HX3: self-powered vs bus powered

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DeAl_292241
Level 3
Level 3
First solution authored 10 replies posted 10 questions asked

Hi,

I would like to know how to set between self-powered and bus-powered types inside the descriptors of the HX3 ?

Thanks,

Denis Alain, Eng.

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1 Solution

Hello Denis,

Your understanding is correct. As per the USB Spec, the hub powered mode should be specified in the Configuration Descriptor. However, HX3 doesnt support bus powered mode and since it is a fixed firmware part, the mode is fixed as self-powered in the descriptor.

Best Regards,

Sananya

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3 Replies
DeAl_292241
Level 3
Level 3
First solution authored 10 replies posted 10 questions asked

Hi,

I think my question is more a USB spec question, since I'm not even sure if the HUB has to indicate between these two modes. Going through the USB 2.0 spec, I don't see the mechanism. It should be there, since the host needs to know if the total power budget of all USB devices and USB devices don't change their respective descriptors between the 2x cases.


Any help?

Thanks,
Denis

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Hello Denis,

Your understanding is correct. As per the USB Spec, the hub powered mode should be specified in the Configuration Descriptor. However, HX3 doesnt support bus powered mode and since it is a fixed firmware part, the mode is fixed as self-powered in the descriptor.

Best Regards,

Sananya

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DeAl_292241
Level 3
Level 3
First solution authored 10 replies posted 10 questions asked

Ok, thanks Sananya. We will use it as self-powered mode, so no problem for us.

Best Regards,

Denis

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