USB Enumeration Failure detection and Inverted USART

mvi · ‎2008-05-06

Posted on May 07, 2008 at 07:22

mvi · ‎2011-05-17

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 · ‎2011-05-17

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

lanchon · ‎2011-05-17

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.)

mvi · ‎2011-05-17

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