We live in 10% or less relative humidity, where electrostatic
discharge is the most common cause of equipment failure.  We have
exposed grounds everywhere to touch.

Our kitchen timer [1], for $4, has an LCD display and three touch
sensitive areas below it; marked minutes, seconds, and start/stop.  It
is continually powered by a pair of AAA cells.

To program the timer we press minutes or seconds until the right time
is shown, then press start/stop.

We used to be able to press start/stop at any time, but after a recent
electrostatic discharge, start will only work if we recently pressed
minute or seconds.

We used to be able to press start/stop at any time, while the timer is
running, but now we must briefly press seconds first.

Putting it another way, the only time that start/stop works is:

- within a second of pressing minutes or seconds,

- during the end of time alarm condition.

PIC, ARM, and AVR I/O pins often have separate paths for wakeup and
GPIO read.  I don't (yet) know what device this uses; probably a cheap
8051 clone.

Does this sound like an ESD failure of the wakeup path?


--

1.  (the timer is branded "propert", was purchased from Woolworths,
Australia, a sample photograph by someone else:
http://oi46.tinypic.com/5kmvjl.jpg )

--=20
James Cameron
http://quozl.linux.org.au/
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