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TM4C123FH6PM: TM4C123FH6PM

Sara Sirota
Prodigy 10 points
Part Number: TM4C123FH6PM

We are trying to connect keyboard & mouse via hub to the micro-controller.

We found the USB#01 errata, indicating "USB Host Controller may not be Used to Communicate With a Low-Speed Device When Connected Through a hub".

Is there any way to overcome this issue so that we can work with a low speed  device via a full speed hub?

  • 0
    TI__Guru*** 128255 points

    Hello Sara,

    There is no workaround for that issue. However, low-speed is not really used anyways. Our USB library doesn't even have low-speed support built into it. Only full-speed, which is the standard for many mouse and keyboard interfaces, and high-speed which is the new speed added with USB 2.0 standard. Full-speed is really just USB 1.1 and pretty much every mouse or keyboard in existence uses at least full-speed if not higher nowadays with USB 3.0 and USB-C for the cutting edge devices.

    Best Regards,

    Ralph Jacobi

  • 0 in reply to Ralph Jacobi
    Prodigy 170 points

    unfortunately the TM4C123 does not have a high-speed built-in  (only with external device)  and I will be happy to have USB 3.0 in the TIVA but it doesn't seems to be realistic. 
    we need a product to connect to a wired keyboard and mouse and they are all low-speed. 
    even the standard says that  only LS devices allowed to have a pig tail wire cable.
    that is correct that there are a lots of FS and even HS keyboard and mice, but they are all wireless. all the wired including the new ones are all low-speed.
    further more, with out supporting FS you can't pass the USB certification hence all the TIVA series are not eligible  for the USB certification and it is some thing that you should state to your customers before they use it in there design.
    USB 2.0 should support HS, FS and LS so we cant tell our customer that our product support 2.0 standard not even 1.1. actually there is no standard or certification we can support with the TIVA. 
    I would expect from a big company like TI to fix that bug that is known for at least 7 years.  

  • 0 in reply to gute1
    TI__Guru*** 128255 points

    Hello Gute,

    gute1 said:
    unfortunately the TM4C123 does not have a high-speed built-in  (only with external device) 

    TM4C123x I don't think can support high speed in any situation.

    TM4C129x devices can support USB 2.0 High-speed using an external PHY and we have a TI design with software for that: https://www.ti.com/tool/TIDM-TM4C129USBHS

    gute1 said:
    further more, with out supporting FS you can't pass the USB certification hence all the TIVA series are not eligible  for the USB certification and it is some thing that you should state to your customers before they use it in there design.

    TivaWare supports Full-speed USB by default.

    gute1 said:
    USB 2.0 should support HS, FS and LS so we cant tell our customer that our product support 2.0 standard not even 1.1. actually there is no standard or certification we can support with the TIVA. 

    I am not sure on the specific for what you need, but I can tell you that there is no shortage of customers using TM4C's for USB with USB 2.0 Full-Speed. Maybe their needs are different, but we have not had any complaints from customers failing any certifications using TM4C123x devices for USB.

    gute1 said:
    we need a product to connect to a wired keyboard and mouse and they are all low-speed. 
    even the standard says that  only LS devices allowed to have a pig tail wire cable.

    I have connected to many wired keyboards and mice with TM4C and TivaWare using USB full-speed without issue personally, but I can understand there may be some use cases for it still out there. It is possible to use low speed with the device for sure, but we just don't have that built in because I can think of only three users across over four years that have ever asked for USB low-speed on TM4C versus dozens every month in that stretch who are happy with / specifically want USB full-speed. The need for it has simply been too small for us to invest resources to support USB low-speed.

    Best Regards,

    Ralph Jacobi