[Elphel-support] External triggering

[Oleg Dzhimiev]

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
>
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