Hacker Spends A Few Cycles Upgrading An Under-Desk Bike

May 6, 2021 by Kristina Panos 12 Comments

Pandemic got you way behind on your exercise goals? Us too. But not [codaris] who bought an under-desk bike to get in a bit of cycling while banging away on the keyboard. The only bad thing about this bike is the accompanying app — it’s all-around weak and requires too many steps just to get to peddlin’. It pays to know thyself, and [codaris] knows that this will be a major de-motivator and made a desktop app that does it all, including/starting up as soon as the pedals start spinning.

[codaris] built a Windows application that displays workout data in real time and then saves the stats in a SQLite database after the pedaling stops. It took a fair amount of work to get there, logging the Bluetooth traffic during a ride and comparing that with Wireshark output from a live session to decode the communication between the bike and the app. Turns out there are six commands total, and [codaris] really only needs three — Connect, Start Workout, and Continue Workout.

The app displays the elapsed workout time, speed, distance traveled, and the current RPM. We love that it starts logging and displaying data as soon as [codaris] starts pedaling, because that would be a major goal for us, too.

There’s more than one way to hack a bike. [codaris] was inspired by [ptx2]’s excellent work to un-brick a much more expensive bike with a Raspberry Pi.

Thanks for the tip, [Jhart99]!

A Wireless Speaker Pair From Dead Earbuds

May 5, 2021 by Danie Conradie 23 Comments

Building a Bluetooth speaker is easy with the availability of cheap Bluetooth receivers, but surprisingly there isn’t a simple way to build a pair of truly wireless stereo speakers. [Matt] from DIY Perks realized that modern Bluetooth earbuds contain all the electronics to do just that.

Due to the popularity of these earbuds, a broken pair can be picked up very cheaply on eBay. Usually, it’s only the battery or speaker unit that give out, neither of which are required for this build. [Matt] goes through the process of taking a pair of earbuds apart, and then soldering on battery and speaker wires. The speaker wires are connected to an audio amp, which drives a mid-range and treble speaker driver, and a subwoofer. The outputs to the amp are also filtered to match the speakers. Power is provided by a set of four 18650 cells.

[Matt] housed the driver and electronics in some attractive CNC machined wood enclosures. In the video, he places a lot of emphasis on properly sealing all the gaps to get the best possible audio quality. As with all of his projects, the end result looks and performs like a high-end commercial product. We’re almost surprised that he didn’t add any brass to the speakers, as he did on his USB-C monitor or PS5 enclosure build. Continue reading “A Wireless Speaker Pair From Dead Earbuds” →

Soundbar Bested By Virtual Android Bluetooth Sniffer

May 2, 2021 by Tom Nardi 12 Comments

Out of the box, the Yamaha YAS-207 soundbar can be remotely controlled over Bluetooth, but only when using a dedicated application on iOS or Android. Users who want to command their hardware with their computer, or any other Bluetooth device for that matter, are left out in the cold. Or at least they were, before [Wejn] got on the case.

To capture the communication between the soundbar and the application, [Wejn] first installed Android-x86 in a virtual machine on his computer and then enabled the “Bluetooth HCI snoop log” within Developer Settings. From there, a netcat command running on the virtual Android device continually sent the contents of the btsnoop_hci.log file out to Wireshark on his Linux desktop. As he hit buttons in the Yamaha application, he could watch the data come in live. We’ve seen plenty of people use Android’s integrated Bluetooth packet capture in the past, but never quite like this. It’s certainly a tip worth mentally filing away for the future.

The Pi can now control the TOSLINK connected speakers.

From there, things move pretty quickly. [Wejn] is able to determine that the devices are communicating over a virtual serial port, and starts identifying individual command and response packets. It turns out the commands closely mirror the NEC IR codes that he’d previously decoded on a whim, which helped clear things up. Once the checksum was sorted out, writing some code that can talk to the soundbar from his Raspberry Pi media player was the next logical step.

[Wejn] combined this with the Shairport Sync project, which lets the Raspberry Pi turn on the speaker and switch the input over when he wants to stream AirPlay from his phone. But of course, the same technique could be applied to whatever source of digital audio captures your fancy.

This is one of those posts you should really read in its entirety to truly appreciate. While every device is going to be different, the basic principles and workflow that [Wejn] demonstrates in this project will absolutely be useful in your own reverse engineering adventures. If you’re more of a visual learner, we recently covered a series of YouTube tutorials that cover sniffing BLE devices that’s not to be missed as well.

Turn On Your Lights With A Wave Of A Magic Wand

April 22, 2021 by Lewin Day 14 Comments

Smartphones and voice assistants are the typical way most of us interact with our smart devices around the home, but it doesn’t have to be the only way. [Sam March] wanted things to feel a little more magical – so built a wand to do the job instead.

The wand relies on a DA14531 Bluetooth Low Energy (BLE) system-on-chip, and is paired with what appear to be smart plugs running on the same hardware. With an accelerometer in the wand, it’s able to detect waving motions, and then signal the smartplugs over Bluetooth to switch outlets on or off. As far as the magic side of things is concerned, [Sam] took his lead from [Arthur C. Clarke], who famously stated “Any sufficiently advanced technology is indistinguishable from magic.” Thus, efforts were made to miniaturize the electronics down to a single tiny PCB, allowing it to be secreted inside a turned wooden wand that’s wrapped in leather.

The end result is a fun project that’s also probably useful when [Sam] wants to turn the lights off without getting out of bed. We could imagine that, configured properly to work on a room-by-room basis, it could be useful for guests who don’t know where the light switches are.

If the name sounds familiar, it’s because we’ve heard from [Sam] before – with his great DIY smartwatch build. Video after the break.

Continue reading “Turn On Your Lights With A Wave Of A Magic Wand” →

Ferrofluid Dances In Custom Bluetooth Speaker

April 21, 2021 by Bryan Cockfield 12 Comments

Ferrofluids, as the name implies, are liquids that respond to magnetic fields. They were originally developed for use by NASA as rocket fuel but are available to the general public now for anyone who wants to enjoy their unique properties. For [Dakd Jung], that meant building a special chamber into a Bluetooth speaker that causes the ferrofluid inside to dance along with the rhythm of the music.

This project isn’t quite as simple as pushing the ferrofluid container against a speaker, though. A special electromagnetic device similar to a speaker was used specifically to manipulate the fluid, using a MSGEQ7 equalizer to provide the device with only a specific range of frequencies best tailored for the fluid’s movement. The project includes two speakers for playing the actual music that point upward, and everything is housed inside of a 3D-printed case. There were some additional hurdles to overcome as well, like learning that the glass needed a special treatment to keep the ferrofluid from sticking to it.

All in all it’s a unique project that not only brings sound to a room but a pleasing physical visualization as well. Being able to listen to music or podcasts on a portable speaker, rather than the tinny internal speakers of a phone or laptop, is the sort of thing you think you can live without until you get used to having higher quality sound easily and in every place you go. And, if there’s a way to improve on that small but crucial foundation with something like a dancing ferrofluid that moves with the music the speaker is playing, then we’re going to embrace that as well.

DIY Wireless Serial Adapter Speaks (True) RS-232

April 18, 2021 by Donald Papp 80 Comments

There is a gotcha lurking in wait for hackers who look at a piece of equipment, see a port labeled “Serial / RS-232”, and start to get ideas. The issue is the fact that the older the equipment, the more likely it is to be a bit old-fashioned about how it expects to speak RS-232. Vintage electronics may expect the serial data to be at bipolar voltage levels that are higher than what the typical microcontroller is used to slinging, and that was the situation [g3gg0] faced with some vintage benchtop equipment. Rather than deal with cables and wired adapters, [g3gg0] decided to design a wireless adapter with WiFi and Bluetooth on one end, and true RS-232 on the other.

The adapter features an ESP32 and is attached to a DB-9 plug, so it’s nice and small. It uses the ST3232 chip to communicate at 3 V logic levels on the microcontroller side, supports bipolar logic up to +/-13 V on the vintage hardware side, and a rudimentary web interface allows setting hardware parameters like baud rate. The nice thing about the ST3232 transceiver is that it is not only small, but can work from a 3 V supply with only four 0.1 uF capacitors needed for the internal charge pumps.

As for actually using the adapter, [g3gg0] says that the adapter’s serial port is exposed over TCP on port 23 (Telnet) which is supported by some programs and hardware. Alternately, one can connect an ESP32 to one’s computer over USB, and run firmware that bridges any serial data directly to the adapter on the other end.

Design files including schematic, bill of materials, and PCB design are shared online, and you can see a brief tour of the adapter in the video, embedded below.

Continue reading “DIY Wireless Serial Adapter Speaks (True) RS-232” →

Heads Up: Smart Glass Multimeter

April 18, 2021 by Al Williams 20 Comments

Sometimes it is hard to probe a circuit and then look over at the meter. [Electronoobs] decided to fix that problem by making a Google Glass-like multimeter using an OLED screen and Bluetooth module.

The custom PCB doesn’t have many surprises. A small board has a controller, a battery charger, a display, and a Bluetooth module. One thing he did forget is a switch, though, so the board is always on unless you arrange an external switch.

Continue reading “Heads Up: Smart Glass Multimeter” →