Shorting C1 Ground and timemark pins using led light


I am using a parrot sequoia camera and want to do ppk using reach m2.

The x-sync and ground of a camera is used to fire up a flash. The hot shoe detects the closing of the circuit which then shorts the C1 ground and timemark pins on the m2 creating an event marker.

I am thinking of using a led circuit to detect when the indicator light of the camera fires up and use the lightning up of the led bulb as a way to close the circuit of the m2. I am concerned though that the voltage flow as a result of a led lightning up will damage the M2 (unlike in the hotshoe where the current from the flash is the one flowing back to the flash).

So, will the 5v or so flowing through the led then through the C1 ground and timemark pins damage the M2? I have very limited knowledge on electronic circuit so will gladly stand corrected.


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Hi @rogerix20002000,

Wow, interesting setup! Sadly, there is no hot-shoe access in this camera.

Here is the thing.
Time Mark pin is open drain. You need to switch it to the ground to record a time mark. The maximum voltage for the time mark pin is 3.3V. The pin is not protected from higher values, so you will most likely toast this pin with 5V.

I can recommend using GCPs if this solution works for you.


Thanks for pointing out the 3.3V maximum voltage! That save me from frying my M2.

If I want to see how the time mark works I can just follow the general illustration I made below, make sure satellites are properly communicating with the M2 and I should see the dip in signal in reachview, right?

As you pointed out maximum of 3.3v, what could be the least voltage that will trigger the time mark?


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No problem! :slight_smile:

The voltage should always be 3.3V on the Time mark pin.

HI! Thanks for the reply.

Re: 3.3v timemark pin will a 3.6v fry the pin?



Yes, it will. The only possible voltage on the Time mark pin is 3.3V.

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