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.

    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…

  2. 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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