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Explorer
Explorer
1,958 Views
Registered: ‎07-23-2009

Zynq ultrascale+ USB2 and USB3 device mutual support

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Dear all,

 

I am gathering information for our new project which shall involve Ultrascale+ Zynq device with USB 2, USB 3 and Ethernet capabilities.

 

We need a USB 3 device able to communicate with a PC. the problem is that we would like to have it also compatible with older USB 2.0 PC. as far as I read in the UG1085 the zynq ultrascale has two independent USB ports connected with the Processing System both capable of USB2 or 3 interfaces. On page 857 is clearly written that the each PS USB port "Provides simultaneous operation of the USB 2.0 and USB 3.0 interfaces (only in host mode)."

Does that mean that if our Device is configured as USB3 is not compatible with USB2 hosts (like old PCs)?

Did I understand correctly the UG1085

 

If yes, a solution might be to use both USB PS ports one configured as USB3 device and one configured as USB2 device but both connected on the same USB3 connector (type B for example). in this way when our device is connected to a USB3 host the firsst PS USB port is activated and performs USB3 transfers, but when our device is connected to a USB2 host, the second PS USB port is activated performing USB2 transfers.

 

Is it feasible? we are just exploring our options and before proceeding to the designing phase of the board we would gather as more information as possible.

 

Thanks

Emanuele

 

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Xilinx Employee
Xilinx Employee
2,202 Views
Registered: ‎01-21-2008

Re: Zynq ultrascale+ USB2 and USB3 device mutual support

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Xilinx USB0/1 SoC interface (TRM.UG1085.page.854.chapter-31 - Table 31-1: USB 3.0 Controller Configurations) is USB3.0 compliance certified. So this means that your concern regarding USB speed device compatibility such as USB3.0 (SuperSpeed), or USB2.0 (HS) or USB1.1/1.0r USB1.0 (FS) speed does support all speed in our interface.

 

Basically USB 3.0 is backward compatible with existing USB 2.0 infrastructure. This means in USB3.0 interface it, includes h/w for both (USB 3.0 as well as USB2.0) the standards; have a look ZCU102 schematic for more help regarding h/w structure and external ULPI PHY requirements for USB3.0 IF.

 

Regarding your query over the device mode, fall-back speed, i.e. if you set the highest speed as “super-speed”, in Device-tree, then your Mass storage device detection from xHCI drivers, will set it according to the device connected to the USB0/1 port accordingly.  For example if you connect “HIGH-SPEED” (HS) device to the USB0/1 USB3.0 capable interface, then xHCI driver will fall back to the HS speed accordingly which is USB2.0 compatible Speed (HS). In Device mode interface speed selection will depends on the HOST PC interface. If HOST PC is SuperSpeed capable, then ZynqMP USB0/1 IF will hold the SS speed at the start and GTR will give you  respective speed as it is mentioned in the TRM.UG1085.page.857.USB controller features.

 

4 Replies
Scholar u4223374
Scholar
1,952 Views
Registered: ‎04-26-2015

Re: Zynq ultrascale+ USB2 and USB3 device mutual support

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It'll be able to do USB2.0 in device mode; it just can't do USB2.0 and USB3.0 simultaneously in that mode (a single device being both USB2.0 and USB3.0 at the same time doesn't make much sense).

 

USB3.0 is backward-compatible with USB2.0; if it couldn't drop back to USB2.0 mode then it wouldn't be a USB3.0 controller.

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Explorer
Explorer
1,950 Views
Registered: ‎07-23-2009

Re: Zynq ultrascale+ USB2 and USB3 device mutual support

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That means: after connection the PS is able to recognize if our ZYnq ultrascale device is connected to an USB 2 or USB3 host and then turn on the GTR transceivers (in case of USB3) or the external USB2 transceiver? I got these doubts because the UG1085 distinguish between USB 2 and 3 host and device configuration.
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Explorer
Explorer
1,892 Views
Registered: ‎07-23-2009

Re: Zynq ultrascale+ USB2 and USB3 device mutual support

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Is there a chance to have a confirmation from a Xilinx employee or somebody who tested it on hardware?

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Xilinx Employee
Xilinx Employee
2,203 Views
Registered: ‎01-21-2008

Re: Zynq ultrascale+ USB2 and USB3 device mutual support

Jump to solution

Xilinx USB0/1 SoC interface (TRM.UG1085.page.854.chapter-31 - Table 31-1: USB 3.0 Controller Configurations) is USB3.0 compliance certified. So this means that your concern regarding USB speed device compatibility such as USB3.0 (SuperSpeed), or USB2.0 (HS) or USB1.1/1.0r USB1.0 (FS) speed does support all speed in our interface.

 

Basically USB 3.0 is backward compatible with existing USB 2.0 infrastructure. This means in USB3.0 interface it, includes h/w for both (USB 3.0 as well as USB2.0) the standards; have a look ZCU102 schematic for more help regarding h/w structure and external ULPI PHY requirements for USB3.0 IF.

 

Regarding your query over the device mode, fall-back speed, i.e. if you set the highest speed as “super-speed”, in Device-tree, then your Mass storage device detection from xHCI drivers, will set it according to the device connected to the USB0/1 port accordingly.  For example if you connect “HIGH-SPEED” (HS) device to the USB0/1 USB3.0 capable interface, then xHCI driver will fall back to the HS speed accordingly which is USB2.0 compatible Speed (HS). In Device mode interface speed selection will depends on the HOST PC interface. If HOST PC is SuperSpeed capable, then ZynqMP USB0/1 IF will hold the SS speed at the start and GTR will give you  respective speed as it is mentioned in the TRM.UG1085.page.857.USB controller features.