Learn How to Get VGA Video Output From a Raspberry Pi Pico

Most devices today have digital video output, such as HDMI or DVI. Digital video takes a relatively high amount of processing power to generate, but it is more straightforward since you’re dealing entirely with bits and bytes. Digital video also usually has a higher resolution than analog video. But analog video is still useful, particularly if you’re working with older displays that do not accept digital video input. Unfortunately, it can be tricky to generate analog video with microcontrollers, because the timing has to be very precise. It is, however, possible to generate a VGA video signal using a Raspberry Pi Pico and Robin Grosset has a video explaining how to do so.

VGA (Video Graphics Array) used to be very common for computer monitors when composite video was outdated and couldn’t support high resolutions, but digital video standards were still being developed. A VGA connection has signals for red, green, blue, horizontal sync, and vertical sync. Those sync signals are what makes it difficult to generate VGA video, because the timing has to be exact. With digital video, you can generally send data as quickly as you’re capable of and that data can be buffered as necessary. That isn’t the case with analog video like VGA, which requires that the signals be sent at the exact timing to create the image on a display.

This is why the Raspberry Pi Pico can handle VGA output, because it has a speed dual-core Arm Cortex-M0 processor running at 133MHz. That’s enough to generate all of the VGA signals properly and to actually process the content to be displayed. You need surprisingly little hardware to achieve this. All you need is the Raspberry Pi Pico itself, a VGA connector, an assortment of resistors, and some jumper wires. Grosset goes into detail explaining why the resistors are necessary, what their values should be, and how to connect them. They form a resistor ladder to create a 5-bit DAC (Digital-to-Analog Converter) to produce the RGB signals, which results in 32,768 possible colors. To test the video output, you can use demos that are in the Pico-Extras folder supplied by Raspberry Pi themselves. How you choose to utilize the VGA output is completely up to you, but it is really cool to see a $4 development board that can generate relatively high-quality analog video.