The number of hours we spend staring at screens is probably best unknown, but how about the technology that makes up the video on the screen? We’ve all seen a reel-to-reel projector on TV or in a movie or maybe you’re old enough to have owned one, surely some of you still have one tucked away real nice. Whether you had the pleasure of operating a projector or just watched it happen in the movies the concept is pretty straight forward. A long piece of film which contains many individual frames pass in front of a high intensity lamp while the shutter hides the film movement from our eyes and our brain draws in the imaginary motion from frame to frame. Staring at a Blu-ray player won’t offer the same intuition, while we won’t get into what must the painful detail of decoding video from a Blu-ray Disc we will look into a few video standards, and how we hack them.
It’s not uncommon to bitbang a protocol with a microcontroller in a pinch. I2C is frequently crunched from scratch, same with simple serial protocols, occasionally complex systems like Ethernet, and a whole host of other communication standards. But VGA gets pretty tricky because of the timing requirements, so it’s less common to bitbang. [Sven] completely threw caution to the wind. He didn’t just bitbang VGA on an Arduino, but he went one step further and configured an array of 7400 logic chips to output a VGA signal.
[Sven]’s project is in two parts. In part one, he discusses choosing a resolution and setting up the timing signal. He proceeds to output a simple(-ish) VGA signal that can be displayed on a monitor using a single gate. At that point only a red image was displayed, but getting signal lock from the monitor is a great proof of concept and [Sven] moved on to more intricate display tricks.
With the next iteration of the project [Sven] talks about adding in more circuitry to handle things like frame counting, geometry, and color. The graphics that are displayed were planned out in a simulator first, then used to design the 7400 chip configuration for that particular graphic display. It made us chuckle that [Sven] reports his monitor managed to survive this latest project!
We don’t remember seeing non-programmable integrated circuits used for VGA generation before. But bitbanging the signal on an Arduino or from an SD card slot is a great test of your ability to calculate and implement precise timings with an embedded system. Give it a try!
Although graphical programming languages have been around for ages, they haven’t really seen much use outside of an educational setting. One of the few counterexamples of this is Pure Data, and Max MSP, visual programming languages that make music and video development as easy as dropping a few boxes down and drawing lines between them.
A few years ago, [Thomas] and [Danny] developed a very cool Pure Data audio-visual presentation. The program they developed only generated graphics, but though clever coding they were able to generate a few audio signals from whatever video was coming out of their computer. The project is called TVestroy, and it’s one of the coolest audio-visual presentations you’ll ever see.
The entire program is presented on three large screens and nine CRT televisions. With some extremely clever code and a black box of electronics, the video becomes the audio. Check it out below.
Although this is a relatively old build, [Thomas] thought it would be a good idea to revisit the project now. He’s open sourced most of the Pure Data files, and everything can be downloaded on the project page.
[Radical Brad] has played around with FPGAs, video signals, and already has a few astonishing projects of bitbanged VGA on his resume. Now he’s gone insane. He’s documenting a build over on the 6502.org forums of a computer with Amiga-quality graphics built out of nothing but a 65C02, a few SRAM chips, and a whole pile of logic chips.
The design goals for this project are to build a video game system with circa 1980 parts and graphics a decade ahead of its time. The video output is VGA, with 400×300 resolution, in glorious eight-bit color. The only chips in this project more complex than a shift register are a single 65c02 and a few (modern) 15ns SRAMs. it’s not a build that would have been possible in the early 80s, but the only thing preventing that would be the slow RAM chips of the era.
So far, [Radical] has built a GPU entirely out of 74-series logic that reads a portion of RAM and translates that to XY positions, colors, pixels, and VGA signals. There’s support for alpha channels and multiple sprites. The plan is to add sound hardware with support for four independent digital channels and 1 Megabyte of sample memory. It’s an amazingly ambitious project, and becomes even more impressive when you realize he’s doing all of this on solderless breadboards.
[Brad] will keep updating the thread on 6502.org until he’s done or dies trying. So far, it’s looking promising. He already has a bunch of Boing balls bouncing around a display. You can check out a video of that below.
The Intel Edison is out, and that means there’s someone out there trying to get a postage-stamp sized x86 machine running all those classic mid-90s games that just won’t work with modern hardware. The Edison isn’t the only tiny single board computer with an x86 processor out there; the legends told of another, and you can connect a graphics card to this one.
This build uses the 86Duino Zero, a single board computer stuffed into an Arduino form factor with a CPU that’s just about as capable as a Pentium II or III, loaded up with 128 MB of RAM, a PCI-e bus, and USB. It’s been a while since we’ve seen the 86Duino. We first saw it way back at the beginning of 2013, and since then, barring this build, nothing else has come up.
The 86Duino Zero only has a PCI-e x1 connector, but with an x16 adapter, this tiny board can drive an old nVidia GT230. A patch to the Coreboot image and a resistor for the Reset signal to the VGA was required, but other than that, it’s not terribly difficult to run old games on something the size of an Arduino and a significantly larger graphics card.
Thanks [Rasz] for sending this one in.
For last year’s Hackaday Prize, [PK] tried to build a video card for microcontrollers and headless Linux systems. It was only 640×480 resolution VGA, but the entire project was designed around a CPLD communicating with a microcontroller over SPI. This prize entry was, by [PK]’s own admission, a failure. It was late, but now he’s had an entire year to perfect his design. That means he can enter version two of his VGATonic in The Hackaday Prize.
The VGATonic version 2 uses a Xilinx XC95144XL CPLD for the VGA timing, and an ATTiny 2313a to read the SPI bus. Video memory is four megabits of static RAM. That’ls pretty much all you need for the most basic VGA graphics card, and all of this is packed onto a 3×3 inch PCB.
You can do a lot with 640×480 8-bit graphics running at 25FPS. In the video below, [PK] has a ‘hello world’ of sorts, Doom, running on a Raspberry Pi 2 with his SPI graphics card. Yes, it’s a graphics card for the Raspberry Pi, and it looks really good.
Further refinements of the design will include some primitive graphics routines. Not OpenGL or anything fancy, just something to reduce the number of writes on the SPI bus. It’s a great project, and perfect if you want to add video out to an Intel Galileo or other microcontroller project. [PK] has a video demo, you can check that out below.
The 2015 Hackaday Prize is sponsored by:
[Cliff] is pushing VGA video out of a microcontroller at 800×600 resolution and 60 frames per second. This microcontroller has no video hardware. Before we get to the technical overview, here’s the very impressive demo.
The microcontroller in question is the STM32F4, a fairly powerful ARM that we’ve seen a lot of use in some pretty interesting applications. We’ve seen 800×600 VGA on the STM32F4 before, with a circles and text demo and the Bitbox console. [Cliff]’s build is much more capable, though; he’s running 800×600 @ 60FPS with an underclocked CPU and most (90%) of the microcontroller’s resources free.
This isn’t just a demo, though; [Cliff] is writing up a complete tutorial for generating VGA on this chip. It begins with an introduction to pushing pixels, and soon he’ll have a walkthrough on timing and his rasterization framework.
Just because [Cliff] has gone through the trouble of putting together these tutorials doesn’t mean you can’t pull out an STM Discovery board and make your own microcontroller video hacks. [Cliff] has an entire library of for graphics to allow others to build snazzy video apps.