Raspberry Pi Forums

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pi@Challenger:/sys/class/backlight/rpi_backlight $ ls -la
total 0
drwxr-xr-x 3 root root    0 May 19 09:17 .
drwxr-xr-x 3 root root    0 May 19 09:17 ..
-r--r--r-- 1 root root 4096 May 21 18:46 actual_brightness
-rw-r--r-- 1 root root 4096 May 21 18:46 bl_power
-rw-r--r-- 1 root root 4096 May 19 09:17 brightness
lrwxrwxrwx 1 root root    0 May 21 18:46 device -> ../../../rpi_backlight
-r--r--r-- 1 root root 4096 May 19 09:17 max_brightness
drwxr-xr-x 2 root root    0 May 21 18:45 power
lrwxrwxrwx 1 root root    0 May 19 09:17 subsystem -> ../../../../../class/backlight
-r--r--r-- 1 root root 4096 May 19 09:17 type
-rw-r--r-- 1 root root 4096 May 19 09:17 uevent
pi@Challenger:/sys/class/backlight/rpi_backlight $

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# brightness.py  Version 0.1
# Copyright (C) 2019 Roy Leith 
# This program is distributed under the terms of the GNU General Public License V3

import rpi_backlight as bl
from Tkinter import *

def maxbl ():
	maxb = bl.get_max_brightness()
	return maxb
	
def statusquo ():
	value = bl.get_actual_brightness()
	return value / ratio
	
def setb (val):
	bl.set_brightness (int(int(val) * ratio))

master = Tk()
master.title('Brightness')
master.option_add('*font', ('verdana', 10, 'bold'))
	
maxv = maxbl ()
ratio = float(maxv) / 100
maxvalue = int(maxv / ratio)
Rvalue = statusquo()

brivar = IntVar()       
brivar.set(Rvalue)
brightness = Scale(master, from_=maxvalue, to=10, orient=VERTICAL, length=200, width=10,
    tickinterval=20, variable=brivar, command= setb,)

brightness.grid(row=0, column=0, sticky='NE')

mainloop()

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[Desktop Entry]
Name=Brightness
Comment=Brightness Control
TryExec=python
Exec=python /home/pi/Programs/Brightness/brightness.py
Icon=/usr/share/icons/Adwaita/96x96/status/display-brightness-symbolic.symbolic.png
Terminal=false
Type=Application
Categories=GTK;Utility

Code: Select all

How to add Brightness to your Raspberry Pi Official 7" touch display.
You will need to install two Python modules. 

The first is Linus Groh's rpi-backlight module released under the MIT License.

     pip install rpi_backlight

Second is tkinter,

     sudo apt-get install python3-tk

You will need to give your user permission to use the system files.
    sudo leafpad  /etc/udev/rules.d/backlight-permissions.rules

Insert the line::

    SUBSYSTEM=="backlight",RUN+="/bin/chmod 666 /sys/class/backlight/%k/brightness /sys/class/backlight/%k/bl_power"

Place the files, brightness.py, brightness.desktop and this 
Readme.txt file in a folder called,
 
     /home/pi/Programs/Brightness

If you have changed your user name, then replace the name 'pi'
in the above path and in the brightness.desktop file.

Please note that the file brightness.desktop will appear as the file 
Brightness, with a 'sun' icon.

Run the File Manager with root permissions,

     sudo pcmanfm

     and copy the file brightness.desktop to the folder,

     /usr/share/raspi-ui-overrides/applications

When you open the Applications Menu you will find the Brightness icon 
in the 'Accessories' catagory. Add it to the Panel by adding an 
'Application Launcher' Panel Item and editing it to use Brightness.