Interesting VGA hacks

Let’s continue the VGA theme I started in VGA memories and future posting. Here are some VGA hacking ideas on using VGA graphics adapter for non-traditional uses.

VGA connectors and cables carry analog component RGBHV (red, green, blue, horizontal sync, vertical sync) video signals, and VESA Display Data Channel (VESA DDC) data. Those analog component RGBHV lines are driven by very high speed digital-to-analog converters, so with some hacking VGA card can be used to generate all kinds of analogue signals (as long at the short pauses during HSYNC and VSYNC times do no matter in the application). Also the signals on the VESA Display Data Channel (VESA DDC) can be used to special applications.

Here are some interesting VGA hacking links:

I2C From Your VGA Port article tells that  VGA, DVI, and HDMI ports use Display Data Channel (DDC) to communicate with connected displays. This allows displays to be plug and play. However, DDC is based on I2C, which is used in all kinds of electronics. If you build a VGA to I2C breakout, convinces the kernel it’s a standard I2C device and use  i2c-tools to interact with the port.

Driving WS2811 LEDs with…VGA? shows an interesting way to  drive WS2811/2812 “Neopixel” LEDs: : hacking a computer’s VGA output to drive 500 WS2811s in a string. It turns out that you can send digital data that the Neopixels needed by carefully selecting a resolution and clock rate for the VGA to match the timings that the WS2811 modules wanted: A resolution of 840×1000 at 28MHz produces 70 pixels per WS2811 bit, or 12 bits per line. There are some further tricks that are needed, including circuit to fixing the voltage levels from 0.7V signal. Check the example video for WS2811 christmas lighting using VGA.

VGA – Vector Graphics Adapter brings back memories to time when early computers and arcade games used vector graphics displays. This little project combines a modern PC with a 1973 analog oscilloscope in X/Y mode to draw vector graphics. The usual way of doing that is the PC sound card, but a better way is using the VGA output. Combined with a modified video player it can output realtime vector graphics animations. Even the live capture or screen content can be shown as pseudo-vector graphics.There’s an OpenCV-based project that can play videos or stream webcam video to a scope using the VGA output.


Create DVB-T RF with your VGA card: Analog and Digital TV (DVB-T) Signal Generation article shows that PC running Linux and a recent VGA card, you can emit a real digital TV signal in the VHF band to your DVB-T set-top box. So this is essentially a VGA-based DVB-T modulator. Examples to transmit PAL or SECAM analog signals directly to your TV are also presented. All this is made possible because every VGA card contains high speed Digital to Analog Converters (DACs), and VGA DACs generate a lot of harmonics.

When hacking with VGA, sometimes you can get problems when plugging other than normal monitor to PC. A VGA dummy plug is a simple hack to fool the GPU and Windows by let them thinking there is a monitor plugged on a card. (VGA Hack) How To Make a VGA Dummy Plug article tells how you can make such adapter.



Be the first to post a comment.

Leave a Comment

Your email address will not be published. Required fields are marked *