GPIO 0.3volts taking it HIGH?



  • Hi all,

    I've got a strange problem with GPIO on an Omega2.

    When I test my input through a digital test meter I see, at most, 0.3v coming from the equipment I am connected to. However the documentation for the Omega2 seems to say that you should only see a high input when it it goes above 2.0volts.

    Example:
    https://gfycat.com/BrokenRectangularDorado

    Any idea what is or could be going on?
    When the connected equipment goes high (outputs 3.3volts) I see a constant HIGH on the Omega2 GPIO but it is slightly annoying seeing the LOW as as "flapping" between high and low.

    I can only assume interference from mains wiring that runs alongside the twisted pair that I'm using to connect my equipment to the Omega2.

    Any suggestions would be lovely.



  • It may be that your "low" is not actually driven, but just a floating line.

    Or it may be that it has occasional high pulses on it, and the meter is only reading a crude (and perhaps very misleading) sort of sampled time average.

    You could try a pull-down resistor to give an undriven line defined state, but it would be best to understand what the unspecified equipment is actually doing electrically - not just from an operational point of view but also the possibility of it doing something damagingly out of specification, or driving the line high when the Omega 2 is unpowered, which can also be problematic.



  • It is connected to a commercial gas boiler system. The terminals it connects to claim to just be a certainly doesn't output anything like AC or high DC when triggered. All the wiring does run directly alongside the main AC electricity feed into the boiler though.

    I will see if I can borrow an analogue test meter and see if I can see it wobbling around.


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