Auto Brightness Control

An Arduino-based automatic brightness control system that adjusts monitor brightness based on ambient light sensor readings.

20251113_192941-00.00.00.000-00.00.14.891.mp4

Setup Process

1. Monitor Feature Code Discovery

• Used NirSoft's ControlMyMonitor to find feature codes for monitors:
  • XG27AQDMG
  • KG241Q P
• Tool: https://www.nirsoft.net/utils/control_my_monitor.html

2. DDC/CI Utility Setup

• Compiled winddcutil for Windows from their GitHub repository
• Repository: https://github.com/scottaxcell/winddcutil
• Uses Windows' SetVCP function to control monitor brightness via DDC/CI protocol

3. Usage Example

1. Run Ino with given code (autobrightness.ino)
2. Run brightnesscontrol.py - should be changing brightness now

Requirements

• Python 3.9.3
• Arduino with light sensor (I used an Uno R4 Wifi)
• Windows OS with DDC/CI capable monitors

How It Works

1. Arduino reads ambient light sensor values
2. Python script collects sensor data over 1.5 second intervals
3. There is a lag between requesting brightness to bet set, and it being set. Large enough to warrant buffering data and using it. Thus:
   1. Calculates median sensor value to provide a well-representive value every interval
4. Maps sensor values (0-1023) to brightness percentage (0-100%) with an offset added for a brighter bias preference.
5. Uses winddcutil to set monitor brightness via DDC/CI

Files

• autobrightness.ino - Arduino sensor code
• brightnesscontrol.py - Main brightness control script
• winddcutil.exe - DDC/CI utility for Windows