[SOLVED] Continuous data sampling

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  • [SOLVED] Continuous data sampling

    Hi, is it possible to sample data continuously with Ozone (3.26h)?

    Right now, I get approx. 31 ms data, 13ms no data, 31ms data, 13ms no data and so on.
    Debugger is J-Link Ultra+, Sampling rate doesn’t change this behavior. It works with J-Scope, but that is no alternative, because it can’t find my variables.

  • Hello,

    Thank you for your inquiry.
    Maximum data sampling frequency depends on the debug probe you are using.
    Which one are you using? What is its serial number?

    What is the expressions you are sampling? Could you provide a screenshot of your setup?

    Best regards,
    Nino
    Please read the forum rules before posting.

    Keep in mind, this is *not* a support forum.
    Our engineers will try to answer your questions between their projects if possible but this can be delayed by longer periods of time.
    Should you be entitled to support you can contact us via our support system: segger.com/ticket/
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  • I was sampling a global float variable. As I said, I am using a J-Link Ultra+ and it is not a problem with the sampling rate. It happened at 100Hz too. I cannot replicate this behaviour at the moment. It is more or less continuous right now, but there are still some missing samples every millisecond or so.



    So, my question is more general. Should it be possible to continuously sample data, without holes or is this* typical behaviour because of buffering or something else like RTT?
    * with this I now mean what we see in the screenshot, the 13ms of missing data is obviously not normal.
    Images

    • sampling.PNG

      17.63 kB, 1,093×245, viewed 198 times

  • Hello,

    Which J-Link Ultra+ exactly? There are multiple hardware revisions. Could you share your serial number please?
    What target device are you debugging exactly?

    Continuous recording is possible. However there will be naturally gaps as the gaps are defined by your sampling frequency. You have set it to Max which is >10 kHz. But e.g. if you set it to 100 Hz it is expected that between each sampling point there is a delay of ~10 ms (for 10 kHz it would be 0.1 ms). There is some delta here as J-Link will try to match the sampling frequency as accurately as possible but sometimes the background task might get blocked more depending on the workload so the delay may be a bit higher for some data points.

    But that is no bug. This is simply how sampling of any data works. The same is on your oscilloscope. It is all dependent of the sampling frequency.

    Best regards,
    Nino
    Please read the forum rules before posting.

    Keep in mind, this is *not* a support forum.
    Our engineers will try to answer your questions between their projects if possible but this can be delayed by longer periods of time.
    Should you be entitled to support you can contact us via our support system: segger.com/ticket/
    Or you can contact us via e-mail.

  • V4.3 and the target is XMC4400-512.

    I'm aware the there are no sample points in between sample points … this is not what I was asking about.

    SEGGER - Nino wrote:

    but sometimes the background task might get blocked more depending on the workload so the delay may be a bit higher for some data points.
    Hm, that could be the case in the screenshot (if by "sometimes" you mean every 1ms or so and by "higher delay" you mean missing)