How to set the screen brightness lower on Alcatel One Touch Evolve
The backlight of the Alcatel One Touch Evolve won’t get any dimmer if you set the brightness below 40 or so (out of 255). I tried RootDim, and it didn’t work any better. Neither did
echo 10 > /sys/class/leds/lcd-backlight/brightness
Any values before 40 look as bright as 40 does. But this works, if you are rooted:
echo 20 > /sys/class/leds/lcd-backlight/brightness
echo 3 > /sys/class/leds/lcd-backlight/duty
"duty" apparently designates the pulse width modulation duty cycle. Setting the duty cycle to anything between 3 and 20 will make the screen dimmer than the minimum setting you can get with the normal brightness controls. Setting to 2 turns the screen entirely black, on my phone. The maximum value is 63.
Another way to set this is in the engineer mode that you can access by dialing *#*#3646633#*#*. Swipe to “Hardware Testing” and select “Display.” You can set a PWM duty cycle on that screen. I don’t know whether your phone needs to be rooted for this method to work.
No matter how you set it, it is a temporary change and will be reset next time the screen brightness changes, or if you turn your phone screen off and back on.
Does anyone know of an app that does this? There are plenty of auto brightness apps, and some brightness apps that require root, but I don’t know of any that set both the brightness and the duty cycle. I have some shell commands set up in Tasker, but it’s not very convenient. I could try creating a widget using Tasker, but I may just try writing my own app.