[maemo-developers] [maemo-developers] n800 LED interface

[From: David Weinehall]

On ons, 2007-01-31 at 20:48 -0500, ext Larry Battraw wrote:
>   First off, kudos to the maemo team for making such a nifty and
> easy-to-use interface for the keypad LED.  I spent a inordinate amount
> of time just tinkering with the brightness, blinking period, and so
> forth :-)  For those interested, the relevant sys entries are here:
> /sys/class/leds/keypad
> Should be self explanatory, particularly if you turn on the blinking
> from the control panel so you can cat out the values it uses for
> delay_off and delay_on, etc.
>   My question is this: for the default trigger source (timer), is the
> blinking just a hardware PWM built into the CPU or is the CPU involved
> in counting timer interrupts to handle on/off periods and toggling the
> LED?  I ask because there was some discussion on ITT about how someone
> had their n800 run down overnight with the LED left on.  It seemed
> unlikely but I wanted to make sure a bunch of CPU cycles weren't being
> burned to run it.

To avoid conflicts with the LED-patterns already in use on the device,
I'd suggest using the LED-framework.  Simply add your pattern
to /etc/mce/mce.ini, and use the D-Bus interface to enable/disable the
pattern.  That way you'll get full control over priorities between
different patterns, the possibility to disable certain patterns when the
display is on, etc.


Regards: David