USB Hub Controller controls how many devices?

Question

How many USB devices can one controller use? My professor said the answer is two but she has been mistaken on things before which I called her out on in class but she insisted this was correct when I tried to correct her. I know USB hubs support multiple devices but perhaps there a controller is a component inside the hub that only supports two, but the USB standards say it can support up to 97 devices if I remember correctly.

Any help on this would be great, thank you.

Answer 1

Theoretically you can have up to 127 devices connected to one host PC but there are practical power and data bandwidth limitations that would prevent that. These 127 devices can be arranged in a tiered network of hubs up to seven levels, counting the PC host as level 1 and the farthest device as level 7. The PC supplies 5 units of power to a hub. Each unit is 100 mA and each port requires a minimum of 1 unit. The hub itself consumes one, leaving 4 units for up to 4 ports. So you will never find a bus-powered hub with more than four ports.

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Answer 2

theoretically it's two, u can see them using software like amd overdrive. it'll show that one controller has been split to 2 hubs. but most of the time two devices don't use the full bandwidth of a controller so u people buy hub extenders to use more device on a single hub. and how many devices at the same time? it depends on the hub u bought and the devices u r using. cause one usb host will provide limited power. so it'll be divided among the devices unless ur hub uses external power.

Answer 3

127 is the number of devices. Practical limits are quite a bit less unless its powered hubs and low bandwidth devicses