rt_com and serial break

Rudolf Seemann kapitaen at gmx.at
Sat Aug 10 11:25:56 CEST 2002

Shame on me.
Well, I should have read the UART8150 specification before posting this
For anyone interested in sending serial line breaks. Here is the simple
command which generate this signal out of a kernel module:
outb(0x40,0x3FB); // com1
outb(0x40,0x2FB); // com2
These lines set the 6th bit in the LWR-register. In consequence the uart
generates a serial line break which is something similar to a series of
null bits but in contrast to a normal character this signal lasts 0.25
to 0.5 seconds on the serial port.

> Hey out there!
> I am trying to set up a real-time module reading and writing to the
> serial port in a real-time scheduled task. For this purpose I set up
> rtai-24.1.9 and linux-2.4.18. I grepped the rt_com sources distributed
> with the rtai-package and could not find any serial_break function.
> Did anyone implement such a function?
> Thanks in advance
> Rudi
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