Re: Advice Needed

[Fraser Farrell <fraser@trilobytes.com.au>]

Tom Droege wrote:
>
> 2) I want to install a cheap webcam on this machine.  I want one that will
> just work, otherwise it will be easier to use Windows.  Since cameras are
> so cheap, I am quite willing to buy one that is known to work.  This seems
> to be the easiest approach to using something on linux.

See www.gphoto.org for the list of ~300 digital cameras and webcams that are 
supported by gPhoto. In general any new camera with a USB outlet will work, 
including "live video" modes. Alternatively I have discovered that many cheap 
generic webcams will work okay with xmovie too. I guess the cheap ones all 
use the same (one or two) chipsets?

gPhoto and xmovie are included with most modern Linux distributions. Possibly 
on a supplementary programs disc.


>
> 3) I want to run a simple program on the linux machine which sends
> characters out on the serial port.  Best if I can do this in a  perl
> program.

Might also be done by sending the "standard output" to the serial port. A 
trick which works in DOS too, incidentally. Imagine you have a program or 
script called "domecontrol" which prints the A a B b 's to the screen. You 
could then run it like this:

  domecontrol left shut  >  /dev/ttyS0

to send the characters to the first serial port (in RedHat) to shut the left 
side of your dome. I reckon this could be done with a shell script.

As for timing the operation....personally I would avoid using the Linux 
"date" command. I suspect that "date" was created by someone on happy weed. 

If you're going to write this as a shell script then try using a "sleep 1" 
between each character send. I'm assuming it doesn't matter if it takes 10 
seconds to transmit 10 specific characters to your dome motors?


>
> DOS has a seconds since
> midnight, does linux have a similar time command?

Linux counts seconds since the Beginning Of The Unix Era - 1970 Jan 1 00:00 
UTC. We're up to about 1.05 billion seconds now. I understand there's going 
to be an arithmetic overflow on this counter sometime in 2038, but even I 
will have upgraded by then :-)


>
> 4) I want to be able to sit in my office elsewhere on the ethernet and open
> a window that shows what the camera sees. 

That would be an X terminal on your office computer, linked to an X server on 
the dome computer. Or you might try a VNC server/client combination. I use 
the latter to administer some Windows NT & 2000 servers remotely from my 
Linux box at home.

>
> Then I want to open a terminal
> and run the program to open and close the dome.

If your network is isolated, telnet will suffice. Or for much better security 
use OpenSSH.

I'll leave it to the Linux gurus to come up with better suggestions than 
these.



cheers,

-- 

Fraser Farrell

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