I am trying to run a python app which controls sevomotors. There is no handshaking, just a bit bang from pin 3 of the DB9 straight into a PIC.

There is nothing showing on the oscilloscope: it's just flatlining.
I do a dmesg grep | tty and get nothing at all showing.

I've done:
sudo setserial ttyS0 autoconfig
mknod -m 660 /dev/ttyS0 c 4 64 # base address 0x03f8
/sbin/MAKEDEV -v ttyS0
Still nothing shows up on a dmesg

Until I run gtkterm. At which point I can press keys to my hearts content and the scope shows me pretty square waves.
But as soon as I close gtkterm, I've lost ttyS0.

This app apparently works for other people, but that doesn't help me a lot.

I'm running Mint Katya 2.6.38-13 on a Dell Latitude D430, connected to a docking station with a COM1 serial DB9 connector attached, and the BIOS is happy with COM1 active (as proved by gtkterm)

The app is attached as a text file.

So how do I get the computer to permanently see ttyS0, or what would I change in the app so that it will work?
I have python-serial installed, just don't really know what else do.


Anyone got any ideas?

Thank you in anticipation..

Fitch.

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Well, at least you know that the port does work. Sorry but I'm not a Python programmer, so I can't tell you if there is a problem with the code. In any case, you should NOT have needed to create the device node for /dev/ttyS0 - that should by default be auto-configured by the OS for the COM1 port on your system. Do make sure (again) that the COM ports are enabled in the BIOS.

FWIW, I've used a lot of serial ports with a lot of Linux systems, and never saw this sort of problem. :-(

Do make sure (again) that the COM ports are enabled in the BIOS.

No problem.
I can echo directly to the chip just by "echo blah blah > ttyS0", which means ttyS0 is now permanently seen, so the port works fine, just something amiss between Mint and Python.

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