1. What is the max number of ports available on an usb hub? Is it more than 7 ? if so please provide us the information on it i.e., manufacturer etc…
2. Can we cascade usb hubs? If we can, how is the
addressing handled to the device from the host? Does it induces any delay?
TI offers a variety of FS/LS hubs like TUSB2036, TUSB2046B, TUSB2077 and also a SS hub like the TUSB8040.
You can cascade the TI hubs up to 5 tiers (below is a reference picture with two tiers of hub) just take in mind the power requirements, for example, a bus-powered hub can only support self-powered hubs on its downstream ports.
The maximum propagation delay for a hub is 70ns for Full-speed hubs and 300ns for low-speed hubs.
When a device is connected to one of the hub's downstream ports, the HUB "tells" the host that there is a new device on its Port #2 (for example) and so the host starts the enumeration process with that specific device.
You can find more information in the following link http://www.ti.com/lit/an/slla314/slla314.pdf
Regards.
