Sync camera with Bpod

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Sync camera with Bpod
#1
Hi Josh and other Bpod users,

I am trying to sync video acquisition with behavioral tasks using Bpod throughout each trial. The camera I am using can capture frames triggered by individual TTL pulses. The following is my questions: 

1.      What is the best way to trigger the camera and have synced timestamps between the camera and the Bpod? 

           a. use Bpod TTL output channel to send pulses to trigger the camera.       
           b. use Analog Output Module to send a waveform.      
           c. use an external device to send TTL pulses to both the Bpod and the camera. The external device would be  triggered by the onset and offset of each trial. 

2.    If one were to use either the Bpod TTL output channel or the Analog Output module, is it possible to send a continuous TTL pulses within each trial that is dependent on the start and the end of the trial? I could be wrong, but my concern of triggering the camera through each state is that the short delay between states might cause jitters in the frame rate, especially when the frame rate is high. 

Thanks!

Best,
Miao
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#2
Hi Miao,

You can use a Global Timer to control any digital output channel on the state machine (BNC, Wire, Port LED).
In the simplest case, you can have the line go high (5V) when the timer starts, and low (0V) when it ends.
A better setup for your application is to set the timer's "loop" property, and have it toggle the line as in this example.
If you trigger camera frames from the timer channel, you can set the 'Duration' and 'LoopInterval' properties to achieve the desired frame rate.
Otherwise, you can have the camera acquire and timestamp the line's logic transitions on its clock.

I hope this helps!
-Josh
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