Clem Mayer’s Customized SBC Comprises an ESP32 CPU and Raspberry Pi Pico GPU

A story of two processing models

From mid-tier microprocessors to smartphones and even a $5,000 gaming rig, the overwhelming majority of at the moment’s computer systems include two major varieties of processing models for dealing with the computational calls for of recent functions. Whereas a central processing unit (CPU) is supposed for extra generalized, sequential duties, a graphics processing unit (GPU) handles the rendering and output of graphics to a show, amongst different extremely parallel duties.

And over the past a number of months, Clem Mayer from element14 Presents has launched into a journey to create his personal single-board pc (SBC) with cheap parts whereas nonetheless being able to run Linux, drive a show, and talk to an exterior host. His design leverages an ESP32-S3 because the CPU and an RP2040-based Raspberry Pi Pico because the GPU – full with an I2C interconnect for sending graphics instructions to the Pico from Linux working on the ESP32.

The brand new PCB

Earlier than they have been mixed, each the ESP32-S3 Linux venture and the Raspberry Pi Pico GPU venture have been on their very own, particular person boards, which means {that a} new PCB design was in-order. The most recent revision options energy administration circuitry in addition to an HDMI connector on one facet, the ESP32 and Pico within the middle, and a 40-pin Raspberry Pi GPIO header close to the highest. And identical to the Pico GPU from earlier than, this whole board can match right into a PCIe slot and talk with a bunch over I2C. A SATA energy connector was additionally included throughout from the show output, however the element’s incorrect orientation left it unusable.

Points with I2C

Because of his improved flash software, loading Linux onto the ESP32-S3 was a lot simpler than the earlier model. However when it was time to ship I2C knowledge to the Pico, Mayer encountered a pair issues. First, the ESP32’s Linux kernel did not have a working I2C module, which led him to aim the identical I2C experiment on a Raspberry Pi 4. Nonetheless, the Pico was nonetheless not being detected by the OS, thus indicating a problem with both the driving force or its connection to the Pi.

Sending textual content from a terminal

As soon as Mayer had deemed his I2C quickly unusable, he rapidly pivoted to another mode of communication: USB/UART serial. The replace concerned permitting the Pico to just accept and interpret incoming textual content as a graphical textual content show command, thus permitting the Pico GPU to ship a stream of characters over DVI to a show. One Python script later and Mayer may now SSH into the Pi 4, run the serial communication program, and begin sending textual content to the Pico and subsequently the DVI output too.

Subsequent steps

With this proof-of-concept now purposeful, Mayer plans on pivoting his focus again to the Pico GPU and making it much more feature-rich. Some concepts embody a correct framebuffer, an expanded set of graphical instructions, and correct PCIe assist to be used in a wider vary of techniques. You may see how Mayer created this DIY single-board pc right here on the element14 Presents YouTube channel.