Peter Wurmsdobler wrote:
>
> Hi,
>
>
> 1. Would an ordinary linux kernel be sufficient or do I have
> to use rt-linux in order to guarantee that this periodic task
> can not be interrupted by any other interrupt?
It depends on the sampling frecuency, but in a general purpose operating
systems the interrupts can be bloqued for 10's of milliseconds, so if
you need more than 100 Hz of Sampling freq. you need RT-Linux.
> 2. Even though some drivers for several data aquisistion cards
> are offered at the llp site, I wonder how people cope with
> real time issues using these drivers. As far as I understand
> rtl (thanks to Tomek), a conventional driver cannot be accessed
> within a rt-module, unless this code is integrated in itself.
You have to take the code of the driver and adapt it to RT-Linux. I do
it for a DAS1400 and was relatively easy.
> 3. If the real time module controls the data aquisition
> card entirely, how can I pass configuration information to
> it from a user programm, like start conversion, set sampling
> frequency etc.?
Whith RT-fifos. You can use one for commands and another to get data.
> 4. Is it reasonable to make an own module exporting some
> hardware related functions e.g. rt_read_DAC0 for the
> data aquisition board in addition to a real time module
> (not necessarily a process) and the fifo module? Who will
> register the interrupt of the board then? How will they
> work together?
I use only one module (but the card driver routines are of course in a
separate file)
> 5. Is it even necessary to use rt_sched, if I had only one
> periodic task? My common sense would say no. Insert just one
> module in a real time kernel in order to not being interruptible
> would do the job if timing is done by the card itself?
Yes, The rt_sched is the responsible to gives the time not used by the
RT-Modules to the Linux kernel.
Regards
Dani.
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For more information on Real-Time Linux see:
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