Like most of the folks that come to the annual Analog Aficionados party, my buddy Todd Bailey has a bunch of interests. Todd helped Atmel out at the NY Maker Faire working at our booth, showing off his Atmel AVR-powered video synthesizer.
Todd does a lot of work with AVRs, some of which I can’t tell you about because he is under NDA (non-disclosure agreement). The video synth was a personal fun project perfectly aligned with the open-source and Maker movement. The synth generates all sync, blanking, and colorburst signals on an Atmega168a running at 14.31818MHz (four times the color carrier frequency for NTSC). The one at the Faire was a prototype and Todd might move up to an Xmega just so he can run at 8 times the color carrier rate for tighter timings.
It’s currently written in mixed C and assembly.
In addition to synthesized video, Bailey also loves old vector arcade games. These are games where the CRT (cathode ray tube) is not a raster unit like in your old analog TV. A vector tube is more like an oscilloscope, where you draw lines at any angle. Todd wrote:
“As some of you may have known or been involved in, a couple buddies and I have been working on a new arcade game using old vector monitors to take advantage of how beautiful and alien they look. We built an FPGA-based vector generator, a high-bandwidth and resolution XYZ DAC/amp and have gotten really intimate with the guts of the Electohome G05 monitor.”
“Anyway, most of the hardware and engine stuff is done and we decided it was time to show it off to our friends. The storyboard as it stands is about cryogenically frozen Soviet pilots descending from space and blowing up Chicago, although the prototype game right now is just about blasting polygons. It’s in full 3D wireframe, and it also features a separately-driven monochrome ATM CRT as the ship’s HUD. We’d like it to become a proper stand up arcade game pretty soon but have basically no idea what to do with it when we’re done.”
I got into vector CRTs when I saw the schematics for the HV (high voltage) section of the Tempest vector monitor. They would have been better off running open-loop. What the flyback circuit does is try to maintain voltage on a system with a static load, so all you really get is excessive current as the flyback windings start to short, and the well-known smoke effect from these systems. A universal input current-mode flyback would be just the ticket– protecting the transformer from fire and I bet even that could run open-loop once you set it at the factory.