anelok user interface

Werner Almesberger werner at
Fri Sep 20 08:13:55 EDT 2013

Suresh P wrote:
> Why not a touch screen?

A few reasons:

- at that size, there's very little space for fingers, even if you
  make the touch area a bit larger than the display,
- may be quite difficult to find a touch panel of that size (and I
  don't think it's something one could DIY),
- very limited haptic feedback,
- if resistive, you have to choose between protecting the display's
  glass and closeness of the touch panel plane to the display
  plane. If capacitive, the technology gets complicated.

In any case, a touch panel would complicate the mechanical stacking.
Mechanics are where us Open Hardware types are the weakest, so I'd
tread very carefully where.

> My idea is:

Hmm, that seems to be a somewhat different and probably larger
device. If you want to try something with a touch screen, I don't
think you really need hardware buttons besides it. Just make the
panel larger than the display, then print your "hardware" buttons
under the touch panel.

> 3. Every third unsuccessful attempt to hard unlock will factory
> reset the device clearing all the data.

I never liked those "three tries and you're dead" systems. They
also allow for denial of service attacks. I'd just enforce
increasingly larger delays and have a higher threshold for tries.
You still need one in case someone manages to tweak the delays.

Of course, all this can be made configurable, a firmware build
option, you could have an alternative firmware, etc.

- Werner

More information about the discussion mailing list