A bunch of unpopulated PCB business cards with rad dead rat artwork.

2024 Business Card Challenge: A Very Annoying Business Card, Indeed

July 8, 2024 by Kristina Panos 7 Comments

Usually the business card itself is the reminder to get in contact with whoever gave it to you. But this is Hackaday, after all. This solar-powered card reminds the recipient to send [Dead Rat Productions] an email by beeping about every two hours, although the gist of that email may simply be begging them to make it stop, provided they didn’t just toss the thing in the garbage.

The full-on, working version of the card is not intended for everyone — mostly serious-looking A-list types that ooze wealth. Most of [Dead Rat Productions]’ pub mates will get an unpopulated version, which could be a fun afternoon for the right kind of recipient, of course.

That person would need a Seeed Studio Xiao SAMD21, a solar panel, plus some other components, like an energy-harvesting chip to keep the battery topped up. Of note, there is a coin cell holder that requires prying with a screwdriver to get the battery out, so there’s really no escaping the beeping without some work on their part. We rather like the artwork on this one, especially the fact that the coin cell sits inside the rat’s stomach. That’s a nice touch.

Swapping Vinyl For Cardboard With This ESP32 Turntable

June 30, 2024 by Bryan Cockfield 15 Comments

Cardboard is a surprisingly durable material, especially in its corrugated form. It’s extremely lightweight for its strength, is easy to work, can be folded and formed into almost any shape, is incredibly inexpensive, and when it has done its duty it can be recycled back into more paper. For these reasons, it’s often used in packaging material but it can be used to build all kinds of things outside of ensuring that products arrive at their locations safely. This working cardboard record player is one example.

While the turntable doesn’t have working records in the sense that the music is etched into them like vinyl, each has its own RFID chip embedded that allows the ESP32 in the turntable’s body to identify them. Each record corresponds to a song stored on an SD card that instructs the ESP32 to play the appropriate song. It also takes care of spinning the record itself with a small stepper motor. There are a few other details on this build that tie it together too, including a movable needle arm held on with a magnet and a volume slider.

As far as a building material goes, cardboard is fairly underrated in our opinion. Besides small projects like this turntable, we’ve also seen it work as the foundation for a computer, and it even has the strength and durability to be built into a wall or even used as shelving material. And, of course, it’s a great material to use when prototyping new designs.

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Showing a Raspberry Pi 4 board connected to an ESP32 devboard using jumper wires for the purposes of this project

ESP-Hosted Turns ESP32 Into Linux WiFi/BT Adapter

June 25, 2024 by Arya Voronova 25 Comments

While we are used to USB WiFi adapters, embedded devices typically use SDIO WiFi cards, and for good reasons – they’re way more low-power, don’t take up a USB port, don’t require a power-sipping USB hub, and the SDIO interface is widely available. However, SDIO cards and modules tend to be obscure and proprietary beyond reason. Enter ESP-Hosted – Espressif’s firmware and driver combination for ESP32 (press release)(GitHub), making your ESP32 into a WiFi module for either your Linux computer (ESP-Hosted-NG) or MCU (ESP-Hosted-FG). In particular, ESP-Hosted-NG his turns your SPI- or SDIO-connected ESP32 (including -S2/S3/C2/C3/C6 into a WiFi card, quite speedy and natively supported by the Linux network stack, as opposed to something like an AT command mode.

We’ve seen this done with ESP8266 before – repurposing an ESP8089 driver from sources found online, making an ESP8266 into a $2 WiFi adapter for something like a Pi. The ESP-Hosted project is Espressif-supported, and it works on the entire ESP32 lineup, through an SDIO or even SPI interface! It supports 802.11b/g/n and even Bluetooth, up to BLE5, either over an extra UART channel or the same SDIO/SPI channel; you can even get BT audio over I2S. If you have an SPI/SDIO port free and an ESP32 module handy, this might just be the perfect WiFi card for your Linux project!

There are some limitations – for instance, you can’t do AP mode in the NG (Linux-compatible) version. Also, part of the firmware has blobs in it, but a lot of the firmware and all of the driver are modifiable in case you need your ESP32 to do even more than Espressif has coded in – this is not fully open-source firmware, but it’s definitely way more than the Broadcom’s proprietary onboard Raspberry Pi WiFi chip. There’s plenty of documentation, and even some fun features like raw transport layer access. Also, of note is that this project supports ESP32-C6, which means you can equip your project with a RISC-V-based WiFi adapter.

Title image from [zhichunlee].

ESP32 Brings New Features To Classic Geiger Circuit

June 24, 2024 by Tom Nardi 4 Comments

There’s no shortage of Geiger counter projects based on the old Soviet SBM-20 tube, it’s a classic circuit that’s easy enough even for a beginner to implement — so long as they don’t get bitten by the 400 volts going into the tube, that is. Toss in a microcontroller, and not only does that circuit get even easier to put together and tweak, but now the features and capabilities of the device are only limited by how much code you want to write.

Luckily for us, [Omar Khorshid] isn’t afraid of wrangling some 0s and 1s, and the result is the OpenRad project. In terms of hardware, it’s the standard SBM-20 circuit augmented with a LILYGO ESP32 development board that includes a TFT display. But where this one really shines is the firmware.

With the addition of a few hardware buttons, [Omar] was able to put together a very capable interface that runs locally on the device itself. In addition, the ESP32 serves up a web page that provides some impressive real-time data visualizations. It will even publish its data via MQTT if you want to plug it into your home automation system or other platform.

Between the project’s Hackaday.io page and GitHub repository, [Omar] has done a fantastic job of documenting the project so that others can recreate it. That includes providing the schematics, KiCad files, and Gerbers necessary to not only get the boards produced and assembled, but modified should you want to adapt the base OpenRad design.

This project reminds us of the uRADMonitor, which [Radu Motisan] first introduced in 2014 to bring radiation measuring to the masses. This sort of hardware has become far more accessible over the last decade, bringing the dream of a globally distributed citizen-operated network of radiation and environmental monitors much closer to reality.

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A Simple Laser Harp MIDI Instrument

June 19, 2024 by Dave Rowntree 5 Comments

Craig Lindley is a technical author and a prolific maker of things. This simple project was his first attempt to create a laser harp MIDI device. While on vacation, Craig saw a laser harp with only three strings and decided to improve upon it by expanding it to twelve strings. The principle of operation is straightforward: twelve cheap diode laser modules aim a beam towards an LDR, which changes resistance if the light level changes when the beam is interrupted.

The controller is a simple piece of perf board, with a Wemos D1 mini ESP32 module flanked by some passives, a barrel socket for power, and the usual DIN connector for connecting the MIDI instrument. Using the ESP32 is a smart choice, removing all the need for configuration and user indication from the physical domain and pushing it onto a rarely-needed webpage. After a false start, attempting to use a triangular frame arrangement, [Craig] settled upon a simple linear arrangement of beams held within a laser-cut wooden box frame. Since these laser modules are quite small, some aluminium rod was machined to make some simple housings to push them into, making them easier to mount in the frame and keeping them nicely aligned with their corresponding LDR.

Sadly, the magnetic attachment method [Craig] used to keep the LDRs in place and aligned with the laser didn’t work as expected, so it was necessary to reach for the hot glue. We’ve all done that!

An interesting addition was using an M5 stack Unit-Synth module for those times when a proper MIDI synthesiser was unavailable. Making this luggable was smart, as people are always fascinated with laser harps. That simple internal synth makes travelling to shows and events a little easier.

Laser harps are nothing new here; we have covered plenty over the years. Like this nice build, which is more a piece of art than an instrument, one which looks just like a real harp and sounds like one, too, due to the use of the Karplus-Strong algorithm to mimic string vibrations.

BikeBeamer Adds POV Display To Bicycle Wheels

June 11, 2024 by Bryan Cockfield 16 Comments

Unless you’re living in a bicycle paradise like the Netherlands, most people will choose to add some sort of illumination to their bicycle to help drivers take note that there’s something other than a car using the road. Generally, simple flashing LEDs for both the front and the rear is a pretty good start, but it doesn’t hurt to add a few more lights to the bicycle or increase their brightness. On the other hand, if you want to add some style to your bicycle lighting system then this persistence of vision (POV) display called the BikeBeamer from [locxter] might be just the thing.

The display uses four LED strips, each housed in their own 3D printed case which are installed at 90-degree angles from one another in between the spokes of a standard bicycle wheel. An ESP32 sits at the base of one of the strips and is responsible for storing the image and directing the four displays. This is a little more complex than a standard POV display as it’s also capable of keeping up with the changing rotational speeds of the bicycle wheels when in use. The design also incorporates batteries so that no wires need to route from the bike frame to the spinning wheels.

This is an ongoing project for [locxter] as well, meaning that there are some planned upgrades even to this model that should be in the pipe for the future. Improving the efficiency of the code will hopefully allow for more complex images and even animations to be displayed in the future, and there are also some plans to improve the PCB as well with all surface-mount components. There are a few other ways to upgrade your bike’s lighting as well, and we could recommend this heads-up headlight display to get started.

ESP32 Powered Crunch-E Makes Beats On The Go

June 11, 2024 by Tom Nardi 8 Comments

There’s no shortage of devices out there for creating electronic music, but if you’re just looking to get started, the prices on things like synthesizers and drum machines could be enough to give you second thoughts on the whole idea. But if you’ve got a well stocked parts bin, there’s a good chance you’ve already got most of what you need to build your own Crunch-E.

Described by creator [Roman Revzin] as a “keychain form factor music-making platform”, the Crunch-E combines an ESP32, an MAX98357 I2S audio amplifier, an array of tactile buttons, and a sprinkling of LEDs and passives. It can be built on a perfboard using off-the-shelf modules, or you can spin up a PCB if you want something a bit more professional. It sounds like there’s eventually going to be an option to purchase a pre-built Crunch-E at some point as well.

But ultimately, the hardware seems to be somewhat freeform — the implementation isn’t so important as long as you’ve got the major components and can get the provided software running on it.

The software, which [Roman] is calling CrunchOS, currently provides four tracks, ten synth instruments, and two drum machine banks. Everything can be accessed from a 4 x 4 button array, and there’s a “cheat sheet” in the documentation that shows what each key does in the default configuration. Judging by the demo video below, it’s already an impressively capable platform. But this is just the beginning. If everything goes according to plan and more folks start jamming on their own Crunch-E hardware, it’s not hard to imagine how the software side can be expanded and adapted over time.

Over the years we’ve seen plenty of homebrew projects for producing electronic music, but the low-cost, simple construction, and instant gratification nature of the Crunch-E strikes us as a particularly compelling combination. We’re eager to see where things develop from here.

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