How to keep camera from leaving rec mode when PTP drops? - page 2 - General Discussion and Assistance - CHDK Forum
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How to keep camera from leaving rec mode when PTP drops?

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Offline reyalp

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Re: How to keep camera from leaving rec mode when PTP drops?
« Reply #10 on: 02 / March / 2017, 02:01:33 »
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Does this typically mean that the input voltage is low?
Typically, yes. It wouldn't be totally surprising if the battery temperature signal could trigger a similar shutdown though.

Quote
These cameras are powered off a fixed power supply in this installation. Should be right at 4.2v.
Monitoring that seems like a good idea. You could log in CHDK, but if you can track it externally that might be better.
Don't forget what the H stands for.

Re: How to keep camera from leaving rec mode when PTP drops?
« Reply #11 on: 06 / March / 2017, 18:50:44 »
Still chasing this one. I have tried adding a great deal of filter caps onto the power lines (100uF) as well as bumping the voltage to 4.6v. Based on my testing with an adjustable power supply it has to drop below 3.2v before the "Change the battery pack" message appears, which I think is pretty unlikely.


So I'm pretty stumped on this. Maybe this is some side effect from triggering through the third battery terminal?

Re: How to keep camera from leaving rec mode when PTP drops?
« Reply #12 on: 06 / March / 2017, 19:26:43 »
Maybe this is some side effect from triggering through the third battery terminal?
That might very well be a possibility.

The third terminal contact expects to see a local resistive temperature sensor housed in the body of the battery.  So it's quite possible there is little or no filtering inside the camera.  Any external wire hooked up to this terminal is a great antenna if not adequately shielded and single point grounded. 

The usual solution is decoupling caps (a few microfarads) between the third terminal and the ground contact as close as possible to the terminals themselves (i.e. inside your dummy battery / battery compartment).

Edit :  an even better solution would be an optocoupler at each camera - drive the input anyway you can - isolate the output to the camera and connect via really short wires
« Last Edit: 06 / March / 2017, 21:25:39 by waterwingz »
Ported :   A1200    SD940   G10    Powershot N    G16

Re: How to keep camera from leaving rec mode when PTP drops?
« Reply #13 on: 07 / March / 2017, 16:43:54 »
In classic personal fashion as soon as I posted that I had given up to the internet I solved the problem almost immediately.


Basically if the trigger line is connected to ground and goes below about .2v, the camera shuts down with this message. It only does this once the trigger is "active" though. If you power it up with the trigger at ground it will not shutdown, but once it goes above ground it subsequently can't go below .2v or the camera shuts down.


So my fix was to add some small pullup resistors to make sure it is always around .4v when in the "low" state. Still testing this but so far so good!




James


 

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