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mvi
Associate III
May 7, 2008
Question

USB Enumeration Failure detection and Inverted USART

  • May 7, 2008
  • 4 replies
  • 651 views
Posted on May 07, 2008 at 07:22

USB Enumeration Failure detection and Inverted USART

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    4 replies

    mvi
    mviAuthor
    Associate III
    May 17, 2011
    Posted on May 17, 2011 at 12:34

    Ummm... No replies still :o

    STOne-32, Lanchon... do you at least have any ideas?

    -Mad D

    mvi
    mviAuthor
    Associate III
    May 17, 2011
    Posted on May 17, 2011 at 12:34

    Hello everyone,

    I got two questions where I require some help.

    1) Is there a way to detect a failed usb enumeration? Think of a situation where 5 units of power is drawn to be drawn on Vbus, for a bus-powered device. Incase the host is unable to provide this, the power drawn has to be downed to 1 unit.

    2) Is it possible to have the USART1 Rx, Tx pins inverted? Think of a logic inverter connected to the Rx and Tx pins. This same thing done in either hardware or software without external components.

    Thank you for your time.

    -Mad D

    mvi
    mviAuthor
    Associate III
    May 17, 2011
    Posted on May 17, 2011 at 12:34

    Thanks for the reply lanchon.

    USART:

    The SIR turned out to work the way I want... But unfortunately, the pulse width in IrDa is 3/16 of the baud!

    I'm now trying to see whether a 10 step PWM signal would work. Unlike bit banging on a GPIO, in a 10 step PWM you can set the next step before hand according to the ST docs. I haven't got this to work yet and dont know how much better/efficient it is. But if someone has worked with it, please let me know.

    USB:

    Mystery indeed!

    -Mad D

    lanchon
    Associate III
    May 17, 2011
    Posted on May 17, 2011 at 12:34

    I'm sorry, I don't know the first thing about USB. I believe that you need to expose two or more different configurations in the descriptors and have the host choose.

    I don't know the USART peripheral. (Of course you could do that by bit banging in GPIO mode.)