50% duty cycle?
Should be no problem for even the cheapest ( sub $10) Aurdino clone.
I wouldn't bother with interrupts for something this simple. Just poll both signals in a tight loop and count the time between when one goes from 0 -> 1 and the other does the same.
But more interesting to me is automating this.
I should mention that I have also been informally discussing this with two other interested parties.
I was thinking of something so small and with no external components required that it was just part of the USB cables.
Maybe an ATtiny ?
QuoteI wouldn't bother with interrupts for something this simple. Just poll both signals in a tight loop and count the time between when one goes from 0 -> 1 and the other does the same.If synchronised. that time would be less than 100 microseconds.
It is extremely simple. In response to momentary press of a button, the controller sets USB to +5V in usual way.When synch is achieved, the controller sets USB to 0V Initially, I will assume drift is negligible for the duration of a typical clip.
please feel free to share those discussions in this forum.
Quote from: waterwingz on 01 / July / 2013, 19:24:11 please feel free to share those discussions in this forum.I mean discussions regarding if they would be willing to produce the device commercially if it works.
The weak point is the mounting of the photo detector, especially on the S95 where the AF led is so near the lens barrel. Today I should receive a faster phototransistor, it is just 2mm x 1mm in size.
In video mode, with SDM, while the USB switch is pressed I now flash the AF led in phase with LiveView period counter.
At 640x480 I get a 30Hz square wave and at 1280x720 I get a 24Hz square wave.I need to make a second photo sensor assembly tomorrow.Now, by half pressing on one camera I could increase the LiveView period slightly at intervals for one cycle and maybe drift the two waveforms into synch.
you seem to have switched from using sync from the video output to actually generating a sync signal?
So does just half pressing move the sync
QuoteSo does just half pressing move the sync Yes.
so all we need is a short script that does click "half_press"
while video is running
Anyway, I have the new phototransistors, have to decide how to mount them so that position is not critical.
Well, I have just finished making some nice housings for the sensors but they are not really commercially suitable, requires some precision manual work.
Fibre optic would not be suitable for same reason.
The new phototransistor gives a very clean, stable waveform, not 50:50 mark-space though.I will investigate if that is a real situation or caused by my code.
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