bluetooth

578 Articles

Hard Hat Becomes Bluetooth Direction Finder

September 30, 2025 by 10 Comments

Have you ever wanted to find a Bluetooth device out in the wild while looking like the comic relief character from a science-fiction series? You might like Dendrite, the direction-finding hat from [SolidStat3].

Dendrite is intended for hunting down Bluetooth devices. It’s capable of direction estimation based on signal strength readings from four ESP32 microcontrollers mounted on an off-the-shelf hard hat. Each ESP32 searches for BLE devices in the immediate area and reports the apparent signal strength to a fifth ESP32, which collates readings from all units. It then runs a simple multilateration algorithm to estimate the direction of the device. This information is then displayed via a ring of addressable LEDs around the perimeter of the hat. White LEDs marking the direction of the detected device. The only problem? You can’t see the LEDs while you’re wearing the hat. You might need a friend to help you… or you can simply take it off to see what it’s doing.

Ultimately, this project is a useful direction-finding hard hat that would also make a perfect prop from an episode of Inspector Spacetime. We’ve covered direction finding in other contexts before, too. Meanwhile, if you’re cooking up your own innovative hard hat (or radio) hacks, don’t hesitate to let us know!

Bluetooth Earrings Pump Out The Tunes

September 27, 2025 by 14 Comments

When you think of a Bluetooth speaker, you’re probably picturing a roughly lunchbox-sized device that pumps out some decent volume for annoying fellow beachgoers, hikers, or public transport users. [Matt Frequencies] has developed something in an altogether different form factor—tiny Bluetooth speakers you can dangle from your earlobes! They’re called Earrays, and they’re awesome.

The build started with [Matt] harvesting circuit boards from a pair of off-the-shelf Bluetooth earbuds. These are tiny, and perfect for picking up a digital audio stream from a smartphone or other device, but they don’t have the grunt to drive powerful speakers. Thus, [Matt] hooked them up to a small Adafruit PAM8302A amplifier board, enabling them to drive some larger speaker drivers that you can actually hear from a distance. These were then installed in little 3D printed housings that are like a tiny version of the speaker arrays you might see hanging from the rigging at a major dance festival. Throw on a little earring hook, and you’ve got a pair of wearable Bluetooth speakers that are both functional, fashionable, and very audible!

[Matt] has continued to develop the project, even designing a matching pendant and a charging base to make them practical to use beyond a proof-of concept. Despite the weight of the included electronics, they’re perfectly wearable, as demonstrated by [DJ Kaizo Trap] modelling the hardware in the images seen here.

We’ve seen plenty of great LED earrings over the years, but very few jewelry projects in the audio space thus far. Perhaps that will change in future—if you pursue such goals, let us know!

Bringing Bluetooth To The Zune

September 27, 2025 by 10 Comments

The Zune might have joined the portable media player game too late to ever really be competition for the iPod, but that doesn’t mean it didn’t pick up some devoted fans along the way. Some of them are still breathing new life into the device, such as [The Director of Legal Evil Emeritus] at the Louisville Hackerspace, with this project that gives it Bluetooth capability.

As far as media players go, there’s still some solid reasons to rock a Zune. Compared to other devices of the era, it offers a better DAC, an FM tuner, and no iTunes reliance. The goal of this project was to bring a bit of modern functionality without having to do any modification of the Zune itself. As the player supported docks with IR remotes, this build involves using an ESP32 to listen to the Bluetooth signal coming from the speakers, interpret any button presses, and forward them along to the Zune’s dock.

There is a dedicated scene for these old music players, but this build is unique for not needing to crack open the case and splice in a Bluetooth module. Even then, those typically don’t have the ability to interact with things like this speaker with its integrated control buttons.

We don’t often seen Zune hacks come our way — the last time Microsoft’s player graced these pages was in 2010, when the Open Zune Development Kit was released.

Thanks to [JAC_101] for the tip!

The Android Linux Commander

September 9, 2025 by 7 Comments

Last time, I described how to write a simple Android app and get it talking to your code on Linux. So, of course, we need an example. Since I’ve been on something of a macropad kick lately, I decided to write a toolkit for building your own macropad using App Inventor and any sort of Linux tools you like.

I mentioned there is a server. I wrote some very basic code to exchange data with the Android device on the Linux side. The protocol is simple:

  • All messages to the ordinary Linux start with >
  • All messages to the Android device start with <
  • All messages end with a carriage return

Security

You can build the server so that it can execute arbitrary commands. Since some people will doubtlessly be upset about that, the server can also have a restrictive set of numbered commands. You can also allow those commands to take arguments or disallow them, but you have to rebuild the server with your options set.

There is a handshake at the start of communications where Android sends “>.” and the server responds “<.” to allow synchronization and any resetting to occur. Sending “>#x” runs a numbered command (where x is an integer) which could have arguments like “>#20~/todo.txt” for example, or, with no arguments, “>#20” if you just want to run the command.

If the server allows it, you can also just send an entire command line using “>>” as in: “>>vi ~/todo.txt” to start a vi session.

Continue reading “The Android Linux Commander” →

A photo of the PCB from the charging case

Anker Soundcore Space A40 Earbuds Teardown

September 7, 2025 by 3 Comments

Wireless earbuds are notoriously tiny. Want to see inside? [MCH170] did and published a Soundcore Space A40 Teardown.

In this teardown, you’ll see inside the charging case and one of the earbuds. Starting with the case, removing the back cover revealed the charging coil and a few screws holding the PCB in place. Removing the screws allows for removing the coil. The main PCB and the magnets that hold the earbuds in place are then visible. The microcontroller is an SS881Q from Sinhmicro. The back side of the main circuit board has a handful of SMD components, including some status LEDs. The battery is a 13450 with a nominal voltage of 3.72V and a capacity of 800mAh or 2.967Wh.

Continue reading “Anker Soundcore Space A40 Earbuds Teardown” →

The Android Bluetooth Connection

August 27, 2025 by 14 Comments

Suppose someone came to talk to you and said, “I need your help. I have a Raspberry Pi-based robot and I want to develop a custom Android app to control it.” If you are like me, you’ll think about having to get the Android developer tools updated, and you’ll wonder if you remember exactly how to sign a manifest. Not an appealing thought. Sure, you can buy things off the shelf that make it easier, but then it isn’t custom, and you have to accept how it works. But it turns out that for simple things, you can use an old Google Labs project that is, surprisingly, still active and works well: MIT’s App Inventor — which, unfortunately, should have the acronym AI, but I’ll just call it Inventor to avoid confusion.

What’s Inventor? It lives in your browser. You lay out a fake phone screen using drag and drop, much like you’d use QT Designer or Visual Basic. You can switch views and attach actions using a block language sort of like Scratch. You can debug in an emulator or on your live phone wirelessly. Then, when you are ready, you can drop an APK file ready for people to download. Do you prefer an iPhone? There’s some support for it, although that’s not as mature. In particular, it appears that you can’t easily share an iPhone app with others.

Is it perfect? No, there are some quirks. But it works well and, with a little patience, can make amazingly good apps. Are they as efficient as some handcrafted masterpiece? Probably not. Does it matter? Probably not. I think it gets a bad rep because of the colorful blocks. Surely it’s made for kids. Well, honestly, it is. But it does a fine job, and just like TinkerCad or Lego, it is simple enough for kids, but you can use it to do some pretty amazing things.

Continue reading “The Android Bluetooth Connection” →

Bad To The Bluetooth: You Shouldn’t Use This Jammer

August 21, 2025 by 12 Comments

Back in the day, an FM bug was a handy way to make someone’s annoying radio go away, particularly if it could be induced to feedback. But these days you’re far more likely to hear somebody’s Bluetooth device blasting than you are an unruly FM radio.

To combat this aural menace, [Tixlegeek] is here with a jammer for the 2.4 GHz spectrum to make annoying Bluetooth devices go silent. While it’s not entirely effective, it’s still of interest for its unashamed jankiness. Besides, you really shouldn’t be using one of these anyway, so it doesn’t really matter how well it works.

Raiding the AliExpress 2.4 GHz parts bin, there’s a set of NRF24L01+ modules that jump around all over the band, a couple of extremely sketchy-looking power amplifiers, and a pair of Yagi antennas. It’s not even remotely legal, and we particularly like the sentence “After running the numbers, I realized it would be cheaper and far more effective to just throw a rock at [the Bluetooth speaker]“. If there’s a lesson here, perhaps it is that effective jamming comes in disrupting the information flow rather than drowning it out.

This project may be illegal, but unlike some others we think it (probably) won’t kill you.