2011/10/5 Fernando Herrero Carrón <[email protected]>: > > > 2011/10/5 Gilles Chanteperdrix <[email protected]> >> >> On 10/05/2011 09:48 AM, Julien Delange wrote: >> > On Tue, Oct 4, 2011 at 12:41 PM, Gilles Chanteperdrix >> > <[email protected]> wrote: >> >> Another mail in that thread seem to suggest that it could be long. Have >> >> you tried timing the various parts of your loop to see where the time >> >> is >> >> spent? >> > >> > No, sorry, my bad. Unfortunately, I cannot make more tests at this >> > time because I don't have the hardware. >> > I will do additional investigation soon, I would have access to the >> > acquisition card soon. My intent was to know if there was an obvious >> > error either in my code or in my kernel configuration. Apparently not, >> > so, I will try to figure out the root causes of these issues. >> >> It is my understaning when reading Fernando's answer to your mail that >> you are not using the proper interface for what you are trying to do. >> > > Yes, my suggestion is to use a different interface that will definitely > provide higher acquisition speeds. However I am wondering if using the > "instruction" interface the delay would be over the milliseconds. I'm > recalling some tests that I did using comedi in linux user-space, that is > without any real-time support software. I could acquire 8 channels and the > board's internal timer using the instruction list technique at 120us > (microseconds) intervals. However my board has 8 parallel ADCs (NI 6143), so > check if yours has parallel or serial converters. If it has to serialize > conversions then the overall acquisition period will increase. > > Back to your code, are you sure about "insn_tab[i].data_size = 8;"? Try > data_size = 1 instead. >
The field data_size is supposed to hold the size of the acquisition in bytes. If you have an 8bits converter, 1 is OK; but according to the driver Julien contributed, the converter width is 16bits. > Best, > Fernando > > _______________________________________________ > Xenomai-help mailing list > [email protected] > https://mail.gna.org/listinfo/xenomai-help > > Alexis. _______________________________________________ Xenomai-help mailing list [email protected] https://mail.gna.org/listinfo/xenomai-help
