Confronted with a monitor that would display neither HDMI signal, nor composite video, [Joonas Pihlajamaa] took on a rather unorthodox task of getting his oscilloscope to work as a composite video adapter. He’s using a PicoScope 2204 but any hardware that connects to a computer and has a C API should work. The trick is in how his code uses the API to interpret the signal.
The first thing to do is make sure the voltage levels used in the composite signal are within the tolerances of your scope. [Joonas] used his multimeter to measure the center pole of the RCA connector and found that the Raspberry Pi board puts out from 200 mV to 2V, well within the PicoScope’s specs. Next he started to analyze the signal. The horizontal sync is easy to find, and he ignored the color information — opting for a monochrome output to ease the coding process. The next big piece of the puzzle is to ascertain the vertical sync so that he knows where each frame starts. He got it working and made one last improvement to handle interlacing.
The proof of concept video after the break shows off the he did. It’s a bit fuzzy but that’s how composite video looks normally.
Continue reading “Using an oscilloscope as a composite video adapter”
Here’s two builds that print text to a TV with only two pins:
Still Alive with an Arduino
After seeing all the builds that play Still Alive, [Bob] decided to take a 1972 amber monitor and recreate the cut scene at the end of Portal. The build uses the TVout library for Arduino. There were a few problems with running the Unix and Still Alive animations at the same time, so [Bob] flips a bit in the EEPROM at the end of the command line animation and restarts into GLaDOS’ report. You can check out the old school color monitor here
ATMega Video Text Generator
[Stian] didn’t think his build was good enough for Hackaday, but his friend [Mikael] thought otherwise. [Stian] wrote a library to generate an NTSC video signal in real time. It’s a text-based build with 37×17 character resolution and only requires about 3kB of RAM. As a bonus, it only takes up two pins on [Stian]’s ATMega128.
You can check out the videos for both these builds after the break.
Continue reading “Controlling a TV with a microcontroller”
[David Cranor], along with [Max Lobovsky’s] help, managed to build a thin client that uses an NTSC television as a monitor for only $6. This is his first foray into the world of ARM architecture and he has vowed to never use an AVR again. The powerful little chip uses timers to manage sync and DMA to transfer the full 480×240 frame buffer to the screen. Overclocked at 80 MHz there’s a lot of potential in this little board and he plans to take on the challenge of a full-color display for his next trick.
OpenStomp’s Coyote-1 is now available for $349. The guitar effects pedal lets users design and upload their own effects to the device. It has two stomp switches with LEDs, an LCD display, and four user assignable knobs. The back has 1/4″ in/out and one selectable 1/4″. It also features NTSC composite out, a headphone jack, mini-USB for uploading, and an RJ11 I2C bus for expansion. The processor is a Parallax Propeller Chip. While the OS on the pedal is open source, the hardware design and effect design software are not. You can check out the source and product manual on their forum. If you’re more interested in breadboarding hardware, you might like the Beavis Board we covered earlier.
[via Create Digital Music]