Color NTSC video directly from an AVR chip

color-ntsc-from-avr-chip

We’ve seen composite video out from AVR chips many times before. But we can’t remember coming across one that managed to produce a color signal. This project does just that, producing a color video signal from an ATmega168 without using external integrated circuits.

[CNLohr] is seen here showing off his accomplishment. You’ll remember him from the glass-slide PCB server project he’s been working on recently. This time around it’s a small piece of gaming hardware which he’s working on. But using four pins from the microcontroller, connected via resistors in parallel, he is able to generate a color NTSC signal without using a chip like the AD723.

After the break you can see the two minute demo in which he shows the game running for just an moment, then gives a general overview of how the signals are being built. There isn’t a ton of explanation, but he did post his code as well as a resource for you to teach yourself more about the NTSC standard. Maybe you can make a color version of that AVR tetris game?

[via Reddit]

27 thoughts on “Color NTSC video directly from an AVR chip

  1. The old APPLE][ did a nice job of color NTSC. A few peeks at those schematics OUT OF THE 80’s from a few geeks IN A GARAGE would help anyone taking a shot at this. For some truly serious good hacking though, take a look at the beautiful state machine they used to create the controller card for the DISK ][. The elegance was phenomenal.

    We need more such garages. Hackerspaces aren’t anything like that garage.

  2. Uhm, OT, but what’s this whiteboard he has in his hand, and why it looks like USB-connected? :) Or is it just a sheet of paper glued to a laptop or something? :)

    1. Well spotted, I had to go back and look again. Maybe it’s just some shiny white plastic film applied to the lid of his laptop so as to make it into a whiteboard – and which isn’t such a bad idea, hmmm…

  3. Atmega168 Max Operating Frequency: 20 MHz

    “This requires a 28.636 MHz Crystal!”

    Hmm.

    He also goes on to say:
    “This can be done even easier by using a PWM output signal. ”
    Does PWM even work on an overclocked avr? For sure ADC and eeprom is not going to work.

    1. I actually use eeprom and the ADC on another project overclocked the same without any issue. But, my sample size is small. It may be flaky and I don’t know it. The PWM CERTAINLY works, though.

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