Elektor Lab Notes 11: latest projects, ESP32, Matter, 3D printing and more!

Check out the latest installment of Elektor Lab Notes. We cover some of the latest projects we are working on, interesting components and boards, ESP32, Matter, 3D printing and more!

Welcome back to Elektor Lab Notes! Every few weeks, our creative engineers and busy editors post a few lab notes and updates about new DIY electronics projects, industry news, and helpful engineering insights. Feel free to share your thoughts in the Discussion section at the bottom of this page. Share your own lab notes and let us know what you are working on in your lab!

Saad Imtiaz (Senior Engineer, Elektor)

ESP32 Energy Meter project: The ESP32 Energy Meter project is making strides. I've nailed down the schematic and PCB design, and switched things up by placing the order with PCB Way – a change driven by a mix of component shortages and delivery time considerations. The anticipation is palpable as I eagerly await the fully assembled PCB, set to arrive in the first week of the new year. And then, the real fun begins – diving into firmware development!

CaptureCount project: Switching gears, I've been dabbling with the CaptureCount project, powered by the nifty Raspberry Pi 5. It's been a while since I dived into image processing and computer vision, and I'm pleasantly surprised at how much the field has evolved. There's a wealth of resources out there, making it a breeze to get back into the groove. Stay tuned for more on this project in the upcoming editions of Elektor Magazine.

Sparkfun MGM240P: Now, let's talk about my first encounter with the Sparkfun MGM240P. As my inaugural Sparkfun board and foray into Matter technology, it's been a learning curve – like discovering the need for a Matter-enabled hub (who knew, right?). But, it's a fantastic board brimming with potential for crafting all sorts of home automation devices. I'm gearing up to share a detailed review soon, so watch this space.

Matter Hub required — Looks like I'll need some more hardware

3D Printing: Last but definitely not least, I tackled setting up Octoprint for my Ender 3 V2 Neo 3D Printer. It's been my trusty companion for small, functional 3D printing tasks. But let's be honest, the back-and-forth trips between rooms to transfer files were getting old. So, I decided to bring some tech magic into the mix! With Octoprint now on a Raspberry Pi, I can control, monitor, and send new prints to my 3D printer right from my computer. It's a game-changer, especially for someone who values convenience as much as I do. If you're like me and prefer to keep things efficient and hassle-free, this is the way to go.

Jean-François Simon (Engineer, Elektor)

SSD Adventures

I have this SSD which, all of a sudden, was no longer recognized by the BIOS. I've checked all the passive components on the board, and they're fine. I've checked the power rails, they're all good too. I thought "maybe a cold solder joint in the Flash chips... Let's put them in the oven with plenty of flux and do a quick reflow". Alas, I was so absorbed in my task that I didn't pay attention and didn't remove the label between the two ICs. As the label is plastic-based rather than paper-based, it shrank under the effect of the heat and displaced the BGAs while the solder was molten.

SSD — Beware of plastic labels! (see glue residue)

So I've got Flash chips well soldered now, but not on their footprints! I've tried to reheat them and move them again with a little tweak of the tweezers, but the 1V8 rail is now short-circuited to ground; a nice 0.0 Ω… Well, there are definitely some balls that have bridged under there!

Well, now all is left to do is reball the Flash chips. There are several methods and plenty of videos on YouTube. I think I will purchase a reballing jig on AliExpress, some stencils, solder balls and practice, practice and practice again until it works. And you, have you ever tried reballing BGA? How did it go?

How To Find Project Ideas?

That’s an interesting question. Sometimes you know you need to start a new project, but you don't really know where to begin. You've got projects on your inspiration list, but you're not sure you want to start with any of them. This is discussed here on the EEVblog.

Now there's a pretty amazing tool you can use to ask questions like “what can I do with XYZ component?” : ChatGPT of course. It can rummage through the internet to find ideas or associations of ideas!

Also, recently I was looking for inspiration for FPGA-based projects, and I came across the ECE5760 course page at Cornell, with some very interesting links: the main course page, also the page listing student projects and finally a list of ideas. The course was taught in the past by Bruce Land, a great professor I heard about many years ago. His other course on AVR microcontrollers on YouTube was fantastic!

These Chips Are Cool

No, I'm not talking about Peltier modules, although it's true that they're very cool, especially on one side. I like discovering new circuits and components, some of which aren't very new at all. Here's a short list. What curious components have you come across lately? Share them in the comments!

Obscure microcontrollers. The GA144 from Green Arrays comes to mind. 144 cores arranged in a matrix, only programmable in Forth, with a development software that uses color as a way of indicating how words should be interpreted, plus a non-standard keyboard layout. That’s not for the faint of heart, and extensive Google search reveals that, errr, it looks like this chip is a solution looking for a problem. It looks like it’s having a hard time convincing people, and few have actually made things with it. Compared with the GA144, even the strange Parallax Propeller looks mainstream. (And there are many projects based on either the Propeller 1 or the Propeller 2, such as this groovy synthesizer)
Potato Semiconductor, making, well, Potato chips. This is serious, they made their own versions of 7400 series logic, except that these can run at 1 GHz. Here is a video from Afrotechmods showing a ring oscillator made with Potato’s own version of a 7404 hex inverter. Sadly, they seem to be out of business, but the Internet Archive has backed up their website. Anyone knows what happened?

Potato Semiconductor — A crispy hex inverter. Source: YouTube/Afrotechmods

The AS3935 Lightning Detector. It is capable of detecting lightning up to 40 km away with an accuracy of 1 km, using an antenna. That is seriously cool.

AS3935 Lightning Detector. Source: Sparkfun

Share your own findings in the comments!

Interesting People to Follow
Robert Feranec. He started out on Youtube a few years ago with PCB routing tutorials using Altium, and now his channel is very successful and covers a whole range of subjects in electronics. I highly recommend it!
Carl Bujega, an engineer from Malta. He has made PCB motor designs and robotics projects, including the development of a four-legged robot that transforms into a small ball. Recently, he has also been experimenting with flexible PCBs in creating unique flapping actuators and has a very interesting electronic engineering YouTube channel.
Wolfgang Griebel, from the blog Electronic Projects For Fun, is passionate about RF, Ham radio, test equipment, power supplies and regulators, high voltage projects, microcontrollers, and more. His blog is packed with highly detailed and informative content, which I found incredibly educational and captivating. Additionally, the construction quality of his projects is consistently excellent.
Jay Carlson is an embedded systems engineer specializing in PCB design, RF, motion control, embedded Linux, low-power wireless, and microcontrollers with many years of experience. I came across his blog twice in one week on two different topics, so I thought I'd mention it! Special mention for this page where he explores no less than 21 different microcontrollers!

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Jens Nickel (Editor-in-Chief, Elektor Magazine)

Wi-Fi Remote Control for Audio Amplifiers: In the previous installment of Lab Notes I already reported briefly about my latest pet project, a Wi-Fi based remote control for small, but high power audio amplifiers. Well, good news: I had a lot of nice development sessions with one of my friends who is an engineer and also a music enthusiast.

Volume Control: It turned out that using a digital potentiometer wasn't a good idea, as the audio signal of the amplifier we are using is going through the main potentiometer directly, and we had noise problems with those digital pots. Instead, we ordered good old Alps motorized pots, and we have driven these with small DC motor driver PCBs. Two controller pins are enough to change the volume of the amp now.

ALPS motorized potentiometer. Source: Conrad

Energy Monitoring: As our amplifiers are powered from Li-ion batteries coming from electric bicycles, we had the idea to also measure the current and voltage, from which we could derive power and energy consumed. I experimented with an INA169 current sensor breakout board at a sampling rate of about 1.000 samples per second. Measuring at this kind of speed is interesting, as the current drawn by the amplifier is changing rapidly due to the music. In fact, on the current waveform you can see kick drum beats as well as the usual breaks and drops that are present in almost all kinds of electronic music. To make energy and battery capacity calculations, some averaging and simple math is needed, so I had the idea to use an extra controller for that, thus freeing up the main controller (e.g. an ESP32, which handles the remote control and communication) from that kind of work.

INA169 current sensor breakout. Source: Adafruit

A New Project: The result is a second project — a kind of intelligent sensor for power, energy and charge, communicating via UART and simple commands with another controller or PC. Of course we will keep you posted, and I’m pretty sure you will also read something about that on our Labs platform and maybe even in the magazine soon.

March/April Edition: We are currently editing our March/April Edition, and traditionally this is when we feature the most Embedded and AI projects and articles, as the latter is one of the most fascinating topics of processor-based electronics. Well, I have to say that I would have liked to feature even more AI stories in last year's March/April edition! This is probably partly due to the fact that the whole Elektor community (Elektor team, as well as external authors and developers) had to get familiar first with all the developing frameworks and platforms, and there are many. Rest assured, in this Edition we will "strike back": we will cover ChatGPT as a help for coding, counting objects with a camera and Edge Impulse, and object recognition, both with the Raspberry Pi and the Jetson Nano, just to name a few of the articles. More about this soon!

C. J. Abate (Director, Content and Lab, Elektor)

I want to thank all of our community members for all the great projects, tips, and insights over the course of 2023! Happy new year. Here are a few of the things I've been working on recently.

Espressif Guest-Edited Edition and Bonus Edition: In early December, we published the Espressif Guest-Edited Edition of Elektor Mag. Since then, we've been releasing portions of a free Bonus Edition. Each week, I post a news item announcing the next installment. Check it out!

Hot Topics — Verticals: Over the past few weeks, I've been working with our editors and management to prepare our content strategy for the next several months. In 2024, our Content Team will focus its content creation efforts on educating and inspiring community members about specific electronics-related subject areas, which we refer to internally as "verticals." The main subject areas are: Power & Energy; Embedded & AI; Test & Measurement; IoT & Sensors; Circuits & Circuit Design; Wireless & Communications; Prototyping & Production; Arduino; Espressif; and Raspberry Pi. As we provide content for each subject area, we invite and encourage your active participation and collaboration. Feel free to submit your article proposals, showcase your projects on the Labs platform, and share your product ideas (such as books or kits) with us. We eagerly anticipate the opportunity to collaborate with you!