Dimmer offers a fast and easy way to adjust the brightness of your displays and it can dim all your screens and monitors LCD, TFT and LED backlit types (even old CRTs). This becomes very useful when you are in near/total darkness and the minimum brightness from your display or screen is still too much. The ddcutil capabilities command in that tutorial did not offer me helpful information, so don't give up based upon what you see there.Brightness control software for all your monitorsĭimmer is a small and free application for Windows, designed to help control the brightness of your computer screen, monitor or display. The above is a quick-and-dirty intro, based on ddcutil docs, man ddcutil, and a helpful page here: This is a lack in monitor manufacturers and not the software. One of my monitors requires multiples of 10 for brightness. Sometimes the values need to be converted to decimal. Sometimes it expects exact numbers even though it has a range. Note: many of the VCP codes did not work or not work as expected for me. Again, worst case scenario, but definitely something to be aware of. In general I wouldn't recommend writing more often than that and turning any automation off at night (+3 years) or when you're not using the machine. Worst case scenario is probably 100k writes, so if you write every thirty minutes you have about six years. IMPORTANT: monitor settings are generally stored in a way similar to an sd-card (e.g., EEPROM). Assuming is 20 the command to set brightness (0x10) to 50% would be: You then have everything you need to dim your screen. VCP code 0x10 (Brightness): current value = 63, max value = 100 For brightness it might be something like: The VCP code hex is what you want - specifically the two characters after the x. Then you can see what is (technically) available using: Then after rebooting (Buster) you can see more information and get the correct bus IDs using:įor each device you need the number after /dev/i2c. (to undo this just reverse fkms and kms in the above command) Sudo sed -i "s/dtoverlay=vc4-fkms-v3d/dtoverlay=vc4-kms-v3d/" /boot/config.txt You can probably run ddcutil detect here and get something back so you know you're on the right track but I needed to also replace fkms with kms in /boot/config.txt on Buster, not Bullseye and reboot: The short summary (AKA "worked for me on Pi4 latest Raspbian Buster and fresh Bullseye"): If your monitor supports DDC you can use ddcutil which has an entire page for Raspberry Pi. I had been looking for a solution for some time and this is one of the search results I kept hitting, so I thought to share the solution I found here so others could use it. Thanks to Dmitry Grigoryev for pointing the way in his answer. Note: I want to change brightness, no matter how - through gui/command line. HDMI-2 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 477mm x 268mmĢ) Try: xrandr -output HDMI-2 -brightness 0.1Īlso I tried xbacklight, but it doesn't see external monitor: $ xbacklight -getĪlso checked : ls /sys/class/backlight/, but the folder is empty. HDMI-1 connected primary 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm Question - how to change brightness of a screen? I install Raspbian OS, and connected HDMI monitor to one of micro hdmi ports on raspberry pi 4.
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