Hi Alexis, I was wondering whether you could help me with some information about CMD based data acquisition in analogy. You might recall from previous emails with you, we are trying to implement high speed data DIO communication with a NI6259 board. We use the CMD structure to create a periodic task, that is clocked by a timer, to achieve the required communication speed. As we need to change the R/W polarity on some channels every 20-30 scans, we need essentially to find out when the data in the communication buffer are consumed, such that we change polarity and trigger the next set of acquisitions. Currently, working with the MMAP options seems to be the best way of handling this.
I just had some questions concerning how to detect when the data are consumed. It appears that the periodic task is automatically canceled when a "DMA underun" is discovered (as can be checked with dmesg). Is this automatic canceling behavior the officially correct behavior? I can use a4l_poll to find out how much data is left in the communication buffer --- I noticed that it returns -EPIPE when the data buffer has been consumed, which also seems to indicate that the periodic task has been canceled. (So for, the -EPIPE return code is not documented in Analogy). I am running your latest Analogy branch. I was just wondering whether my observations are correct, and that it makes sense to develop more communication code by using this behavior of Analogy. Best wishes, and Happy Holidays! -Stefan _______________________________________________ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
