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Monday, July 9, 2018

What is the maximum number of USB devices a host controller can handle?

What is the maximum number of USB devices a host controller can handle?

  • 128
  • 155
  • 64
  • 127 

 
What is the maximum number of USB devices a host controller can handle?

EXPLANATION

At 7 bits long, a single USB Host Controller can allow up to 127 (2^7 – 1 Host Controller) connected devices.

USB hubs can be cascaded up to seven times, the maximum number of user devices is reduced by number of hubs. So, with 19 hubs attached, the maximum number of available devices is reduced 127 − 19 = 108.

SOURCE

https://en.wikipedia.org/wiki/USB_hub (Physical Layout section)
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