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USB controller on the TM4C123 series

Nomo
Guru 16800 points

Hello,

How many hubs can the USB controller on the TM4C123 series connect?
Also, what the functions work with hardware, and how does the hardware help the software development load.

I apologize to my poor question; however I want to know the feature of TM4C123's USB controller.

Best Regards,

Nomoto

  • 0
    Genius 4680 points

    By the USB spec, you may cascade five or less layers of hubs.
    Each hub layer may have one or more hubs, which connect to hub ports of upper layer.


    http://www.usbmadesimple.co.uk/ums_3.htm

    The total number of hubs and devices on the bus are limited by the 7-bit device address, up to 127 (address 0 serves as  temporary default address on enumeration). Hub also takes one address.

    The cascaded hub layers accumulates propergation delay over hub repeaters / cables. If the last packet from the remotest device would shift over next SOF timing by this delay, babble error occurs. You may set up USBFSEOF register of the Tiva USB host controller, which tunes the gap (guard) between the last transaction and the next SOF on the host bus scheduling.

    Tsuneo