Hi Alexis,
amazing progress!! And it works! I just ran my test program on our NI6259
board and got perfect performance. I quickly tested 5MHz DIO rate, and it
appeared to work fine according to the square waves on the oscilloscope.
I will go back to developing our DAQ interface, and report back to the
Xenomai list about performance.
Thanks so much
Best wishes,
-Stefan
On Aug 23, 2010, at 16:09, Alexis Berlemont wrote:
Hi,
Stefan Schaal wrote:
Hi Alexis,
as usually, we are more than grateful that you are willing to spend time on
this issue. Here are answers to your questions:
1) I tried CR_INVERT -- no success
2) I tried very slow frequencies like 10Hz in the counter clock (which is
nicely visualized on my oscilloscope) -- no success
3) I tried to send a 0 with cmd_bits -- and interestingly, this ALSO takes
my DIO line high (sorry, I thought I had tested this before). This would
indicate that we do not access the FIFO at all?
4) I have my own test program to send alternating 0x and 0x0 values
to the devices to generate a square wave on the oscilloscope. I cannot see
anything of the square wave executed.
At last, it comes!!!
Thanks to your test program and your help, I think I have fixed this
bug. Could you clone my git repository (branch analogy), and give it a
try with your own test program.
There was a bug in the mite configuration which explained why the
wrong data were sent to the DIO subdevice. That was also the reason
why no interrupt came from the mite.
Best wishes,
-Stefan
On Jul 19, 2010, at 15:01, Alexis Berlemont wrote:
Hi,
Sorry for answering late.
Stefan Schaal wrote:
Hi Alexis,
I managed to port some of the Comedi examples to Analogy. In particular, I
could configure one of my counter subdevices to become a high frequency
clock, following the gpct_pulse_generator.c example. I routed the output
of the clock to my PFI0 pin, and could visualize the signal on an
oscilloscope. Thus, I know have the clock I need to trigger CMD-based DIO,
as you suggested. (I will post some sample code of this in the near future
after all is cleaned up).
Next, I went back to cmd_bits.c and try to make it work on my NI6259
board. For scan_begin_src=TRIG_EXT I need to choose scan_begin_arg = 28
(which is kCDO_Update_Source_SelectG0_Out in the NI documentation, and
NI_CDIO_SCAN_BEGIN_SRC_G0_OUT in the comedi.h file).
When running cmd_bits.c in this way and monitoring the DO channels on an
oscilloscope, the DO switches to HIGH when the acquisition is triggered
(i.e., the value of the first element in the FIFO), but the FIFO is not
processed any further, i.e., not emptied. If I DO NOT run the
counter-clock above, the DO does not even switch to HIGH. I also checked
whether 28 is the right value for scan_begin_arg by trying a wide range of
values, but only for scan_begin_arg = 28 I get the DO bit switched to HIGH
at the beginning of the acquisition.
In Comedi, the cmd.flags is set to CMDF_WRITE for such externally
triggered acquisitions, which I tried, but it did not help.
Thus, it appears that I still have a problem in processing the FIFO,
despite it appears that all other things are now correctly connected
(Comedi has an example do_waveform.c, which is pretty much what I try to
use for testing in my own code).
Would you have any thoughts on what might go wrong? It looks like we are
just a tiny bit away from succeeding with cmd_bits.c on my board.
I had time to have a look at your problem. Unfortunately, I do not
have any solution. I just have some questions you may find stupid:
- Did you try to invert the sample clock polarity by setting the flag
CR_INVERT in the command field scan_begin_arg?
- Which frequencies did you generate with the counter subdevice? Even
the lowest one did nothing (Something like 10Hz)?
- Did you try to send 0 with cmd_bits ? Just to check that the DO stay
to LOW, which would mean that the values (or at least the first one)
are properly loaded into the device.
- So far, cmd_bits always sends the same value (the one you passed as
argument); we should modify it so that the complement value is
written every two samples. That would allow us to physically check
how many samples are played by the DO.
Best wishes,
-Stefan
On Jul 14, 2010, at 17:46, Stefan Schaal wrote:
Hi Alexis,
in the Comedi examples
(http://www.comedi.org/download/comedilib-0.8.1.tar.gz, the do_waveform.c
example), they suggest to use a general purpose counter as clocking input
to a cmd-based DIO acquisition. This seems to be the signal
kCDO_Update_Source_SelectG0_Out= 28 from the enum you found
in the NI documentation.
For this purpose, the counter needs to be configured and triggered. Does
Analogy already have the functionality to do such operations? The Comedi
libraries have an example for this, too, in
