On 2019-08-07 13:40, Dave Liquorice wrote:
> On Tue, 6 Aug 2019 20:17:42 +0100, Adrian wrote:
>
>> I've tried unplugging the gauge, but I still get the problem, suggesting
>> GPIO rather than the gauge itself.  Stopping and restarting the software
>> appeared to help for a couple of days, but it has started again.
>> Rebooting doesn't work either.   The Python3 code below is started at
>> boot up, and can be run with nohup.  Any suggestions on where to start
>> looking ?
>
> Had any thunderstorms recently? Suspect a hardware problem, damaged
> GPIO input, or the built in pull up/down resitors fried. A floating
> input can produce a stream of false transitions. Either try another
> GPIO for the guage or fit a 10 k or so pull up/down resistor as
> required.
>
> Then think about adding some protection to try and reduce the chances
> of the Pi getting zapped again.
>

moisture and bad ground connections also a possbility.  months of
"sitting there" and you get galvanic corrision.  If it's anywhere near
rain, you might need to use some kind of coating to waterproof it.

Moisture plus electricity (even low current) can lead to galvanic
corrosion, tin whiskers, mold, leftover flux turning into a conductor,
insulation breakdown, lots of very bad things.

additionally, the idea of an external resistor (where you were using an
internal pullup/down resistor) is probably a good idea anyway, to help
protect electronics against static discharge and noise in general.


--
(aka 'Bombastic Bob' in case you wondered)

'Feeling with my fingers, and thinking with my brain' - me

'your story is so touching, but it sounds just like a lie'
"Straighten up and fly right"

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