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  • Author Author: tariq.ahmad
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Turning a Raspberry Pi Pico into a GPU! -- Episode-644

In this episode, Clem takes us through the intricacies of the Raspberry Pi Pico and graphics cards. Forget the technical jargon; imagine a graphics card as a translator between your CPU and the screen, a bit like those old-school graphics adapters but with a modern twist. Clem, our guide, dives into the world of microcontrollers, specifically the RP2040, cooking up digital concoctions for today's monitors and touchscreens. 

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Downloads & Links | Bill of Material | Discussion

But every journey has its bumps, and Clem hits a roadblock with high-speed video signals. Ever tried hand wiring on a breadboard? It can be a hit or a miss. Spoiler: It's a miss. Clem troubleshoots with DVI-Socks, dealing with impedance-matching intricacies using resistors. It's a bit like walking a tightrope – precision is key, but it's easy to slip. 

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The video navigates through connection experiments – soldering DVI sockets, trying headers – with Clem emphasizing the importance of stable connections over detachable boards. A nudge in the wrong direction, and the signal's out of sync. Clem wraps it up neatly with a PCB design, a more reliable solution for video signals with the Raspberry Pi Pico. 

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The plot thickens as Clem tackles the connection conundrum.  In the PCIe connector, Clem spots a hidden SMBus, an I2C bus in disguise.  This lets Clem attach the Pseudo-GPU to the SMBus via the PCI connector. 

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The grand finale showcases Clem's Arduino code, a practical display of text, colour, and rotation using the Adafruit GFX library. Clem demonstrates using two Raspberry Pi Pico boards, connected via I2C, showing them playing nicely with a small monitor. The graphics are very basic, but the concept opens doors for more creative projects. 

Downloads & Links:

Bonus Content Video:

Bill of Material:

Product Name Manufacturer Quantity Buy Kit
Raspberry pi pico Raspberry pi 2 Buy Now
 

Additional Parts:

DVI Socket

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  • Nice project. There are several use cases where you only need a microcontroller but you need to drive a larger display for basic text and graphics.

    The +5V originally was to power the EEPROM containing the EDID data so as the source can read the data even if the sink (display) is powered off.

    Sinks can also return +5V as a hot plug detect signal so that the source knows that there is an active display connected.

    The supply is supposed to be current limited to protect against shorts. Later versions of HDMI have since uprated this from around 50mA to 300mA in order to support 'HDMI Cable Power' which is used for powering longer active cables.

  • in reply to beacon_dave

    that makes sense, likely some displays may detect themselfes when they are plugged in via the 5V lines. could be the reason some displays work and others don't is that simple mechanism

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