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Power Cycle Issue — Parallax Forums

Power Cycle Issue

lpettipalpettipa Posts: 2
edited 2012-07-16 07:39 in BASIC Stamp
HI, I'm very new to this forums, and have a question. I'm simply trying to connect 2 terminals together on my GoPro camera (ground and on/off button), using the Basic Stamp Homework board. I've come up with a few different ways to do this, that's pretty easy. The problem is, when the camera is turned off by the board, and I remove the battery from the board, the camera turns back on, like the I/O pin sees a spike when there is a reset or a power cycle.

Is there a way around this? Different board? Use something like an OP AMP to isolate?

Thanks for the help!

Leigh

Comments

  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2012-07-12 09:28
    I suspect what you have is the BasicStamp forgets everything when power is removed. Not sure if a spike occurs on a disconnect. It could be that the capacitors and the low drop out voltage regulator may create one, but I strongly doubt so.

    You could have the BasicStamp put itself into low power mode with SLEEP, NAP, or END before you remove the battery. I think having a BUTTON command that jumps to an END is the best solution.

    If you want to have something switch that will remember without any power, you need a little latching relay that is controlled by the BasicStamp. But that is only as a switch. Your camera may actually be responding to a pulse - pulling a high to ground.

    Latching relays remember position even when power is removed from their coils. Erco mentioned some at Electronic Goldmine that are 5vdc and cost only $1USD or so.

    The camera's ON/OFF button may actually be just using a pulse in a way similar to a latching relay, but it has a battery to power the electronic latch. Alternatively, a LOW may cause the camera to turn ON and a HIGH may cause the camera to turn off. You need to be sure how this switch really works.

    OpAmps and Comparators or even logic flip-flops might work, but only as long as they have power - no power, no memory.
  • willembadwillembad Posts: 47
    edited 2012-07-12 12:26
    My GoPro is a Hero1 and the power button is a momentary switch. The camera obviously polls this switch and looks for a trigger to either turn on (short press) or off (2 second press). Do you know if the camera looks for a high or low state? This same switch also does other things depending on what mode the camera is in. To make this work you will need to know if the camera is responding to high or low and also what voltage the threshold is.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2012-07-13 02:35
    A momentary switch is likely central to the problem. The BasicStamp goes into limbo on shut down and may provide enough of a voltage transition to trigger the camera.

    Somehow, this need to be defined. A pullup or pulldown resistor of 10k may just be the simplest item. But if you remove the battery, a pullup from the BasisStamp power won't help anything.

    All that talk of latching relays is about switching, not pulsing.
  • lpettipalpettipa Posts: 2
    edited 2012-07-16 07:39
    Thanks for the help. The relay worked out perfect. Got a 5v relay at my electronics store for $4.

    I used the relay circuit diagram from the Dual Relay Board Kit.

    The problem with the GoPro camera that was tricky to get around was: a 1ms low pulse will turn it on. The Stamps I/O work great when it is powered up (same as turning an LED on or off), but at power on or off (removing/installing 9v battery in my case), there must be a low pulse. With the relay, this power on/off pulse is not enough to close the contacts, so the camera now has no idea this is happening.

    Again, thanks. Leigh
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