Pi Pico Calculates Water Usage

February 25, 2023 by Bryan Cockfield 18 Comments

Modern WiFi-enabled microcontrollers have made it affordable and easy to monitor everything from local weather information to electricity usage with typically no more than a few dollars worth of hardware and a little bit of programming knowledge. Monitoring one’s own utility data can be a little bit more difficult without interfering with the metering equipment, but we have seen some clever ways of doing this over the years. The latest is this water meter monitoring device based on a Raspberry Pi Pico.

The clever thing here isn’t so much that it’s based on the tiniest of Raspberry Pis, but how it keeps track of the somewhat obscured water flow information coming from the meter. Using a magnetometer placed close to the meter, the device can sense the magnetic field created as water flows through the meter’s internal sensors. The magnetic field changes in a non-obvious way as water flows through it, so the program has to watch for specific peaks in the magnetic field. Each of these specific waveforms the magnetometer detects counts to 0.0657 liters of water, which is accurate for most purposes.

For interfacing with a utility meter, this is one of the more efficient and elegant hacks we’ve seen in a while. There have, of course, been other attempts to literally read the meter using web cams and computer vision software, but the configuration for these builds is much more complex than something like this. You can interface with plenty of utility meters other than water meters, too, regardless of age.

This Camera Produces A Picture, Using The Scene Before It

February 25, 2023 by Jenny List 23 Comments

It’s the most basic of functions for a camera, that when you point it at a scene, it produces a photograph of what it sees. [Jasper van Loenen] has created a camera that does just that, but not perhaps in the way we might expect. Instead of committing pixels to memory it takes a picture, uses AI to generate a text description of what is in the picture, and then uses another AI to generate an image from that picture. It’s a curiously beautiful artwork as well as an ultimate expression of the current obsession with the technology, and we rather like it.

The camera itself is a black box with a simple twin-lens reflex viewfinder. Inside is a Raspberry Pi that takes the photo and sends it through the various AI services, and a Fuji Instax Mini printer. Of particular interest is the connection to the printer which we think may be of interest to quite a few others, he’s reverse engineered the Bluetooth protocols it uses and created Python code allowing easy printing. The images it produces are like so many such AI-generated pieces of content, pretty to look at but otherworldly, and weird parallels of the scenes they represent.

It’s inevitable that consumer cameras will before long offer AI augmentation features for less-competent photographers, meanwhile we’re pleased to see Jasper getting there first.

Testing The Raspberry Pi Debug Probe

February 23, 2023 by Jenny List 14 Comments

We mentioned the Raspberry Pi Debug Probe when it was launched, a little RP2040-based board that provides both a USB-to-UART and an ARM SWD debug interface. [Jeff Geerling] was lucky enough to snag one, and he’s put it through its paces in a handy blog post.

The first question he poses is: why buy the Pi offering when cheaper boards can be found on AliExpress and the like? It’s easily answered by pointing to the ease of setting up, good documentation and support, as well as the device’s reasonable price compared to other commercial probes. It also answered a personal question here as he hooked it up to a Pico, why it has three jumpers and not the more usual multi-way header we’ve seen on other ARM platforms. We should have looked at a Pico more closely of course, because it matched neatly to the Pi product. On the Pico they’re at the edge, while on the Pico W they’re in the center.

No doubt if the latest addition to the Pi stable has any further revelations we’ll bring them to you. But it’s worth a quick look at this piece to see a real experience with their latest. Meanwhile, take a quick look at our launch coverage.

New Product: The Raspberry Pi Debug Probe

February 21, 2023 by Jenny List 35 Comments

It’s fair to say that among the new product launches we see all the time, anything new from the folks at Raspberry Pi claims our attention. It’s not that their signature Linux single-board computers (SBCs) are necessarily the best or the fastest hardware on paper, but that they’re the ones with meaningful decade-plus support. Add to that their RP2040 microcontroller and its associated Pico boards, and they’re the one to watch.

Today we’ve got news of a new Pi, not a general purpose computer, but useful nevertheless. The Raspberry Pi Debug Probe is a small RP2040-based board that provides a SWD interface for debugging any ARM microcontroller as well as a more generic USB to UART interface.

The article sums up nicely what this board does — it’s for bare metal ARM coders, and it uses ARM’s built-in debugging infrastructure. It’s something that away from Hackaday we’ve seen friends using the 2040 for as one of the few readily available chips in the shortage, and it’s thus extremely convenient to have readily available as a product.

So if you’re a high level programmer it’s not essential, but if you’re really getting down to the nuts-and-bolts of an ARM microcontroller then you’ll want one of these. Of course, it’s by no means the first SWD interface we’ve seen, here’s one using an ESP32.

Automating The Most Analog Of HVAC Equipment

February 20, 2023 by Bryan Cockfield 35 Comments

Burning wood, while not a perfect heating solution, has a number of advantages over more modern heating appliances. It’s a renewable resource, doesn’t add carbon to the atmosphere over geologic time scales like fossil fuels do, can be harvested locally using simple tools, and it doesn’t require any modern infrastructure to support it. That being said, wood stoves aren’t something that are very high-tech and don’t lend themselves particularly well to automation as a result, at least with the exception of this wood stove from [jotulf45v2].

While this doesn’t automate the loading or direct control of a modern pellet stove, it does help [jotulf45v2] know when the best times are for loading more wood into the stove and helps keep the stove in the right temperature range to avoid the dangerous formation of creosote on the inside of his chimney caused by low temperature burns. Two temperature sensors, one on the stovetop and the other on the stove pipe, monitor the stove exhaust temperature. They feed data to a Node-RED system running on a Raspberry Pi which automatically notifies the user by text message when certain stove temperatures are reached.

For anyone heating with wood, tools like this are indispensable to help avoid spending an otherwise unnecessary amount of time getting a fire up to temperature quickly without over-firing the stove. Modern pellet stoves have some more modern conveniences like this built in, but many of the perks of using cord wood are lost with these devices. There are plenty of other ways to heat with wood too; take a look at this custom wood boiler which serves as a hot water heater.

Ploopy Builds Open Source RP2040-Powered Headphones And You Can Too!

February 15, 2023 by Dave Rowntree 16 Comments

We’ve seen many DIY headphones projects on these fair pages over the years, but not many that are quite as DIY as the Ploopy Headphones. What makes this project interesting is the sheer depth of the construction, with every single part being made from what we might call base materials. Materials such as 3D printer filament, foam and felt, and the usual metallic vitamins.

The electronics are fairly straightforward, with an RP2040 functioning as the USB audio interface and equalizer function. Audio samples are emitted as I²S into a PCM3050 24-bit stereo codec which generates a pair of differential output audio signals. These are then converted from differential to single-ended signals and passed on to the coil drivers. The coil drivers consist of no fewer than eight-paralleled opamps per channel. All of this is powered by the USB-C connection to the host computer. Whilst a kit of parts is available for this, you can make your own if you wish, as the full source (Altium designer needed for tweaks) is available on the Ploopy headphone GitHub.

Many DIY headphone builds would likely be using off-the-shelf speaker units, with large parts of the ear cups being taken from spare parts kits for commercial offerings. But not the Ploopy. The drivers are constructed from flex PCB coils with a standard TRRS jack on each side. Magnets for these coils to react against are held in a 3D-printed frame that is attached to the outer cover. The coils are aligned with a special jig and bonded to the ‘driver foam’ with some 3M VHB tape.

The ear cups are constructed with some 3D printed rings, foam pieces, and simple woven material. The resonator plates push into the inner side of the cup, and the assembly simply screws to the driver assembly. The incredibly detailed assembly wiki makes it look easy, but we reckon there are a few tricky steps in there to trip the unwary. The headband again consists of printed spring sections, some woven material, and foam with a few metallic vitamins thrown in. That makes it sounds simple, but it isn’t.

On the whole the build looks fantastic, but what does it sound like? The Ploopy team has tested them against a pair of Sennheiser HDRXX giving a broadly comparable response, but we’re no audio experts, and the proof, as always, is in the wearing. This project seems to be the ultimate in audio tweakability, with the punchy RP2040 capable of running six audio filters at the full 48 KHz, 16-bit audio, though, the PCM3050 is capable of more.

Want to build some headphones, but need a Bluetooth interface? We got you covered. Can 3D printed headphones ever compare to the big names? We’ll see.

How To Roll Your Own Custom Object Detection Neural Network

February 13, 2023 by Donald Papp 2 Comments

Real-time object detection, which uses neural networks and deep learning to rapidly identify and tag objects of interest in a video feed, is a handy feature with great hacker potential. Happily, it’s also possible to make customized CNNs (convolutional neural networks) tailored for one’s own needs, and that process just got easier thanks to some new documentation for the Vizy “AI camera” by Charmed Labs.

Charmed Labs has been making hacker-friendly machine vision devices for a long time, and the Vizy camera impressed us mightily when we checked it out last year. Out of the box, Vizy has a perfectly functional object detector application that runs locally on the device, and can detect and tag many common everyday objects in real time. But what if that default application doesn’t quite meet one’s project needs? Good news, because it’s possible to create a custom-trained CNN, and that process got a lot more accessible thanks to step-by-step examples of training a model to recognize hands doing rock-paper-scissors.

Person and cat with machine-generated tags identifying them — Default object detection works well, but sometimes one needs custom results.

The basic process is this: Start with a variety of images that show the item of interest. Then identify and label the item of interest in each photo. These photos (a “training set”) are then sent to Google Colab, which will be used to generate a neural network. The resulting CNN model can then be downloaded and used, to see how well it performs.

Of course things rarely work perfectly the first time around, so at this point it’s pretty common for some refinement to be needed to increase accuracy. Luckily there are a number of tools to help do this without creating a new model from scratch, so it’s just a matter of tweaking until things perform acceptably.

Google Colab is free and the resulting CNNs are implemented in the TensorFlow Lite framework, meaning it’s possible to use them elsewhere. So if custom object detection has been holding up a project idea of yours, this might be what gets you over that hump.