UART in RTEMS

[Joris van Rantwijk]

On Thursday 12 August 2010 13:14:13 João Rasta wrote:
> No, i have a very low baudrate, 2400. The device is /dev/console_b, as
> instructed in
> 
> http://www.gaisler.com/cms/index.php?option=com_content&task=view&id=82&Itemid=61

I guess then you got your RTEMS distribution from the Gaisler site,
not from rtems.org. The Gaisler version of RTEMS has specific modifications
in the UART driver which are not yet on rtems.org.

For example, the /dev/console driver from gaisler.com supports tcsetattr(),
the version from rtems.org does not.

> After doing some tests i'm now sure that the packets are lost on the
> processor side. The processor is not fast enough to process the application
> and read the incoming packets in time, hence resulting in synchronization
> problems. The receiving sequence is lost because some packets are not
> "grabbed". I wonder if this can be improved by increasing the UART HW
> fifo..?

Increasing the HW fifo should improve at least a little bit.
Using interrupt-based receiving should help even more. The console
driver is probably working in polling mode now.

You could try switching the console driver to interrupt mode
(recompile RTEMS with environment variable CONSOLE_USE_INTERRUPTS=1).
Or use /dev/apbuartN instead of /dev/console_X.
Or try our leonuart driver and /dev/leonuartN instead of /dev/console_X.

Joris.