Re: Light sensor on XO-1.75

2011-09-02 Thread Paul Fox
sascha wrote: > > > yes, it's a nice trick. i think it was discussed on this list last year. > > it's not very sensitive, but it can tell us the difference between full > > sun and not, which is really when we'd want to turn off the backlight. > > Given that turning off the backlight usual

Re: Light sensor on XO-1.75

2011-09-02 Thread Sascha Silbe
Excerpts from Paul Fox's message of Tue Aug 30 16:38:13 +0200 2011: > yes, it's a nice trick. i think it was discussed on this list last year. > it's not very sensitive, but it can tell us the difference between full > sun and not, which is really when we'd want to turn off the backlight. Given

Re: Light sensor on XO-1.75

2011-08-31 Thread John Watlington
On Aug 29, 2011, at 7:52 PM, James Cameron wrote: > On Mon, Aug 29, 2011 at 07:38:20PM -0400, Richard Smith wrote: >> On Mon, Aug 29, 2011 at 1:06 PM, Bert Freudenberg >> wrote: >>> And it seems to sit "behind" the blinking left-most LED? And the >>> blink rate is proportional to the light sens

Re: Light sensor on XO-1.75

2011-08-31 Thread James Cameron
Please review http://wiki.laptop.org/go/Light_Sensor On Mon, Aug 29, 2011 at 07:06:32PM +0200, Bert Freudenberg wrote: > And the blink rate is proportional to the light sensed? Why? The sensor is a reverse biased LED. The LED is charged in reverse polarity, which makes the junction behave like a

Re: Light sensor on XO-1.75

2011-08-31 Thread James Cameron
On Mon, Aug 29, 2011 at 07:38:20PM -0400, Richard Smith wrote: > On Mon, Aug 29, 2011 at 1:06 PM, Bert Freudenberg > wrote: > > 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 s

Re: Light sensor on XO-1.75

2011-08-30 Thread Richard A. Smith
On 08/30/2011 09:50 AM, Bert Freudenberg wrote: 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. Ah, so you use the LED itself to sense light? And then time how long a cycle takes

Re: Light sensor on XO-1.75

2011-08-30 Thread Paul Fox
bert wrote: > > On 30.08.2011, at 01:38, Richard Smith wrote: > > > On Mon, Aug 29, 2011 at 1:06 PM, Bert Freudenberg > 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 th

Re: Light sensor on XO-1.75

2011-08-30 Thread Bert Freudenberg
On 30.08.2011, at 01:38, Richard Smith wrote: > On Mon, Aug 29, 2011 at 1:06 PM, Bert Freudenberg > 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/devi

Re: Light sensor on XO-1.75

2011-08-29 Thread forster
> Is the compass exposed, too? Is there a list of all the sensors and how to > access them somewhere? > There is an incomplete list of devices at http://wiki.sugarlabs.org/go/Activities/TurtleArt#Device_I.2FO Tony ___ Devel mailing list Devel@lists.la

Re: Light sensor on XO-1.75

2011-08-29 Thread Richard Smith
On Mon, Aug 29, 2011 at 1:06 PM, Bert Freudenberg 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 "b

Re: Light sensor on XO-1.75

2011-08-29 Thread Paul Fox
bert 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?

Light sensor on XO-1.75

2011-08-29 Thread Bert Freudenberg
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