Weird problem on rs232 vs USB-serial...

Jiri Gaisler jiri at
Tue Feb 24 22:17:27 UTC 2009

The problem might be with your boot loader. We have created many
RTEMS boot images with mkprom/mkprom2 and never seen this problem.
If you use LEON2FT, then you also have to wash all registers
and memory to initialize the BCH checksum, before launching RTEMS ...

mike wrote:
> 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!
> -mike-
> PS:
> - 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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