[Elphel-support] External triggering

[Ángel]

Thank you very much, Oleg. I missed the circuit schematics. Now I have only
to make the cable and start with the experiments.

Ángel.

2010/2/2 Oleg Dzhimiev <andersonnotgood at gmail.com>

> Ángel,
>
> J15
> pin 1: GND
> pin 2: camera input, GPIO[10], +5V
> pin 3: camera input, to GND
> pin 4: camera output, GPIO[11], +5V
>
> You can begin with connecting 1-3 & 2-4, setting correct parameters and
> testing with oscilloscope how it works.
>
> The circuit diagram can be found on our wiki - the link is right under the
> 10369 functional diagram.
>
> Oleg
>
>
> On 2 February 2010 14:12, Ángel <elphriend at gmail.com> wrote:
>
>> Thank you very much, Oleg & Andrey.
>>
>> I'm in the process of understanding the camera. Since I have access to a
>> digital sampling oscilloscope I would like to play a little with triggering.
>>
>> So, what pins of J15 must I connect the signal and ground wires of the
>> function generator output to?
>>
>> Thank you, again.
>>
>> Ángel.
>>
>> 2010/2/2 Andrey Filippov <andrey at elphel.com>
>>
>> Ángel,
>>>
>>> Couple more notes about external triggering.
>>>
>>>  This is a "Electronic Rolling Shutter" sensor, so there are some natural
>>> limitations on what you can do with external triggering. If you want just to
>>> synchronize two cameras - it is easy, but you can not trigger the camera
>>> that way from a flash (there are some other ways how to do that). External
>>> trigger on the sensor level work in the following way:
>>> 1 - sensor waits for the trigger to occur, to data and sync signals are
>>> output
>>> 2 - after the trigger sensor skips 8 scan lines (for some internal
>>> reasons)
>>> 3 - sensor _starts_ to erase scan line - one by one - the it will take
>>> about 1/15 seconds to clear the full 5 MPix frame
>>> 4 - after waiting specified exposure time from start of the erasing
>>> process (sensor does not need to wait the full frame to be erased!) sensor
>>> starts readout - line by line, at the same pace the erase process (initiated
>>> at step 3).
>>> The process of readout (and so exposure of the last line in the frame)
>>> will ens in 8*scan_line_time + exposure time + frame_readout_time.
>>>
>>> If you want to catch some instantaneous event (i.e. flash) you'll need to
>>> set exposure time to > frame readout time and initiate that event after the
>>> full frame is erased but before the first line is read out.
>>>
>>> Second note is related to the camera driver - because of pipeline
>>> operation (described in
>>> http://www.linuxfordevices.com/c/a/Linux-For-Devices-Articles/Elphel-camera-under-the-hood-from-Verilog-to-PHP/) it heavily depends on the frame sync pulses from the sensor. So if the
>>> sensor is stopped so is the driver that among others handle all the
>>> parameter changes. If the camera is set to external trigger mode and there
>>> is no trigger coming - the driver will effectively get stuck.
>>>
>>> Andrey
>>>
>>
>>
>>
>> --
>> Elphel NC353L-369 (12-36 VDC) + Computar H2Z0414C-MP
>>
>
>


-- 
Elphel NC353L-369 (12-36 VDC) + Computar H2Z0414C-MP
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