Re: [support-gang] XO brightness key operation
nicholas wrote: Is there a way to read the current value of the 1.75's ambient light sensor? It'd be neat if that could be displayed by an activity. there is. turtleart can do this, i believe. http://wiki.laptop.org/go/Light_Sensor#Programming paul =- paul fox, p...@laptop.org ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Re: [support-gang] XO brightness key operation
nicholas wrote: Is there a way to read the current value of the 1.75's ambient light sensor? It'd be neat if that could be displayed by an activity. there is. turtleart can do this, i believe. http://wiki.laptop.org/go/Light_Sensor#Programming see http://wiki.sugarlabs.org/go/Activities/Turtle_Art#Device_I.2FO ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: [support-gang] XO brightness key operation
Is there a way to read the current value of the 1.75's ambient light sensor? It'd be neat if that could be displayed by an activity. -- Nick Doiron Code for America On Apr 9, 2012 9:16 AM, Paul Fox p...@laptop.org wrote: i just sent this to the folks working on the current doc sprint, and then realized it probably deserves a wider audience. operation of the brightness keys was enhanced a bit in 11.3.1, based on discussion on the devel list, but i don't recall that i ever sent out a summary mail. for convenience, i'm going to refer to the brightness keys as BrUp and BrDown here. on all laptops, in all sofware releases to date: - the unmodified BrUp and BrDown keys adjust the brightness in 15 steps. when turning the backlight all the way off (i.e., the lowest setting) the display will switch into the higher resolution monochrome mode. - using the Alt-BrUp and Alt-BrDown combinations will immediately change the backlight to its maximum and off values (including the change to monochrome when off). in release 11.3.1 and later, on all laptops: - the Ctrl-BrUp and Ctrl-BrDown combinations don't actually change the backlight level, but rather will toggle the screen between normal mode and the higher resolution monochrome mode. this monochrome mode will be sticky, so further normal use of the keys will adjust the brightness but won't restore color. this can be useful if you want the higher resolution, and don't currently need to have color displayed. unfortunately, there is currently no way to enter this semi-permanent monochrome mode via the Sugar user interface -- only Ctrl-BrDown will do it. and finally, on XO-1.75 only: - the backlight may automatically turn off when the laptop is in bright sunlight. when this happens, it is _not_ put into the hi-res monochrome mode. when the light level returns to normal -- i.e., indoor or shady light -- the backlight will be restored to its previous value. the ambient light sensor shares the opening in the plastic with the LED that looks like (o) near the lower left corner of the screen, so covering that location when outside, or shining a bright light on it when inside, may cause the backlight level to change. it's also worth noting that the F9 and F10 keys are, by default, the brightness keys, and are intercepted by system software before a running program can receive them. if the Fn key is pressed at the same time as F9 or F10, then the keys instead generate the true F9 and F10 codes, and are available to the current application (or perhaps the window manager). this is also true of the volume keys on F11 and F12 -- on any of our keyboards, holding Fn will force the top row of keys to generate F1 through F12. finally: all of the above functionality is available from the shell commandline: $ olpc-brightness -h usage: olpc-brightness [up|down|max|min|0-15|color|mono] paul =- paul fox, p...@laptop.org ___ support-gang mailing list support-g...@lists.laptop.org http://lists.laptop.org/listinfo/support-gang ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Re: [support-gang] XO brightness key operation
Is there a way to read the current value of the 1.75's ambient light sensor? It'd be neat if that could be displayed by an activity. Yes its documented at http://wiki.sugarlabs.org/go/Activities/Turtle_Art#Device_I.2FO what you want I think is /sys/devices/platform/olpc-ols.0/level Tony ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: [support-gang] XO brightness key operation
Hi, On Mon, Apr 09 2012, Nicholas Doiron wrote: Is there a way to read the current value of the 1.75's ambient light sensor? It'd be neat if that could be displayed by an activity. Yes, /sys/devices/platform/olpc-ols.0/level You can read powerd's source on the XO; it uses a more complicated API involving setting limits of high and low light to change the backlight. - Chris. -- Chris Ball c...@laptop.org http://printf.net/ One Laptop Per Child ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: [support-gang] XO brightness key operation
G'day Kevin I was responsible for the idea to use an LED as a cheap light sensor on the XO-1.75, built the first prototype, and have been following the feature since. To use an LED as a light sensor requires a special connection method; either the LED must be mounted in reverse, or both terminals of the LED must be directly connected to software driven input/output pins on a microcontroller or CPU. Mounting the LED in reverse prevents it from being used as an indicator. Using two software driven pins is an additional cost if there is a limit on the number of pins available. The embedded controller has a limit on the current it can supply to LEDs. None of the LEDs on XO-1 or XO-1.5 are connected in a way that supports their use as a light sensor. All of the LEDs on XO-1 or XO-1.5 are connected to driving transistors or MOSFETs. This is so that two LEDs, front and back of the hinged section, can be driven at the same time, with a tiny current draw from the embedded controller. But driving these LEDs in this way also effectively prevents their use as light sensors. I suggest that if you want to experiment with using LEDs as light sensors, that you get yourself an Arduino or similar, and play with that. It is much easier than opening an XO and changing the wiring. ;-) -- James Cameron http://quozl.linux.org.au/ ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
