Light sensor

Richard Franks richard.franks at
Thu Nov 30 17:05:04 CET 2006

On Thu, 2006-11-30 at 09:48 +0100, Sven Neuhaus wrote:
> Sean Moss-Pultz wrote:
> > > On 11/30/06 3:32 AM, "Robert Michel" <openmoko at> wrote:
> >> >> But this light sensor could also combined with localisation, time and
> >> >> provile (or movement sensor)
> >> >> E.g. when I'm at home and the light sensor detects light at 2 o'clock
> >> >> in the morning, I will still be reachable for calls from my frinds.
> > >
> > > Combined with automatically switching profiles (AGPS stuff) this is
> > > really an amazing idea.
> Agreed - fascinating possibilities! FYI, the Motorola L2 phone has a light
> sensor (it toggles the keypad light), so it's been done already, but - of
> course - the closed software on that phone doesn't fully utilize it...

I'm assuming that acquiring/monitoring the microphone input doesn't come
for free.. but ambient noise level could also be used as an indicator of
activity - either polling for one second every minute or so, or (if the
ADC can be directed to acquire at a lower data rate) a continuous sample
over a longer period of time -- you don't require too much resolution to
monitor the presence of ambient noise.

You would want to base it on an probabilistic analysis in either case,
else it might pick up car headlights swinging across the window, a
neighbours security light being triggered by raccoons, etc.

Oh wait, that wouldn't work... if you had the phone in the bedroom it
would allow incoming calls if you were snoring.



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