CYUSB4347 Hub attached 2x 5Gbps device on DonwStream ports with 10Gbps UpStream Host.

[Ping]

Dear Sir/Madam,

Please help to check the CYUSB4347 USB3.1 Gen2 (10Gbps) Hub is there suitable for the below application.

CYUSB4347's UpStream port attached to PC Host Port with USB3.1 Gen2 (10Gbps).

A USB3.0 Device (5Gbps operate in Isochronous Mode with 3Gbps payload) connected to CYUSB4347 DS4 port, that is works fine on data transfer from Device to PC.

But when attaching one more USB3.0 Device (same device as above) connected to CYUSB4347 DS5 port (i.e. 2 devices connected to CYUSB4347 DS ports at the same time), this device cannot get enough resources from PC Host for data transfer.

Please help to evaluate.

Best regards,

Ping 

[MallikaK_22 · Accepted solution]

Hi Ping,

When multiple simultaneous data transfers occur, it can result in sharing of the USB bus bandwidth.

But how much is the effect being seen? Please describe the issue.

Also, you can stop all data transfers on the USB bus except on DS5 for seeing USB 3.1 Gen 2 data
transfer speed.

Regards,

Mallika

[Ping]

Hi Mallika,

In my system, I have two USB3.0 devices connected to the CYUSB4347 USB3.1 HUB. The upstream of the HUB is connected to PC with USB 3.1 GEN2 host controller. For our USB3.0 devices, they would each generate 3.0Gbps traffic (Isochronous mode) and the sum is about 6.0Gbps. I would expect the HUB can support such traffic from devices to host PC. I try to start the devices one by one in host side. The 1st startup device is ok and can stream data as expected. However, system doesn't allow to start the 2nd device. The reason is lack of resource. I suspect it's somehow related to the 3.0Gbps bandwidth requested by my device. Then, I kick off the experiment again with lower traffic requirement from both my devices. This time, I reduce the traffic from 3.0Gbps to 1.2Gbps on both devices. In this scenerio, both devices can be started successfully and can stream data at expected bit rate.

Could you help to explain on the experiment result? It looks like the HUB can't deliver 10Gbps traffic with multiple USB3.0 devices attached. Any comment?

I find the term "Multiple INs" in USB3.1 spec. It's a protocol that would affect overall transfer bandwidth in the HUB when a USB3.0 device is attached to the USB3.1 HUB. Does CYUSB4347 supports "Multiple INs"?

Best regards,

Ping