Re: Re: RTAI and Comedi: Problems with commands

Hi everybody 

I have scanned through all the comedi sources and I have one question concerning
the issue I have asked before:
When I understand the command things right, the analog in data is transferred via DMA
to the async->prealloc_buf. 
I found out that the data will be written to prealloc_buf.
My question is now: Where in the comedi code is the data transferred from prealloc_buf to the 
user address space?
In "standard" (non realtime) comedi this is happens in comedi_fops.c (function comedi_read).
I have not found a corresponding code that can do this for RTAI LXRT.

Thanks a lot

Mathias
> 
> On Monday 06 November 2006 13:14, M. Koehrer wrote:
> > Hi everybody,
> >
> > I am trying to use the comedi commands using RTAI (RTAI 3.3CV, latest
> > comedi/comedilib). On the RTAI CVS I have found an (old?) example testa.c
> > that I used as base. (see attached testa.c).
> > The program testa sets up a command to sample from the first AIN channel
> > a couple of times.
> > The test compiles and runs (10 lines are printed out), however the data
> > value is always 0.
> > I have debugged into the driver (I use a simple PCI NI 6024-E) and I
> found
> > out that the data is transferred correctly via DMA to the async
> > prealloc_buf. It seams as the only thing that misses is the transfer from
> > the internal (kernel space) memory that holds the input values (written
> by
> > DMA) to the user space value.
> >
> > One strange thing that I have detected was the following:
> > The function rt_comedi_alloc_cmd() sets internally the values of
> cmd->data
> > and cmd->chanlist and returns the values in the arguments **chanlist and
> > **data. However, when testa returns from comedi_command_test() the value
> of
> > cmd->data has changed - it points now somewhere in a 0xexxxxxxx address
> > space. Could this be an issue?
> >
> > Is there somewhere a running example available that shows working comedi
> > commands with RTAI?
> >
> > Thanks for any help on this issue.
> >
> > Mathias
> 
> -- 


-- 
Mathias Koehrer
mathias_koehrer_at_arcor.de


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Received on 2006-11-06Z16:04:05