Grading Tomatoes With An ESP32 And ML

August 8, 2026 by 6 Comments

If you’ve ever worked with produce, you might know about grading. In addition to deciding if, say, a strawberry is good or not, they also have to sort them by color. Turns out, you don’t care if one package of berries is a bit redder than another, but you do care if one package has too much color variation. [Pmalfa31] applied an ESP32 and machine learning to grading tomatoes.

The system knows in advance if you are processing standard tomatoes or cherry tomatoes and uses two different sets of learned data depending on which you select. The program receives raw data from an optical sensor and then processes it to remove empty belt images, compute statistical information, and group readings for a single fruit together.

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Easy Theremin Uses ESP32

August 2, 2026 by 6 Comments

The Theremin is that classic electronic musical instrument that makes those weeee-ohhhhh noises which were so popular in mid-century science fiction movies. Mid-last-century, that is, because this century is just beginning. In any case, you could build one with old-school analog electronics, or you could go a more modern route, as [ericCycles] did.

The build relies almost entirely on an ESP32 microcontroller with minimal supporting circuitry. Like any other Theremin, pitch and volume are controlled by moving hands closer or farther away from two antenna. In this case, the ESP32 uses its capacitive touch circuitry to detect effectively detect hand proximity to the two antenna in question, and uses those values to control the pitch and volume of a synthesized waveform. That waveform is then pumped out over the onboard digital-to-analog converter for playback on external speakers.

If you want to build a simple Theremin-like instrument quickly and easily, it’s hard to beat the simplicity on offer here. We’ve featured some other fun variants over the years, too, like this version that uses time-of-flight sensors for the human interface.

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A Capable KVM Built With The ESP32

July 30, 2026 by 17 Comments

[Evgenij Spitsyn] spotted a KVM build on these very pages some time ago. That inspired their own build, leveraging the versatility of the ESP32-P4 microcontroller.

The concept is straightforward. Named the ESPKVM, the device is designed to hook up to a computer’s HDMI and USB ports. It captures the video output, while presenting itself as a standard keyboard and mouse device. In this way, it allows remote control of the machine over IP. It achieves this feat with the aid of the Toshiba TC358743 HDMI-to-CSI bridge, which is essentially the video capture hardware of the build.

The video output of the machine is streamed in MJPEG or H.264 format. The device is capable of serving up storage from a micro SD card or the onboard flash, as well as handling things like power/reset control and wake-on-LAN. All in all, it’s a very complete package, and full of useful features. Just don’t use it over the public internet yet — [Evgenij] notes it hasn’t been reviewed for potential security holes yet, even though it has some basic authentication features baked in.

If you’ve got an ESP32-P4 ready to go with a TC358743 HDMI bridge, you can actually head over to the ESPKVM website and flash the code right in your browser to get going. Meanwhile, if you found this build interesting, you might like to scope out the one that inspired it. If you’re cooking up similar utility hacks, be sure to notify the Hackaday tipsline.

The ESP32 Gets A Web Browser

July 29, 2026 by 33 Comments

At the Hackaday Europe conference in Italy earlier in the year, we were shown a rather interesting device. The work of [Alun Morris], it was an ESP32-powered Cheap Black Display board, and it was running a web browser. Definitely an achievement.

Lest you imagine that it was sporting the latest and greatest in browser technology, we must disappoint you. The browser in question is a very basic text mode device, but it did happily retrieve Hackaday, which should be the only test a browser should need to pass.

Under the hood it’s running FreeRTOS, with separate HTML retrieval and tokenizing, and UI processes. It can fetch web pages directly, but there’s also a server-side proxy for difficult sites, and for creating image thumbnails.

An ESP32 is a powerful microcontroller, but it’s fair to say it’s not in the league of running a web browser and as far as we can remember this is the first one we’ve seen. We’re sure it’s a field with further progress to be made though, particularly with the more powerful recent chips in the series. This project however is a good start, and more importantly it can be yours for a few dollars on Ali to buy a dev board. What are you waiting for?

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60 FPS NES Emulator On ESP32

July 22, 2026 by 10 Comments

At least in theory, video games are more resistant to becoming lost media thanks to their digital nature — they’re easy to copy and emulators have saved many titles that are otherwise locked in corporate vaults. But emulators give us something beyond simple preservation: they can also be used to enhance games well beyond the capabilities of the original systems while still preserving the souls of the games, as this NES emulator manages to do.

The emulator is called Anemoia-ESP32, and as its name suggests is a re-write of the Anemoia emulator specifically built for the ESP32. By modern standards these little chips don’t pack much of a punch, but compared to original NES hardware they’re more than up to the task of gaming. This project aims to recreate the Nintendo Entertainment System experience as faithfully as possible, hitting 60 FPS in most instances, as well as maintaining full audio emulation. Running on an ESP32 enables some truly small handheld options that would be difficult to achieve with more traditional platforms for emulation. There are some PCBs available here as well, but aren’t required to explore this project with.

As far as extra features compared to original NES hardware, the emulator does support save states and has a number of other settings improvements. Installation is as easy as flashing any other firmware image onto an ESP32, which these days can even be done from the browser. No word on whether or not it will eventually support emulating dual Picture Processing Units, but we can hope.

ESP32-driven Roulette Wheel Could Have Used A 555, But That Didn’t Have WiFi

July 18, 2026 by 5 Comments

Sometimes you see a project and immediately, before going into the details, your mind throws up the old refrain: “coulda used a 555” — well, [Hulk] actually agrees when it comes to his ESP32-based, 3D printed roulette wheel. The first version did use a 555, but then feature creep kicked in and the final project ended up with an ESP32 instead. We’ve all been there.

The roulette wheel circuit is retained from the 555 version, with the ESP32 providing clock pulses instead of the venerable oscillator chip — it uses a pair of decade counters to create the chase effect of the LED around the wheel. With a handsome printed enclosure, [Hulk] could have stopped there, but then he’d have to keep track of scoring and the like manually like some kind of dark age peasant. It’s the 21st century, we have computers to to that for us!

Now, even though the ESP32 is still driving the LED chase via the decade counters, it can keep track of where the “ball” of light lands, and reports that via WiFi or serial. While it would have been an option to run the whole game on the ESP32. [Hulk] just has those values put into an SQL database on a server, which also runs the game front-end via PHP. The resulting web page lets two players make their bets and track their wins and losses over time. You can see that in action in the video embedded below.

Overkill? Sure, but we suspect [Hulk] already had the equipment and experience to make this the fastest way to get a playable game. There are easy ways to serve web content from an ESP32, but the easiest tool to use is always the one in your back pocket, right?

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Get Your ESP32 Sunny Side Up With This Solar Dev Board

July 13, 2026 by 15 Comments

There are a lot of ESP32-based development boards out there– and why not? It’s a versatile chip that can be used in all sorts of situations, and people want boards to match them. Not finding one to his liking that was specifically built for solar powered IoT projects, [Narrow Studios] rolled his own. Well, designed it; like most these days, he’s outsourced the manufacturing to PCBWay, which is where you’ll need to go if you want one.

Why might you want one? Well, if you have similar goals in mind to [Narrow Studios]. He’s put an ESP32-C6 Mini on the board, which means it’s got most of the IoT communications protocols you might be interested in — bluetooth, wifi, Matter, Thread, and Zigbee, too. Ten 10 IO pins have been broken out, plus I2C on a QWIIC connector, which gets you a whole ecosystem of sensors to easily plug into. The “solar” part is justified by the inclusion of a BQ25186 linear battery charging IC from Texas Instruments, with the designated solar power input protected against reverse voltage in case you– like this author– have let magic smoke out by hooking things up backwards. Is it embarrassing? Yes. Does it happen? Also yes, so putting protection on the board is a nice feature. [Narrow Studios] released a video that we’ve embedded below discussing his design choices and demonstrating the device, but the project page can give you the gist.

Of course there’ve been plenty of solar-powered projects to feature the ESP32 here before– you can even use it for maximum power point tracking— but this dev board might be exactly what someone is looking for to build their next IoT project, so we’re thankful to [Narrow Studios] for the tip.

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