iPhone pictured with a lock

Make Your Own BLE-Enabled IOS App From Scratch

Even those readers who are most skeptical of Apple products will like this Bluetooth Low Energy (BLE)-enabled iOS app tutorial from [Akio].

With everything being “connected” these days smartphone applications are of course a ubiquitous part of our existence. We’ve seen plenty of examples connecting your Bluetooth-enabled projects to an Android device, but comparatively fewer tutorials for connecting to iOS devices. This mostly has to do with Android’s much larger market share and also Android’s more open-source friendly business model. Nevertheless, if you do much IoT development either as a hobby or professionally, then you probably find yourself interacting with Apple devices more than you like to admit.

[Akio’s] app is essentially updating a chart, in real-time, with data read from an Adafruit nRF52832 Feather board. He then walks you through all the basics of creating a user interface (UI) using Apple’s Storyboard interface, a simple drag-and-drop scheme similar to something you’ve probably used in many other contexts. [Akio] shows readers how to add buttons for allowing users to interact with the app, labels for displaying data to the user, as well as walks you through Apple’s odd methodology of connecting UI elements to code using IBAction and IBOutlets. The highlight of his tutorial is showing readers how to add charts to their iOS apps which seems to take a few more steps than you might imagine.

[Akio] does a really good job detailing all the relevant functions so that readers will hopefully understand what each piece of the code is doing. And we really enjoyed him adding individual video tutorials for some of the trickier programming steps. He also readily admits that some folks may opt to develop their UI exclusively in code as opposed to the Storyboard but he argues that the Storyboard is still important for beginners and is really handy when the UI is fairly simple.

Of course, in true open-source fashion, [Akio] provides all his code on his GitHub repository so you can clone the repo and run the code yourself as well as credit some of the resources he used while making his app. Two things we really love to see. Hopefully, [Akio’s] tutorial will make connecting to iOS devices seem much less onerous than it once was.

Watch Blender Plugin Make Animated PCB Traces (and More)

[Staacks]’s Blender plugin to animate growth is behind the sweet animation seen above. It’s an add-on that cleverly makes creating slick growth animations easier when using Blender. It isn’t limited to PCB images either, although they do happen to make an excellent example of the process.

The add-on isn’t limited to animating PCB traces.

The idea is that one begins with an image texture with a structure showing a bunch of paths (like a maze, or traces on a PCB), and that gets used as an input. The plugin then uses a path finding algorithm to determine how these paths could grow from an origin point, and stores the relevant data in the color channels of an output image. That output is further used within Blender as the parameters with which to generate the actual animation, resulting in the neat self-creating PCB seen above. That PCB isn’t just for show, by the way. It’s the PCB for [Staacks]’s smart doorbell project.

Blender is an amazingly comprehensive tool for modeling and animation, and while we’ve covered using it to create high-quality KiCad renders, this kind of animation is really something else.

Here is the GitHub repository for the Blender growth tool if you’re interested in giving it a spin. If you’d like to see more first, watch the video embedded below for a showcase of what it’s capable of, and how it works.

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ESP32 board with battery and nearby antenna

How To Easily Set Up Secure OTA Firmware Updates On ESP32

After an electronic IoT device has been deployed into the world, it may be necessary to reprogram or update it. But if physical access to the device (or devices) is troublesome or no longer possible, that’s a problem.

OTA updates allow a device to download new firmware, install it, and reboot itself into the new version. Convenient? Yes. Secure? It definitely needs to be.

Fortunately, over-the-air (OTA) firmware updates are a thing, allowing embedded devices to be reprogrammed over their wireless data connection instead of with a physical hardware device. Security is of course a concern, and thankfully [Refik] explains how to set up a basic framework so that ESP32 OTA updates can happen securely, allowing one to deploy devices and still push OTA updates in confidence.

[Refik] begins by setting up a web server using Ubuntu Linux, and sets up HTTPS using a free SSL certificate from Let’s Encrypt, but a self-signed SSL certificate is also an option. Once that is done, the necessary fundamentals are in place to support deploying OTA updates in a secure manner. A bit more configuration, and the rest is up to the IoT devices themselves. [Refik] explains how to set things up using the esp32FOTA library, but we’ve also seen other ways to make OTA simple to use.

You can watch a simple secure OTA firmware update happen in the video, embedded below. There are a lot of different pieces working together, so [Refik] also provides a second video for those viewers who prefer a walkthrough to help make everything clear. Watch them both, after the break.

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Wooden sticks sound good if you clamp them down at one end.

Popsicle-Stick Piano Sounds Sweet

Technically, this is a kalimbaphone, and not a piano or even a chordophone since there are no strings. But this handcrafted instrument doesn’t just sound sweet, it’s also mellow, and it’s much nicer than you’re probably imagining. Go check out the short build video, which starts with a demo.

[Mash] started by drilling a bunch of holes into a rectangular piece of wood, and then twisted in wood screws far enough to stay in. Then [Mash] laid Popsicle sticks between each set of screws and tuned them one at a time, starting with middle C. The Popsicle stick version didn’t sound so great, so [Mash] upgraded to tongue depressors and moved the black keys up to their own layer. Unfortunately, the owner has turned off embeds for the video, so you’ll have to watch it on YouTube.

We’d love to see [Mash] figure out a way to make the sticks resonate. In the meantime, check out this 3D-printed grand piano mechanism. And if this build has you in the mood to listen to Popcorn on a homemade instrument, well, we’ve got you covered there.

Thanks to [Keith] for the tip!

Brass screen is soldered together into a large mold for cardboard pulp.

How To Make A Classy, Brassy Cardboard Pulp Mold

When we last checked in with prolific prototypist [Eric Strebel], he was perfecting the design of an eco-friendly wireless charger and turning his initial paper prototype into a chipboard version 2.0 that takes manufacturing concerns into consideration. At the end of this second video in a series, [Eric] was printing out the early versions of the form by which he would eventually make a brass screen mold for working with cardboard pulp. You know, the stuff that some egg cartons are made from.

Soldering brass screen into a mold.In the video below, it’s time to build the pulp mold by creating three smaller molds and then joining them into one horizontal mold. The result is a single piece that then gets folded up into a charging stand, much like the egg carton. [Eric] is using brass screen here, but says that copper would be a good choice, too.

After cutting the brass with scissors and pounding them flat, he uses the 3D-printed molds from the previous video to press them into the correct shapes. Each of the three pieces needs a frame, which [Eric] makes from more brass screen, then stitches it to the mold piece with loose screen threads before securing the unions with solder.

Since the weight of all the water would likely bend the brass out of shape, [Eric] finished off the mold by soldering on a frame of flat brass strip. Check out this awesome process below, and stay tuned for the next video when [Eric] pulps some cardboard and pumps out some eco-friendly chargers.

Does this look too complicated? You could always skip the whole mesh mold thing and shape your cardboard confetti directly into 3D printed parts.

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Chipboard prototype of a wireless phone charger with style.

Prototyping Your Way To Better Prototypes

If you’ve ever made a prototype of something before making the “real” one or even the final prototype, you probably already know that hands-on design time can’t be beat. There’s really no substitute for the insight you will glean from having a three-dimensional thing to hold and turn over in your hands for a full assessment. Sometimes you need to prototype an object more than once before investing time, money, and materials into making the final prototype for presentation.

This is [Eric Strebel]’s second video in series about making an eco-friendly wireless phone charger. He made a paper prototype in the first video, and in this follow-up, he refines the idea further and makes a chipboard version of the charger before the final molded paper pulp prototype. The main advantage of the chipboard version is to design the parts so that each one will be easier to pull from its mold in a single piece without any undercuts.

By building the chipboard version first, [Eric] is able to better understand the manufacturing and assembly needs of this particular widget. This way, he can work out the kinks before spending a bunch of time in CAD to create a 3D-printed mold and making the paper pulp prototype itself. He emphasizes that this process is quite different from the 2.5D method of laser-cutting a single piece of chipboard and folding it up into a 3D object like it was a cereal box, which is likely to hide design issues. Be sure to check out the video after the break.

We think this prototype is quite nice-looking, and believe that everything deserves good design. Why should a wireless charger be any different? [Eric] has prototyped in a lot of media, but he seems especially skilled in the art of foam core board. Start with the masterclass and you’ll have a better appreciation for his foam armored vehicle and one of the many ways he smooths out foam parts.

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Build Your Own HV Capacitors

Finding high voltage capacitors can be tricky. Sure, you can buy these capacitors, but they are often expensive and hard to find exactly what you want. [RachelAnne] needed some low-value variable capacitors that would work at 100 kV. So she made some.

Instead of fabricating the plates directly, these capacitors use laminations from a scrap power transformer. These usually have two types of plates, one of which looks like a letter “E” and the other just like a straight bar. For dielectric, the capacitors use common transparency film.

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