Step 5: Software and Projects
Unfortunately this adapter scheme is not compatible with all systems. Support for DDC is not mandated, so not all video cards support this capability. I've had good luck thus far with Mac systems that have ATI or Intel graphics chips, but NVIDIA-based systems are out of luck. On the Linux side I've only successfully tested an IBM ThinkPad A31p (ATI graphics), but it would not work with an Asus EeePC (Intel).
The images here show a test rig that demonstrates various I2C devices in action. The computer continually reads the ambient temperature from an I2C temperature sensor, periodically logs this data to an I2C serial EEPROM chip (yes, it could just print to a file, but this was to further demonstrate I2C applications), and then a servo (through an I2C controller) serves as a makeshift indicator dial. With the library and sample code for these devices already in place, it only took a few minutes to put together this demo (and most of that was in making the indicator dial).