StereoPI V2 - how to trigger a flash light?

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mr.burns
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Joined: Fri Mar 19, 2021 5:16 pm

StereoPI V2 - how to trigger a flash light?

Post by mr.burns »

Hi,

I ordered StereoPI V2, and I want to be well prepared if shipment arrives ;-).

Since I want to use the StereoPI V2 only for still images I need a flash for low light situations.
Is there any way to trigger a flash?

Typical flash shoes have one middle contact which is to pull to ground to trigger the flash. Can I do that with an GPIO of StereoPI V2?
Since it is necessary that flash fires if both cams have shutter open the timing is key. Can the flash trigger timepoint be adjusted by software?

Thanks...

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Realizator
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Re: StereoPI V2 - how to trigger a flash light?

Post by Realizator »

Hey Mr. Burns,
Hmmm, I found that the flash driver is enabled in the Raspberry OS kernel for a long time (related Raspberry forum thread, stereoscopy-related).
So the only thing we need to do is to assign a pin for the flash support in our dt-blob.bin, and it should work out of the box. We should think of how to avoid the pin functions conflict in this case. Maybe we'll create a special dt-blob.bin to use for the flash function.
Eugene a.k.a. Realizator

stereomaton
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Joined: Tue May 21, 2019 12:33 pm
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Re: StereoPI V2 - how to trigger a flash light?

Post by stereomaton »

You probably want to add electronics between the GPIO and the flash. Depending on the schematics I found online, they add either optocoupler (that I would personally prefer as it isolates the two sides), transistor, thyristor or even sometimes triac. You might add an ne555 to add an adjustable delay if you want.

To enable it in the kernel, realizator, maybe a device tree overlay would be more pertinent than a new custom dt-blob.bin
Stereophotographer and hacker
Despite my quite active participation in the forum, I am not in the StereoPi team
StereoPi (v1) Standard Edition + CM3Lite module + a few cameras

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