yet. However I still cannot find information about USB 1.1. Reading the USB 3.0 specifications told me that a USB 3.0 hub is a combination of a SuperSpeed hub and a USB 2.0 hub. Knowing that, I assume the 2.0 hub of the 3.0 hub provides a transaction translator with Low/Full Speed devices. But the things seem not to be as easy as I don't observe such result with my 1.1 device.

 

[Maxence_1]

This could summarize my issue :

USB 2.0 host controller <--- Hi-Speed (TT) ---> USB 2.0 hub <---Full-Speed----> USB 1.1 Full-Speed device

USB 3.0 host controller <--- SuperSpeed ---> USB 3.0 hub <---SuperSpeed----> USB 3.0 device
USB 3.0 host controller <--- Hi-Speed (No TT) ---> USB 3.0 hub <---Hi-Speed----> USB 2.0 Hi-Speed device
USB 3.0 host controller <--- ????????? ---> USB 3.0 hub <---Full-Speed----> USB 1.1 Full-Speed device

 

[Maxence_1]

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