Detect VGA signal

Using Arduino Project Guidance
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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?
JR

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Video is approx 1v levels isn't it?

You could run the signal into a comparator to get a pulsed 5v waveform and interrupt on that.

Rob

3

Don't bother with the VGA signals, which are 75ohm paths. Pins 12 and 15 are i2c pins. You could just watch for activity on those lines.

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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?

thanks again, JR

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jreckart:
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.

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I had no idea VGA had I2C in the wire, always knew that the monitor could talk to the PC but didn't wonder how.

That will tell you the monitor is trying to talk to the projector.

But does that tell you there's a video signal?

Rob

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so does anybody have any ideas?

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HSYNC and VSYNC signals are a train of squared pulses of +5V (+3.3V serves too)

http://www.javiervalcarce.eu/wiki/VGA_Video_Signal_Format_and_Timing_Specifications

At Arduino, use pulseIn() to detect HSYNC or VSYNC signals, no need for both, flip coin to make decision.

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