DIVINER: Occult Synth Firmware For The Cardputer

November 14, 2026 by Elliot Williams No comments

We see some strange software around these parts, but this is probably the strangest. DIVINER is a firmware for the M5 Cardputer, which is an interesting device in its own right, being essentially a tiny ESP32-S3 dev kit with an even tinier screen, keyboard, some GPIOs, I2C, and an audio jack for output. It is essentially a blank canvas that can do anything if you write the firmware for it.

And that’s what DIVINER does: a little of everything. It’s part standalone synthesizer and sequencer, taking advantage of the I2S audio out, part visualization engine, part WiFi and Bluetooth scanner and monitor (what?), with an LLM interface and an IR blaster thrown in for good measure. [voidrane Splicer] even explores the Channel-State Information to do presence detection, like we’ve seen recently elsewhere. Byte-beat player anyone?

The Hackaday.io page talks about the underlying system layer before it even gets to the applications, and we get the feeling that all of the different apps, called “rites”, were crammed in to exercise it and show off the “blood and ember”, Diablo-esque visual style. But that doesn’t stop us from enjoying the audio engine, demonstrated in the video below, or the awesome graphics.

Do these apps hang together more than visually? Do they need to? Is the sum of the parts so large that you don’t even worry about the whole? We don’t know, but it’s also got a simulator so you can try that out while your Cardputer is shipping.

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ESP32 Flight Tracker On Apple CRT

November 13, 2026 by Tyler August 7 Comments

Sometimes we’re most taken by what’s on the screen; sometimes the screen itself is the most interesting part of the project. In this case, it’s the latter. That’s no slight against [Virtual-Bet-4566], whose ESP32-based flight tracker looks very nice– but a big part of what it makes it so nice is that it’s displaying the ADS-B flight data on an old green-phosphor monitor from the Apple II days.

He’s using an ESP32-WROOM-32, which gives him both the wifi connection needed to grab aircraft locations and flight details– including photos of individual aircraft, when available from Planespotters.net– but crucially has an 8-bit digital-analong-converter that he’s using to drive the composite input on the old Apple monitor. Not all of the expansive ESP32 family have that feature, but at this point you might as well call ESP32 a brand of MCU than a family given the vast differences between them. Since composite video doesn’t need much power, he’s connected the dev board directly to the monitor. It’s that delicious combination of the old and new that really gets us vibing.

It can show you an image of the plane, but it’s not exactly high-def.

Speaking of vibing, yes, this whole thing was vibe-coded, as [Virtual-Bet] freely admits in the Reddit thread. LLMs seem to be really good at making these flight tracking apps, to judge from other posts on that site, but this one stands out for its display method. He’s also apparently got weather and his own local sensor data incorporated in the wifi-controlled display application, and isn’t interested in sharing the code since you could prompt it yourself. Fair enough.

We’ve seen composite-out from the ESP32 family before, more than once— which is probably how the LLM knew to pull it off–but there’s just something about that green glow.

Story via CircuitDigest.

Using Halftone Images In QR Codes Without Upsetting Scanners

November 6, 2026 by Maya Posch 6 Comments

Although quick-response (QR) codes are rather simple monochrome affairs, adding embellishments to them is a popular activity, if only to make QR codes not stick out like a sore thumb in e.g. flashy marketing flyers. The most simple approach here is to put any regular graphic in e.g. the center of said QR code and lean on the scanner’s error-correcting features to route around the damage, but a more sophisticated approach uses halftone images that are blended with the QR code, as first demonstrated in 2013 by [Hung-Kuo Chu] et al.

A number of online halftone image QR generators exist that use the methodology in said 2013 paper to allow you to generate any mesh-up you like. Here [Jorge C. Lucero] provides a JavaScript-based version written from scratch that can run client-side. According to [Jorge] this was a weekend’s project created out of sheer curiosity.

The basic way that this algorithm works is by using each of the data modules of the QR code as a 3×3 grid of submodules, using only the center sub-module as the module’s color. The other sub-modules are thus free to be assigned a halftone color grade that creates the final module’s appearance.

Although this should generally work without leaning on the scanner’s error-correction features, an ‘enhancement’ mode is possible that enhances the image clarity at the cost of introducing some scanning errors that will require correction. Overall it provides a pretty clear improvement over simple binary image embedding, especially when higher resolution QR codes are used.

Cheap FPGA Board Becomes Retro-Style Computer

November 1, 2026 by Zoe Skyforest 24 Comments

The Tang Nano 9K is a cheap FPGA development board that can usually be acquired for around $15 or so. [ThePartsBin] has been experimenting with this hardware and figured out how to set it up as a retro-style computer.

The board is based around the Gowin GW1NR-9C FPGA which only has 8,640 LUTs. However, that’s enough to spin up a 36 MHz RISC-V CPU, and there’s 8 MB of RAM on tap, along with HDMI, 48 kHz stereo audio output, two USB ports, and an SD card reader. Combine all that together, and you’ve got a machine capable of playing a whole raft of classic 1990s games.

[ThePartsBin] ported Doom, Tyrian, System Shock and Ultima VII, all of which run at a playable speed at a tasty 720 x 480 resolution. The writeup does a great job of explaining what it took to actually implement these classic games on the platform. Tons of compromises were made along the way, but that’s the engineering challenge, isn’t it?

If you’re looking to play retro games, this is not really the fastest or cheapest way to do it. You could probably just emulate them on the machine you’re using to read this very website. If you’re trying to get to grips with a new FPGA board for the first time, though, projects like this can be a very useful learning experience indeed.

A Game Engine For Microcontrollers

November 1, 2026 by Zoe Skyforest 22 Comments

If you wanted to make a game that ran on a commodity microcontroller, you could be forgiven for not knowing where to start. Never fear, for [Fedyfausto] has just the setup to help you in your quest.

It’s called Jet Studio, and it’s an open-source game editor that looks and works like Godot. In reality, it’s a Godot app with a C++ GDExtension, and it’s for making games that run on an Arduino Nano ESP32 or an STM32F746. Specifically, it’s intended for use with the commonly-available ILI9341 SPI LCD display.

The engine can be used for both 2D and 3D games with a handy level of performance. [Fedyfausto] notes that a 2D shooter runs at 62 FPS on the Nano ESP32 and 83 FPS on the STM32. Other fun demos include a partially-3D Outrun-style game, and a 3D physics simulation. They show just what the engine can do, and from there, it’s really up to your creativity for what you choose to make with it.

We see all kinds of games ported to the microcontroller world these days; you can even run Metal Gear Solid on an ESP32 if you really feel like it. What a world we live in. Video after the break.

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Simplifying Slide Rule Calculations With Trig

October 16, 2026 by Al Williams 12 Comments

[Bob the Science Guy] remembers how to use a slide rule. Even after all these years, it is pretty easy to remember how to multiply and divide. If you can’t remember, you can usually work it out, as long as you understand how slide rules work. But what about sine, cosine, and quadratics? [Bob’s] been making videos about topics like this, and if you’ve wanted to put your slide rule collection to practical use, you’ll enjoy these videos. You can see one below.

The trick to the slide rule is that it is deceptively simple. You are in effect adding logarithms and then taking an antilog. The issue is that you still have to have some intuition about the scale of the answer since 2×3 works out the same as 2×3000 or 200×300.

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What’s A Nonius?

October 14, 2026 by Al Williams 12 Comments

If you already know what a nonius is, you can probably skip this post. But, if like us, you would have to look it up, we’ll tell you what we found out. It turns out, a translation mistake taught us a new word and some history we weren’t aware of.

In the manual, this is captioned: Figure 4-7 Nonius Display (Standard Mode)

Have a look at the adjacent graphic from a waveform display. What would you call the vertical red lines at positions 139 and 200?

We’d probably call them markers. Or maybe cursors. The manual, however, calls each one a “nonius”. It refers to them that way multiple times.

Oddly, the manual also has sentences like “Select one nonius and right-click, and then select ‘Remove Marker’ in the next window to delete the nonius.”

So, clearly, a nonius is the vertical line marker or cursor. But that, of course, begs a question…

What is a Nonius?

Have you ever heard of the vernier scale? If you’ve done navigation, used a traditional caliper, or tuned an old shortwave receiver, you probably have. [Pierre Vernier] developed it in 1631 as a way to better interpolate values on a scale.

However, there was an earlier version used to improve measurements on astrolabes. A Portuguese navigator named [Pedro Nunes] created this type of astrolabe in 1542. The Latinized version of his name is [Petrus Nonius]. What are the odds of him inventing… oh wait, they named it after him. That does make more sense.

The nonius is a series of concentric circles traced on the instrument. Working towards the center, each circle has fewer divisions than the previous one. In fact, if the outer ring had 90 marks for 90 degrees, the next ring would have 89, and the following one would have 88.

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