From: Keith Wootten
Subject: Re: circuit wanted-SQUARE PULSE GENERATOR
User-Agent: Turnpike/6.02-U (<7r9OMDU2ooRJCQmjnYJxyjtHfm>)
X-Inktomi-Trace: pc3-rdng1-6-cust147.winn.cable.ntl.com 1038351687 7329 220.127.116.11 (26 Nov 2002 23:01:27 GMT)
Date: Tue, 26 Nov 2002 23:00:55 +0000
NNTP-Posting-Date: Tue, 26 Nov 2002 23:01:27 GMT
Organization: ntl News Service
In message , Leon Heller
>One could do that with just two buttons. For instance, while one button is
>pressed the other button toggles between coarse/fine modes.
I used something similar for manual hydraulic ram positioning - one
button for up, one for down. The ram may be a long way off position
initially, but you need very fine control for the final positioning.
Initial pressing and holding in of one button goes at the slowest rate,
and subsequent momentary pressing of the other button increases the rate
by 2x up to some sensible maximum. Reset to slowest when both released.
It may sound tricky, but it actually works very well, and the users like
it. Better than separate coarse/fine buttons, single hand operation is
easy without looking.
>I keep meaning to see how far one can take a two button interface. We used
>to joke about using just two buttons to control a copier when I worked on
>interface design at Xerox Research (UK).
It can be hell. Eurotherm temperature controllers worked on some fairly
minimal button arrangement and were notoriously difficult to use unless
you were practised.
I once designed a system which replaced two 19" bays of knobs and
switches with five buttons, an encoder and a 64x240 pixel graphics LCD.
Lots of menus with icons, but you couldn't see at a glance what all the
settings were. Some of the top level menus were simply there to 'expand
the tree' to access the functional multiple lower levels. Not so good,
although the encoder was well received.
>A lot can be done with one button, if it's used to send Morse code to the