How to align Chameleon 3 TTLs with Matlab recording

Answered

Nicholas Timme

• August 30, 2024 14:57

Hello

I have a chameleon 3 camera that I am running via Matlab. I have figured out how to successfully start image recording from Matlab, but I would like to be able to record the precise time of the frame grabs so I can synchronize the video with other events being recorded in Matlab.

I have figured out how to turn on frame grab TTLs via the GPIO pins by modifying the camera settings in FlyCapture2. I can see the TTLs and simultaneously record them in Matlab. However, the TTLs are constantly being produced by the camera, even before I start recording video. In other words, I start receiving the TTLs in Matlab prior to initiating the video recording.

Is there a way to figure out which TTLs correspond to the recorded frames? Alternatively, is there a way in to turn on the GPIO outputs only when recording or some alternative method for obtaining the time of each frame grab via Matlab?

I would appreciate any information anyone can provide about how to solve this problem. I've looked around online and I haven't been able to find a solution to this problem. If I missed it, I apologize and I would appreciate it if someone would point me to the correct resource. Thank you!

~Nick

0

• Official comment

  

  TDY_William

  Community team

  • September 05, 2024 17:46

  

  

  Hi Nicholas,

  Strobe output (what you refer to as TTLs) occurs whenever the camera captures an image; it doesn't change if the camera is recording or not.  However, one method we use in FlyCapture2 is to have the camera with trigger mode turned on, then turn on recording; with no triggers being issued, no images are being captured.  Once recording has been setup and enabled, we then turn trigger mode off, and the camera will start capturing images; this way, you can be guaranteed that the camera is only sending out strobes that are occurring when recording has already started.  I would recommend seeing if you can do something similar in Matlab.

  If that is not an option, then a different option would be to externally trigger the camera using an external hardware trigger device, and not send external triggers to the camera until recording has been setup and enabled.

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