Electronics > Projects, Designs, and Technical Stuff

VGA Monitor Interface


Hey guys!

I'm designing a simple 2 lead ECG/EKG machine and I need information on interfacing it with a standard VGA monitor, I'm using a ATMega 48 micro.
So far all the information I've found is rather vague and/or confusing, so if anyone can point me to a good article that would be great.  :)
Any help on this project is much appreciated, I will be releasing the source and schematic for everyone to enjoy.

It's quite simple really. You only need 5 signals:

* RED - Analogue
* GREEN - Analogue
* BLUE - Analogue
Sync signals depend on the resolution and refresh rate you want to use. As you are using a micro, you'll have limited choices (640x480 @ 60Hz requires 25MHz pixel clock!).
The colours are analogue and their intensity depend on voltage.

I attached a part of my report, which discusses the implementation of VGA interface. It does not go into details of monitor operation though. You can find that information here: http://books.google.com/books?id=mwUV7ZK9l9gC&lpg=PP1&dq=fpga%20prototyping%20by%20vhdl%20examples&pg=PA257#v=onepage&q&f=false

Thank you that helps a lot.

You are going to have your work cut out generating VGA with that chip. Maybe you could get TV resolution but 640x480 is pushing it. Epson used to have a great video generator chip, the S1D13806 which had onboard video memory. 4dsystems in Australia do a nice little graphics chip too: http://shop.4dsystems.com.au/38-vga-embedded-vga-graphics-modules

Doing it at a low resolution may work, but just to scare yourself a little, you have to output 3 values at pixel-clock ~= 1.5*{width}*{height}*{vrefresh}, I did once drive a VGA monitor with an Spartan3 FPGA @ 1024x768x60, but it was all done directly, no buffers and in 3 bits of colour (our board did not have DACs AFAIR).

The board that Zad mentions looks neat, or maybe use a salvageable RAMDAC from a old videocard too.



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