DigiTekXplorer - Pico VGA Encoder

In this project we demonstrate the amazing capabilities of the Raspberry Pi Pico.

In the 1940’s RS-170 was the main video standard used in the US. The standard defined an analog, composite signal that included both timing and video data.   Over the following decades, video standards were enhanced to add color.

Video Graphics Array (VGA) is a video standard introduced by IBM in 1987. In this standard, timing and data signals are placed on different electrical lines. The standard defines 5 main signals plus ground:

· 2 control signals: Horizonal and Vertical Sync, 

· 3 color, data signals: Red, Green, and Blue.

VGA timing signals resemble the timing signals from the older video standards but the signals are separated into Hsync and Vsync. The color information is also place on 3 separate signals: RGB.

Finally, in 2009 TV broadcasting companies were required to transition from analog video signals to an all-digital system. VGA is an old video standard that has been replaced by higher-definition digital standards like HDMI. However, there are still many monitors that include a VGA connection so it is fun and useful to develop a VGA project with the Raspberry Pi Pico to learn about video standard and learn about the Pico’s capabilities.

This is one of many projects created by Hunter Adams who is an instructor at Cornell University. Links to code and a detailed explanation of the VGA standard are shown below.

Hunter Adams; Cornell University

https://vanhunteradams.com

Cornell ECE 4760 (using Raspberry Pi Pico; RP2040)

https://ece4760.github.io

Pico: VGA Project

https://vanhunteradams.com/Pico/VGA/VGA.html

The Pico uses a Programmable Input Output (or PIO) feature and Direct Memory Access (or DMA) to interface to the VGA monitor.  The PIO is a powerful resource used to connect to external devices, such as the VGA monitor, with very little help from the Pico’s ARM processors.

In these projects, the PIO generates 2 VGA timing signals, Vsync and Hsync, and 3 color signals, RGB. During initialization, one of the ARM processors, inside the Pico, sets up a video buffer that can be continuously updated. The ARM processor also sets up 2 DMA channels to send video data (RGB) to the PIO which then sends the RGB data to the VGA monitor.

These projects show two of the useful and very powerful features of the Pico – DMA channels and PIO..

A YouTube link to a video showing the pattern generated by the Pico is provide below.