What latency do Cypress Hub components add to USB Packet Transfers?

[GrCa_1363456]

Does Cypress state the minimum, maximum or expected typical throughput latency of packets?

I didn’t find a Technical Reference Manual for Cypress’ Hubs.

Aside: I did find a nice collateral guide for FX3 which includes a TRM @ https://www.cypress.com/applications/ez-usb-fx3-superspeed-usb-30-peripheral-controller-collateral-g...

Greg

[Sananya_14]

Hello Greg,

Could you kindly tell us for which hub part you want to know the packet latency? Generally the values are within the USB 2.0 and USB 3.0 specification.

Best Regards,
Sananya

[GrCa_1363456]

Sanaya,

Thank you for considering my question.

I’m specifically interested in latency along the physical superspeed path (SS lines) through the HX3, CYUSB4357-BZXC. As the HX3 is a Hub and not a Switch, I understand there will be buffering delay and may be some contention with other traffic.

• What is the minimum amount of time between the first bit of a packet entering the HX3 and that first bit leaving the HX3?
• Is there a maximum amount of time between the first bit of a packet entering the HX3 and that first bit leaving the HX3 for an Isochronous mode packet?
• What conditions might affect the transfer of an Isochronous packet?

Greg

[Sananya_14 · Accepted solution]

Hi Greg,

-The minimum and maximum times are as per the USB 3.1 spec, please refer to Table 10-19 in the spec for the values.

-For Isochronous packet, the bandwidth allocated for the transfer will depend on other downstream devices connected on the hub and if they use the isochronous endpoint as well.

Best Regards,

Sananya