[Soekris] COM2 Problem with OpenBSD4.3 on NET4501

[Stuart Henderson]

On 2008-07-23, grice at iastate.edu <grice at iastate.edu> wrote:
> OpenBSD 4.3 installed smoothly, but I’ve been wrestling with serial 
> communication over COM2 for days now.  At the moment I have a simple C program 
> designed to echo any data sent to the serial port to stdout.  I’ve tested the 
> program on other OpenBSD 4.3 PCs without issue, but when I move the code to 
> the Soekris board, I see data being received, but it’s entirely corrupted.  At 
> this point I have tried sending the data at multiple baud rates, both with and 
> without CTS/RTS.  The results are always the same.  I receive data as it’s 
> being sent, but it’s not the data I expect.

Your program is probably ok, but you could isolate it by using a known-
good program like cu.

# cu -l -s <speed> /dev/cua01

> The code for the echo program is listed below.  Must CTS/RTS be connected?

No, you aren't using modem control lines, so RXD/TXD/GND is enough.

> noticed in another message thread, 19200 is the recommended baud rate for 
> COM2.  Is this true?  If so, why?  Must I use 19200?

No, you can use any speed supported by the port.

> Any other recommendations?

Check things are wired correctly. The pinout is given in the board's
manual, http://www.soekris.com/manuals/net4501_manual.pdf, also see
http://wiki.soekris.info/Serial_port. Some PCs use this layout, others
don't. If you use an IDC DE9 connector the ribbon cable should be
crimped on flat, not split and reorganised.