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Occasionally GET_PICTURE ACKs but does not send Data

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  • Occasionally GET_PICTURE ACKs but does not send Data

    Generally, uCAM-II has been very easy to work with, but there's one intermittent issue that I can't figure out. Periodically, uCAM replies with an ACK in response to a GET_PICTURE (AA 04), but never follows on with sending a Data (AA 0A) message. After that I'm unable to communicate with the camera at all - until a power cycle. This happens may take 1-10 minutes of reading images every 1-2 seconds (160x120 RAW).

    All communication signals look great - timing, levels, edges.

    Any ideas on how to avoid this?

    Is there anyway to recover (other than a power cycle)?

  • #2
    One more detail. I usually use 921600 baud, but have tried other rates down to 115200. I still see the same issue.

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    • #3
      I set the demo software to 115200 and RAW 160x120.

      I then checked 'Video mode' (which is simply another 'get picture' as soon as the current one is finished) and Started it by clicking the first 'get picture'.

      It's now 15 mins since it started and it's still running.

      Can you try that with yours?
      Mark

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      • #4
        Hello,

        I'm having the same issue with the U-Cam ii. I'm using a 115200 Baud rate, and RAW grayscale image type with 128x128 resolution.
        After receiving the ACK (AA0E04) in response to a Get Picture (AA0402), the camera sends nothing, not even a NACK. The only way to restore functionality is a power cycle.

        Sometimes, this happens around 10-15 times a minute, making performance very choppy. But it's very unpredictable, as I get minutes at a time without any issues. Is there a way to resolve this problem?

        Thank you

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        • #5
          How much 'wire' exists between the camera and the host, and how is it 'shielded'?

          We have never seen this, so we can't comment on whether full and/or special reset might solve it.

          Also check this post, as maybe it can cause the issue? http://forum.4dsystems.com.au/forum/...hermal-problem
          Mark

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          • #6
            Hello,

            The total length of wire between the Camera and host is around 12 inches. It's shielded by an aluminum spiral serve. I've attached the shield on the Host end to ground.

            Below, I've attached an image of the wire end at the PCB and at the Camera. I'm running my code via LabVIEW 2016, using an ELVIS II platform with an ELVIS RIO Control Module, all of which are required to be able to run my code, which is why I haven't attached it. I'm running the loop as fast as possible in VIDEO mode, as stated in my post above. I'm following the U-CAM II specifications very closely, and can confirm that the ACK command (AA0E04) is being received after sending a GET PICTURE (AA0402), but the camera sends nothing after that. After waiting for 35 cycles of my loop, I power cycle it, resync and reconfigure, after which performance resumes.

            In general, I do receive pictures correctly for chunks of time, telling me that my code works correctly. But the issue where it sends no image data, occurs anywhere from once every 5 minutes, to 12 times a minute.

            Click image for larger version

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            Last edited by MBohra; 30th August 2016, 06:33 AM. Reason: grammar

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            • #7
              It really looks to be some sort of noise / interference issue. If you have 'the rest' of the equipment powered down does it run longer?
              Mark

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