Light sensor on XO-1.75

Richard Smith richard at
Mon Aug 29 19:38:20 EDT 2011

On Mon, Aug 29, 2011 at 1:06 PM, Bert Freudenberg <bert at> wrote:
> On 17.08.2011, at 17:24, Martin Langhoff wrote:
>> Saadia Baloch (4):
>>      Driver to read Outdoor Light Sensor from EC on OLPC.
> So this is exposed at
>        /sys/devices/platform/olpc-ols.0/power_state
> And it seems to sit "behind" the blinking left-most LED? And the blink rate is proportional to the light sensed? Why?

Its proportional because that's how  the sensor works.  The amount of
light changes the time to bleed off the charge stored in the diode
when you reverse bias it.

Richard A. Smith
One Laptop per Child

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