Sdftdssetggh
Posts: 7
Joined: Tue May 08, 2018 5:50 pm

Raspberry pi 7”touchscreen brightness

Mon May 21, 2018 2:26 pm

Hi , someone can explain me how to set screen lightness on my raspberry touchscreen ?
I’m using a rpi 3 model b and I have installed raspbian

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DougieLawson
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Location: Basingstoke, UK
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Re: Raspberry pi 7”touchscreen brightness

Mon May 21, 2018 5:48 pm

Assuming this is the official RPF 7" touch screen and not a V1.0 model. There's a virtual filesystem
/sys/class/backlight/rpi_backlight

In there you've got

Code: Select all

[email protected]:/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
[email protected]:/sys/class/backlight/rpi_backlight $
A root user can write to the brightness file.
sudo sh -c 'echo "128" > /sys/class/backlight/rpi_backlight/brightness'

Values run from 0 (dark) to 255 (full brightness).
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Sdftdssetggh
Posts: 7
Joined: Tue May 08, 2018 5:50 pm

Re: Raspberry pi 7”touchscreen brightness

Mon May 21, 2018 6:22 pm

I tried to set 255 but the brightness still low , but it changes When I set different values .
Yes , it is the official display

helioz2000
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Joined: Sun Jul 22, 2018 2:19 am
Location: Australia
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Re: Raspberry pi 7”touchscreen brightness

Sun Jul 22, 2018 3:02 am

DougieLawson wrote:
Mon May 21, 2018 5:48 pm
Values run from 0 (dark) to 255 (full brightness).
I'm no guru on this subject, but ........
My lab test shows maximum brightness around 200, whereas 255 is actually slightly dimmer than 200.
This finding also corresponds with measured current consumption which is around 85mA higher at the 200 setting than the 255 setting.

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