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Voltage on an input preventing to boot ??

  • Hi,

    My Omage has a stange behaviour since today, that was not happening before...

    It looks like when there is a 4.5V voltage on GPIO 18 and 19 at boot time, the Omega does not start. At least, the LED does not light.

    If I put this voltage to only one of GPIO 18 or 19, it starts.

    If after the LED has lit, I put this voltage on GPIO 18 and 19, then no problem.

    However in a separate post, Lazar told that he could test 5V on an input without issues (https://community.onion.io/topic/381/electrical-specs/5)


    1. could it be that a too high voltage on these inputs prevents the Omega to start?
    2. do you have any clue why it was working until yesterday, and no more now?

    Thanks for any help, I am struggling with this and don' t understand what"s wrong.

  • Hi,
    adding another strange thing I noticed: the 1.8V pin outputs 3.4V, and it is not connected to anything. I Never measured it before, but it might give a hint to my problem.

    Please help with any idea

  • Hi,

    I think I have more or less understood what happened:

    • whenever I plug 5V to any GPIO, the 2.0V pin (type in my previous message : read 2.0V instead of 1.8V) outputs 3.4V, just like the GPIO17
    • and in that case, the Onion does not start (the LED does not light or blink).

    If instead of plugging 5V on a GPIO, I plug a 3.3V signal, then things seem to be OK, and the Omega boots.

    Now I have discovered a new thing, is that despite the Omaga starts its own Wifi, the former IP ( in my case) is not accessible from my home Wifi, and I had to reconfigured the Wifisetup through a Serial connection.

    It looks like I have made a wrong wiring 2 days ago, where I plugged a connector of my home-made PCB the wrong direction, and my guess it has partly damaged the Omega, and make it forget its wifi settings...

    Though I am not sure (I would understand it has been completely destroyed, but only very partially as it seems to be for me, seems very strange), any feedback from anyone here is welcome.

    Best regards,

  • administrators

    @Frederic-Baumann Interesting... My theory is that when you plugged in the home-made PCB connector it initiated a factory restore (by droving a logical high voltage on GPIO11 for ten seconds or more). Were any of the other settings reverted to their defaults?

    And to clarify if I understand your findings correctly:

    • Driving 3.3V to a GPIO before boot allows the Omega to boot successfully
    • Driving 5V to a GPIO before boot stops the boot sequence?

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