Monday, May 2, 2011

How to Disable the Automatic Light Sensor on the Cr-48

The Automatic Light Sensor (ALS) on the Cr-48 is responsible for reading current light conditions and adjusting the display backlight appropriately. Unfortunately the sensor is a little to sensitive for some user's taste. Until Google gets the sensor setting right or allows us to disable and adjust the sensor from the GUI settings, it's possible to disable the sensor entirely. Just get a shell prompt and run:

echo 0x29 | sudo tee /sys/class/i2c-adapter/i2c-2/delete_device

this disables the light sensor so that the backlight is not adjusted with changing light conditions. You can still adjust the backlight using the dim and bright buttons above the 7, 8 and 9 on the keyboard and the display will still dim after a period of inactivity. Disabling the ALS is temporary, it'll be re-enabled after you reboot and you'll need to re-run the command. Feel free to share your experience with the ALS in the comments below.