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Raspberry Pi Forum auto-oscillating Pi gpio pin--Where does it come from, can I stop it?
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Forum Thread Details
  • Replies 9 replies
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  • gpio_gclk
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auto-oscillating Pi gpio pin--Where does it come from, can I stop it?

jimjulian
jimjulian over 10 years ago

Hello,

 

  I've been using my Pi for exploration of the idea of a SoC. The only device I've ever connected the Pi to was an eight channel relay board. You've probably seen them, they're almost ubiquitous. They use the Songle relays in groups of 2, 4, 8, and 16.

  I had been trying out different software arrangements, such as MyPi, iControl, pi-blaster, Cayenne, WebIOPi/Weaved, and somewhere along the line my Pi's GPIO_GCLK pin stopped responding. Eventually, I removed the wiring from the relay board end and reconnected. This time, the pin worked...sort of.

  The pin generates a pulsed signal about every ten seconds that lasts two seconds. The two second interval is filled with 50% duty cycle 0.03 second on-off switches.

  I have no idea where the signal is coming from but I'm beginning to suspect that the pin's function as GPIO_GCLK has something to do with the situation.

If anyone knows what is happening, or has any ideas on how to proceed, please feel free to post.  All comments are appreciated.

 

Thank you,

Jim J

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  • balearicdynamics
    balearicdynamics over 10 years ago

    Hi Jim,

     

    I try to guess that something almost random may occur if you don't use a pull-up or pull-down resistor to force the default status of the digital pin. I see things like this but more and more frequent happening to the Arduino boards if in some conditions the I/O signal is left floating in one of the two states.

     

    Enrico

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  • jimjulian
    jimjulian over 10 years ago in reply to balearicdynamics

    Hello Enrico,

     

       Thanks for responding.

       If the pattern weren't so regular, repetitive, and predictable, I would make that my first theory of cause.

     

    Thank you,

    Jim

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  • jimjulian
    jimjulian over 10 years ago in reply to balearicdynamics

    Hello Enrico,

     

       Thanks for responding.

       If the pattern weren't so regular, repetitive, and predictable, I would make that my first theory of cause.

     

    Thank you,

    Jim

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