New on Anelok TV: capacitive sensing

Werner Almesberger werner at
Wed Apr 30 03:29:12 EDT 2014

Felix wrote:
> infinite mechanical life

Yup, designed for immortality  :-)

> The use of the same area for slide and "click" touching could be prone to
> click mistakes by accident. I believe they should be separate zones.

Complete separation would eat a lot of precious space and possibly
even need more conannts. But how about the concept I posted last
year ? There's just one sensor but different areas of it have
different roles:

More details:

The bit about "one variable" was wrong, as I now realize. There are
good reasons for having a little apparent redundancy.

> I'm curious about this, why you discarded the other slide design?

You mean the three triangles on a sawtooth ? I didn't try it because
I wanted to first see how a simpler sensor would work. I now also
understand that the electrode design isn't so great, because I would
get three poorly correlated channels, making it very hard to remove
the common mode disturbances.

Freescale have a nice text on sensor design that also treats some
real-life issues. Multi-channel slider designs are shown on pages
19 and 20:

Surprisingly, they don't mention the double triangle design they
use on their FRDM-KL2xZ boards.

- Werner

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