Ok here is a wierd one! I just bought a new projector for our rear wall/ confidence monitor at our church. and even though it is a low budget, it has an auto ON feature! It senses a Incoming VGA signal, and turns itself on!
Which gives me an idea! I can turn on the front projector with serial commands, and i also dabble with the arduino. seeing that the arduino has a serial port, to which i could configure to send the serial power on command to the front projector.
I'm thinking if i could get the arduino to detect a vga signal, then use that detection to trigger a serial command to turn on the projector. that way when i turn on the computer, the arduino will detect the vga sginal, and power my projector automaticily for me! Anybody have any idea how to detect a vga signal turning on?
I have no idea how to implement ic2. do you have a quick down and dirty schematic / code example? also this wouldn't interfere with the signal transmission?
I'd worry more about interfering with the controlled impedance of the VGA's signal lines than the relatively slow I2C bus. You don't have to actively participate, just watch for the data or clock signal to toggle. That will tell you the monitor is trying to talk to the projector.