ESP32 Becomes Music Player In Under 40 Lines Of Code

The demo code for [XTronical]’s ESP32-based SD card music player is not even 40 lines long, though it will also require a few economical parts before it all works. Nevertheless, making a microcontroller play MP3s (and other formats) from an SD card is considerably simpler today than it was years ago.

Part of what makes this all work is I2S (Inter-IC Sound), a format for communicating PCM audio data between devices. Besides the ESP32, at the heart of it all is an SD card reader breakout board and the MAX98357A, which can be thought of as a combination I2S decoder and Class D amplifier. The ESP32 reads audio files from the SD card and uses an I2S audio library to send the I2S data stream to the MAX98357A (or two of them for stereo.) From there it is decoded automatically and audio gets pumped though attached speakers.

A few economical components, and only a handful of connections between them.

It’s amazing how much easier audio is to work with when one can take advantage of shuffling audio data around digitally, and the decoder handles multiple formats with an amplifier built in. You can see [XTronical]’s ESP32 player in action in the video embedded below.

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Under The Hood Of Second Reality, PC Demoscene Landmark

In 1993, IBM PCs & clones were a significant but not dominant fraction of the home computer market. They were saddled with the stigma of boring business machines. Lacking Apple Macintosh’s polish, unable to match Apple II’s software library, and missing Commodore’s audio/visual capabilities. The Amiga was the default platform of choice for impressive demos, but some demoscene hackers saw the PC’s potential to blow some minds. [Future Crew] was such a team, and their Second Reality accomplished exactly that. People who remember and interested in a trip back in time should take [Fabien Sanglard]’s tour of Second Reality source code.

We recently covered another impressive PC demo executed in just 256 bytes, for which several commenters were thankful the author shared how it was done. Source for demos aren’t necessarily released: the primary objective being to put on a show, and some authors want to keep a few tricks secret. [Future Crew] didn’t release source for Second Reality until 20th anniversary of its premiere, by which time it was difficult to run on a modern PC. Technically it is supported by DOSBox but rife with glitches, as Second Reality uses so many nonstandard tricks. The easiest way to revisit nostalgia is via video captures posted to YouTube (one embedded below the break.)

A PC from 1993 is primitive by modern standards. It was well before the age of GPUs. In fact before any floating point hardware was commonplace: Intel’s 80387 math co-processor was a separate add-on to the 80386 CPU. With the kind of hardware at our disposal today it can be hard to understand what a technical achievement Second Reality was. But PC users of the time understood, sharing it and dropping jaws well beyond the demoscene community. Its spread was as close to “going viral” as possible when “high speed data” was anything faster than 2400 baud.

Many members of [Future Crew] went on to make impact elsewhere in the industry, and their influence spread far and wide. But PC graphics wasn’t done blowing minds in 1993 just yet… December 10th of that year would see the public shareware release of a little thing called Doom.

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A Jaw-Dropping Demo In Only 256 Bytes

“Revision” is probably the Olympics of the demoscene. The world’s best tiny graphics coders assemble, show off their works, and learn new tricks to pack as much awesome into as few bytes as possible or make unheard-of effects on limited hardware. And of course, there’s a competition. Winning this year’s 256-byte (byte!) competition, and then taking the overall crowd favorite award, was [HellMood]’s Memories.

If you watch it in the live-stream from Revision, you’ll hear the crowd going (virtually) wild, and the announcer losing his grip and gasping for words. It’s that amazing. Not only are more effects put into 28 bytes than we thought possible, but there’s a full generative MIDI score to go with it. What?!?

But almost as amazing is [HellMood]’s generous writeup of how he pulled it off. If you’re at all interested in demos, minimal graphics effects, or just plain old sweet hacks, you have your weekend’s reading laid out for you. [HellMood] has all of his references and influences linked in as well. You’re about to go down a very deep rabbit hole.

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LIDAR Built On Familiar Platform

Moore’s law may have reached its physical limit for transistor density, but plenty of other technologies are still on that familiar path of getting smaller and smaller as time passes. It looks like LIDAR is no exception to this trend either. This project from [Owen] shows a fully-functional LIDAR system for about $20 and built almost entirely on top of an ESP32.

The build uses a Time-Of-Flight IR laser range sensor controlled by the ESP32, and the sensor is much smaller than even the ESP32’s footprint so it takes up very little extra space. To get it to function as a LIDAR system instead of just a simple rangefinder it does need a motor in order to rotate itself to see its entire space. Besides its small form factor and low cost, it also has a handy user interface that can run anywhere an HTML5 browser can run, making the use of the system easy and straightforward as well. All of the code is available on the project’s GitHub page.

We wouldn’t expect a system like this to be driving an autonomous car anytime soon, it’s update rate is far too slow, but its intent for small robots and even as an educational demo for learning LIDAR is second to none. If you do need a little more power in a LIDAR system but still don’t want to break the bank, we featured this impressive setup a few weeks ago.

Get Compressed Air From Falling Water With The Trompe

If you’re like us, understanding the processes and methods of the early Industrial Revolution involved some hand waving. Take the blast furnace, which relies on a steady supply of compressed air to stoke the fire and supply the oxygen needed to smelt iron from ore. How exactly was air compressed before electricity? We assumed it would have been from a set of bellows powered by a water wheel, and of course that method was used, but it turns out there’s another way to get compressed air from water: the trompe.

As [Grady] from Practical Engineering explains in the short video below, the trompe was a clever device used to create a steady supply of high-pressure compressed air. To demonstrate the process, he breaks out his seemingly inexhaustible supply of clear acrylic piping to build a small trompe. The idea is to use water falling around a series of tubes to create a partial vacuum and entrain air bubbles. The bubbles are pulled down a vertical tube by the turbulence of the water, and then enter a horizontal section where the flow evens out. The bubbles rise to the top of the horizontal tube where they are tapped off by another vertical tube, as the degassed water continues into a second vertical section, the height of which determines the pressure of the stored air. It’s ingenious, requiring no power and no moving parts, and scales up well – [Grady] relates a story about one trompe that provided compressed air commercially for mines in Canada.

Need an electricity-free way to pump water instead of air? Check out this hydraulic ram pump that takes its power from the water it pumps.

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Full Motion Video And 3D Graphics Make This Genesis Demo Pop

The SEGA Genesis (aka Mega Drive) was launched at the tail end of the 1980s, bringing a new level of performance to the console world. At the time, 2D graphics ruled the roost, outside a few niche titles here and there. Decades later however, the demoscene continues to work in earnest. The Red Eyes demo is a great example of what can be done when pushing the Genesis hardware to the limits.

The demo features full motion video and an impressive 3D sequence. It’s quite a feat to pull this off with the limited resources of the Genesis platform. [Remute], [Kabuto] and [Exocet] have laid their secrets bare in a technical document, describing in explicit detail how it’s all achieved.

There’s plenty of juicy reading material here. There are palette hacks to produce high-quality greyscale images, rendering tips to produce the smooth 3D rendered sequences, as well as optimizations to create the best possible sample playback using the onboard YM2612 sound chip. It’s a tour de force of development, and it’s astounding to look behind the curtain to see just what can be achieved.

If you’re thinking about tinkering with the Genesis yourself, you might find it useful to have a dev kit on your bench. Video after the break.

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The Mother Of All Demos, 50 Years On

If you’re like me, chances are pretty good that you’ve been taught that all the elements of the modern computer user interface — programs running in windows, menus, icons, WYSIWYG editing of text documents, and of course, the venerable computer mouse — descended from the hallowed halls of the Xerox Corporation’s Palo Alto Research Center in the early 1970s. And it’s certainly true that PARC developed these technologies and more, including the laser printer and object-oriented programming, all of which would grace first the workplaces of the world and later the homes of everyday people.

But none of these technologies would have existed without first having been conceived of by a man with a singular vision of computing. Douglas Engelbart pictured a future in which computers were tools to sharpen the human intellectual edge needed to solve the world’s problem, and he set out to invent systems to allow that. Reading a Twitter feed or scanning YouTube comments, one can argue with how well Engelbart’s vision worked out, but there’s no arguing with the fact that he invented almost all the trappings of modern human-computer interaction, and bestowed it upon the world in one massive demonstration that became known as “The Mother of All Demos.”

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