Hot-shoe signal to external GPS

Started Apr 24, 2017 | Questions thread
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DPR_gio New Member • Posts: 3
Hot-shoe signal to external GPS


I'm new to this forum, and hopefully this is the right place to post this question; I'll post the question on the UAV photography section, as it can relate very well there as well.

I also tried to contact Max (, as he seems to have a great deal of knowledge on hot-shoe inner workings, but had no luck.

Anyways, this is the scenario:

I have a Nikon D3300, and I have connected, thorough a specific accessory (, the hot-shoe 'signal' to the 'external-event' time-mark pin of an Ublox M8T GPS receiver: this way, every time I shoot a picture the shutter activation, through the above hot-shoe circuit, sends a signal to the GPS which then records the precise time when the image was taken.

The hot shoe adapter is supplied by (a 3.7 V Li-Po battery connected to) a 3.3 V regulator, and hardware-wise things seem to work: the issue I'm facing though is that not all the 'shutter activation pulses' are detected and logged consistently by the GPS unit, and I suspect this depends on the hot-shoe signal duration (being too short at times...?? not sure) - the GPS time mark pin operates at TTL level, can detect falling or rising edge pulses, and it's fairly flexible and reliable.

I'm writing hoping someone with hot-shoe knowledge can help: I do not really know the hot shoe signal in terms of pulse duration, and its dependency on other camera parameters/settings (such as shutter speed, internal/external flash, etc), and if anything can be done to increase the duration of the hot shoe pulse.

Thanks in advance for reading this, and for any feedback you're willing to provide.

Best Regards


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Nikon D3300
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