Weird problem on rs232 vs USB-serial...

mike antispam21 at
Tue Feb 24 18:43:39 UTC 2009

Thanks Jiri,

1) with grmon, everything was fine. The target DSU was connect on ttyS0 
and Uart on ttyS1.
   We always used 'grmon -freq 66 -leon2', and it connected fine. 'load 
xxx' then 'run' was fine as
   I could see the RTEMS shell coming up on ttyS1 (with minicom connected to
   ttyS1, 38400, 8N1 and no flow control). The target has a basic 
bootrom but
   we were not using it in this case. The exe file was an executable 
linked and
   resolved to 0x41000000 (for our purpose).

2) Now, when we were not using grmon, on power up the target, the bootrom
    messages came up on ttyS1 as expected. We then loaded the same RTEMS app
    to ram at 0x41000000 with the bootrom ( and with minicom raw 
upload), with a binary
   file produced from .exe in (1)  above by sparc-rtems-objcopy -O binary,
  then jump to 0x41000000. Nothing  on ttyS1

3) the funny thing is, with the target uart port connected to 
usb<->serial, repeating
    (2) above worked as expected (RTEMS shell came up on ttyUSB0, with
   minicom connected to ttyUSB0, same 38400, 8N1, no flow control.

Anything else I can look? Thanks!


- the bootrom set the target uart to 38400, no flow control ,  8N1
- I set it (0x80000078 & 7c, UART control/scaler) again in the RTEMS 
app, just to test. No change.
- I use shell.c in the RTEMS tree. I also set B38400 there. No change.

Jiri Gaisler wrote:
> If you load your application via grmon, check that the
> detected target frequency is correct. Grmon will use
> this frequency to set the baud rate of the UARTs.
> If the frequency is wrong, the baud rate will be
> set wrong and your host UART will not receive the
> characters. Try to use the -freq XX option when starting
> grmon to specify the target system frequency.
> Jiri.

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