1 Dec
2008
1 Dec
'08
8:10 p.m.
On Tue, 2 Dec 2008 00:38:14 +0100
Nick Copeland <nickycopeland(a)hotmail.com> wrote:
Grey code encoders are expensive for what they are. If you use an
incremental encoder, resolutions go up to 5000 pulses per revolution.
If you only want relative change and direction just use A & B
In one direction A comes before B, and vice-versa.
If you need absolute position, you get the index reference (designated N
or Z) once every revolution. If you intend to use less than one
revolution just make sure the index pulse is right in the middle of
the most used range and have your software reset the value each time
it's seen.
--
Will J Godfrey
http://www.musically.me.uk
For regular 7-bit stuff, I'll be using a
16-input, 8-bit ADC. However,
in order to get higher resolutions for the 2 x 7-bit messages, I am
dropping analogue input in favour of rotary encoders.
Nice. Are they optical? Suppose they must be. The Moog Source used optical rotary pots
yonks ago to overcome numerous issues. What is their resolution? I always thought they
were quite coarse since the optics has a limit on the width of the shadow being cast but
that depends on how the comb wheel is etched and how the leds are aligned, admittedly you
do have the benefit that you can just spin the dial to get higher resolution since they
don't have a start or end point. You may still get noise depending on the scanning
rate and line width - if the scanning rate is too slow you can get spurious direction
changes since you only have a 2 bit grey coding. I would be very interested to hear your
results, they are cool pieces of hardware.
Regards, nick.