serial port weird chars ...

[Antony Pavlov]

On Fri, 07 Aug 2015 15:03:52 -0400
Roberto Alejandro Espi Munoz <raespi at icid.cu> wrote:

> Both scenarios work well on another host.  On my host serial port when 
> interacting with one bootloader the communication is fine and with 
> barebox fails.  When using a USB-serial adapter there's no problem.   
> Perhaps there's a problem on my board but why does the first connection 
> work and with barebox doesn't ?

May be barebox programs UART clocks in a slightly different way than S3C2440A USB Downloader does,
so waveform for one character is too short or too long for your host computer UART receiver?

IMHO a logic analyzer can help you. Use it to compare output mini2440 UART waveform from USB Downloader
with output UART waveform from barebox.

> 
> On 08/07/2015 12:41 PM, Antony Pavlov wrote:
> > On Fri, 07 Aug 2015 10:41:12 -0400
> > Roberto Alejandro Espi Munoz <raespi at icid.cu> wrote:
> >
> >> Hi ... I'm currently having some trouble with displaying characters
> >> correctly in my terminal.  I'm using a board equivalent to the
> >> mini2440.  This one has a NOR and a NAND.  I connect to it over a serial
> >> port interface.  When I boot up the board in debug mode I'm able to see
> >> clearly the messages displayed by the S3C2440A USB Downloader which is
> >> copied in the NOR interface, I then download my barebox binary over the
> >> USB interface and when it boots I get a lot of weird characters on
> >> screen.  The console seems to respond correctly, I issue for example the
> >> "reset" command and it resets but I can't make out what is displayed.
> >> I was guessing at first a serial port configuration problem on my
> >> operating system (I use Linux), tried it over on Windows and same
> >> effect, the first bootloader works great and barebox when starting just
> >> mangles the characters.
> >>
> >> The other weird problem is than when I use a USB-Serial converter to
> >> connect to the board's serial port everything works !
> >>
> >> I'm currently using barebox 2012.09 and OpenSuse Linux 13.2
> >>
> >> Any ideas ? thanks
> > You have the problem if you use your host computer motherboard serial port (no matter, Linux or Windows),
> > isn't it?
> > And no problem if you use USB-Serial dongle. So it looks like host serial port problem.
> >
> > Could you try to connect the board to another host computer?
> >
> > -- 
> > Best regards,
> >    Antony Pavlov
> >
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> 
> 
> 
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-- 
-- 
Best regards,
  Antony Pavlov