Re: New buffer reading behaviour in continuous acquisition mode?

On Tue, Jan 28, 2003 at 09:01:56PM +0100, Herman Bruyninckx wrote:
> We are using Comedi for analog input with a NI 6024E card, and want to
> get the following acquisition mode:
>  - continuous acquisition at a fixed frequency (1000Hz in our case)
>  - trigger an interrupt each 6 samples (this number "6" must be
>    programmable)
>  - the interrupt writes the 6 samples from the hardware buffer to the
>    Comedi buffer, _overwriting_ everything that still happens to be in
>    that buffer.
> So, what we want to achieve is to always have the six most recent
> samples in the software buffer, always at the same place, _and_ the
> hardware buffer has to be emptied as soon as the 6th sample has been
> reached. (And not when the buffer is half full or so...)

Use a channel list of length==6, with all identical entries, and
enable TRIG_WAKE_EOS.  You may need to turn off DMA on the ni_pcimio
driver to make this work.



dave...

Received on 2003-01-30Z22:59:04