This project implements the DDC/CI protocol and aims to provide a base to add this functionality to monitors that do not support it.
Standart disclaimer applies. You must know what you're doing and must have a experience in electronics. I take NO RESPONSIBILITY for any damages. There are NO WARRANTIES, etc., etc.
Please don't do anything if you have no experience, this can be life-threatening.
The heart of the project is ATmega48. Other AVR MCUs can be used with minor code modifications, provided they have hardware TWI (I2C), PWM and some spare I/O pins. 4K flash or more is recommended.
MCU fuses should be set to:
The more or less final version of schematics is below (svn tag: "stable-2").
Connectors:
LED1 binks shortly when one of the following happens:
For testing purposes DDC bus can be connected to video card without monitor. For D-SUB, monitor presence must be emulated with 75 Ohm load on R, G, B lines.
Here's simple I2C probe for LPT port: http://www.boichat.ch/nicolas/ddcci/method.html
Tested with Crossover 27Q monitor (green led driver with lower minimal brightness mod). See image for information about where connect to. No additional components required.
Demo videos:
Linux:
Windows: