From what I have read on the RG-11, you likely need a pull-up resistor at the RG11_PIN input of the HUZZAH. A 4.7k or 10k resistor connected to the HUZZAH 3.3 volt supply may be all that's needed, even though you specified INPUT_PULLUP with pinMode (internal pull-up may be too weak). The other output pin of the RG-11 would go to ground so, either the signal would float high with the pull-up, or would be brought to ground.
The other thing I noticed is that 'RG11_PIN' does not seem to be defined in rg11.h. It may be defined elsewhere but it's not clear.
Thanks for the input - yes, the constants are defined in config.h per Wolgang's original. I'm not actually testing using the RG-11 just yet, thought I would get my logic and programming right on the desk before I move to the actual unit - the RG-11 works by closing a relay when rain is detected so it's a pretty simple "switch" - which I am planning on running in an NO configuration - closing on rain - but do you think I can get my code to work reliably? Not sure if it's an electrical thing or a programming thing or both!
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