Re: [ECOS] RE : [ECOS] RE : [ECOS] Serial link problems

[Gary Thomas <gary at mlbassoc dot com>]

Guillaume Menant wrote:
> I've resolved the problem by setting the baudrate to 9600 (a lower one)

Note: as Andrew pointed out, this problem is created by the fact that
RedBoot is a polled driver and your host may be sending characters faster
than it can handle them.  You might be able to get by with a faster speed,
e.g. 19200.

You also might look at how your serial driver handles [polled] timeouts.
RedBoot has a timeout mechanism which is only applied on the first character
of the command line.  If your serial driver's timeout support is poor (in
your HAL - I can't examine it), then this might also cause problems.

> Thanks for your support.
>
> Guillaume MENANT
>
> -----Message d'origine-----
> De : ecos-discuss-owner@ecos.sourceware.org
> [mailto:ecos-discuss-owner@ecos.sourceware.org] De la part de Guillaume
> Menant
> Envoyé : vendredi 12 janvier 2007 09:58
> À : ecos-discuss@sources.redhat.com
> Objet : [ECOS] RE : [ECOS] Serial link problems
>
> Thanks for your answer Gary.
>
> I've understand the same thing but isn't it a driver problem? I'm currently
> working at 38400 bauds no parity, no handshake 8 databits 1 stopbit. Like
> you suggest, I will try at a lower baudrate like 9600 for example.
>
> I will give you some news when I tried this. 
>
> Guillaume MENANT
>
> -----Message d'origine-----
> De : ecos-discuss-owner@ecos.sourceware.org
> [mailto:ecos-discuss-owner@ecos.sourceware.org] De la part de Gary Thomas
> Envoyé : jeudi 11 janvier 2007 12:11
> À : Guillaume Menant
> Cc : ecos-discuss@sources.redhat.com
> Objet : Re: [ECOS] Serial link problems
>
> Guillaume Menant wrote:
> > Hello,
> >
> > While using RedBoot on AT697 (LEON Sparc V8), I've encountered problems
> > using the serial link. It appears that the "_rb_gets_preloaded" function
> > miss few characters arriving on the serial link. For example, I send
> "help"
> > and RedBoot understands "hlp".
> >
> > I've tried to send this command with 2 different softwares: 
> >
> > - The first one send the 4 ascii characters one after the other followed
> by
> > the carriage return -> RedBoot don't understand the command every time.
> > - The second one sends each character as soon as the user hit a key on the
> > keyboard (it's hyperterminal, included in windows XP) -> RedBoot
> understand
> > the command every time.
> >
> > What can I do to resolve this problem? Obviously, it comes from the serial
> > driver included in RedBoot (in io.c), but what kind of modification have I
> > to do to prevent it?
>
> What you're seeing is a serial overflow, caused when characters
> come into RedBoot too quickly.  Your first case, all four characters
> will be sent back to back, in the second, they'll only be sent as
> fast as the person typing them.
>
> Either run at a slower baud rate, or go with the one-character-at-a-time
> style of input.


--
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
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