VGA generation

2 Articles

Picture of a monitor with a fake "ransomware" banner on it, and a PC with the ESP32 VGA devboard mounted into it in the foreground

ESP32 Pretends To Be GPU; Gives You A Ransomware Scare

December 30, 2021 by 27 Comments

Sometimes a piece of hardware meets a prank idea, and that’s how the fun Hackaday articles are born. [AnotherMaker] shows us some harmless entertainment at the expense of an IT enthusiast in your life – programming an ESP32-powered devboard with a VGA output to show an ever-feared “all your files are encrypted” screen on a monitor connected to it. The ASCII text in its 8-bit glory helps sell this prank, making it look exactly like a BIOS-hijacking piece of malware it claims to be; akin to UIs of the past that skilled hackers would whip up in x86 assembly. The devboard’s integration into a PCI card backplate is a cherry on top, a way to seamlessly integrate this into a PC case, making it look not particularly different from an old graphics card. In such a configuration, we don’t doubt that this would be a head-scratcher to a certain kind of an IT department worker.

If you already have someone in mind as a target for this prank, you’re in luck, since [AnotherMaker] has shared his source code, too, and all you need is a ESP32 with a VGA port set up. You can get the same devboard, or you can even solder it all together with an ESP32 breakout and resistors, if you’re on a time or money budget, since the schematics for the LilyGO devboard are public. Not all devboards gets such a fun application, but it’s always fun to see when someone thinks of one – a perfect prank scenario that calls for a very specific devboard.

Wondering how it’s even possible to output VGA from the ESP32? We’ve covered this in the past – like this R&D project done by [bitluni], who then went ahead and expanded on it by connecting six displays at once. If you’ve connected your ESP32 to a VGA port and ran some test sketches, a UI library will help you upgrade your idea into a ready project in no time.

Continue reading “ESP32 Pretends To Be GPU; Gives You A Ransomware Scare” →

VGA Without A Microcontroller

March 7, 2017 by 47 Comments

One of the most challenging projects you could ever do with an 8-bit microcontroller is generating VGA signals. Sending pixels to a screen requires a lot of bandwidth, and despite thousands of hackers working for decades, generating VGA on an 8-bit microcontroller is rarely as good as a low-end video card from twenty years ago.

Instead of futzing around with microcontrollers, [Marcel] had a better idea: why not skip the microcontroller entirely? He’s generating VGA frames from standard logic chips and big ‘ol EEPROMs. It works, and it looks good, too.

VGA signals are just lines and frames, with RGB pixel values stuffed in between horizontal sync pulses, and frames stuffed between vertical sync pulses. If you already know what you want to display, all you have to do is pump the right bits out through a VGA connector fast enough. [Marcel] is doing this by saving images on two parallel EEPROMs, sending the output through a buffer, through a simple resistor DAC, and out through a VGA connector. The timing is handled by a few 74-series four-bit counters, and the clock is a standard 25.175 MHz crystal.

There’s not much to this build, and the entire circuit was assembled on a breadboard. Still, with the clever application of Python to generate the contents of the ROM, [Marcel] was able to build something that displays eight separate images without using a microcontroller.