[GreenKeys] USB to TTY-loop possibility...

[epvgk at limpoc.com]

On Fri, Nov 02, 2012 at 03:37:03PM -0500, Jim Haynes wrote:
> On Fri, 2 Nov 2012, epvgk at limpoc.com wrote:
> 
> >It has an internal UART which *can* generate the right framing, except that
> >in order for USB to work you have to clock it high enough that the UART won't
> >run at TTY speeds. I actually generate the characters (and decode, for that
> >matter) with a state machine in an interrupt routine that can be clocked
> >anywhere from 0.24 baud to hundreds of Kbaud.
> >
> OK.  I think someone mentioned a particular make of USB to COM port
> adapter that would actually run at TTY speeds, which most of them
> will not.

Yeah, it's the dev model of a CP2102 board that hasn't had its config
locked yet, I think. You can program the clock divisor for certain requested
speeds such that they work out to be 45, 56, 75 or whatever baud. But you
still have to send it baudot, and it still has a buffer, so it might be 
more convenient to have something do it all for you.