RE: Re: [Project] Kbd/LCD device

["Keith Doxey" <ukha@xxxxxxx>]

I bet that encoder cost more than 30 quid :-)

Keith

-----Original Message-----
From: Dr John Tankard [mailto:john@xxxxxxx]
Sent: 29 May 2001 16:54
To: ukha_d@xxxxxxx
Subject: RE: [ukha_d] Re: [Project] Kbd/LCD device



> I will see if I still have a catalogue I picked up at a trade
> show a couple
> of years ago. They had rotary encoders with a ring of LED's around the
> outside so you could use it to indicate the position a
"manual"
> pot would be
> at before you turned it.
>

VideoLogic DTS decoder uses them, but you have to do about half a turn to
move the led up a notch.

If we were using a graphic LED we could do a moving scale that is activated
when the encoder is moved.

As a subnote, I did a job which required to watch a 360 position encoder
(1440 edges), the encoder was to rotate at about 6 revs per second, I did
the code in FORTH with the decoding as inline assembler and despite my
calculations saying the micro was fast enough it did not work, in the end I
found the problem was the shaft was ending up 6 reves on but it was going
back and forwards  several times as well !  To get to the point I added two
HP decoder chips which gave me a 32 bit up down counter, which solved the
problem, It was a HCTL-20XX series works up to 14MHz and does the updown
decoding as well.

John





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