Flux Gate Magnetometers Make A Special Current Probe

September 21, 2019 by Jenny List 11 Comments

There are moments when current measurement is required on conductors that can’t be broken to insert a series resistor, nor encircled with a current transformer. These measurements require a completely non-invasive technique, and to satisfy that demand there are commercial magnetometer current probes. These probes are however not for the light of wallet, so [ensgoldmine] has created a much cheaper alternative.

The Texas Instruments GRV425 flux gate magnetometer integrated circuit on its TI evaluation module provides the measuring element placed at the tip of a probe as close as possible to the conductor to be measured, with another GRV425 module at the head of the probe to measure ambient magnetic field for calibration purposes. An Arduino Due measures and processes the readings, chosen due to its higher-resolution ADC than the more ubiquitous Arduino Uno.

The write-up is interesting even if you have no need for a current probe, because of its introduction to these sensing elements. Because it’s a rare first for Hackaday, we’ve never taken a close look at them before other than as an aside when talking about a scientific instrument on Mars.

Atomic Pi Gets A 3D-Printed Mac Makeover

September 15, 2019 by Tom Nardi 6 Comments

The Atomic Pi is a pretty impressive piece of kit for the price, but it’s not exactly a turn-key kind of product. Even to a greater extent than what you might normally expect with a “dev” board like this, the user is responsible for putting together the rest of the pieces required to actually utilize it. But with this design by [Renri Nakano], you can turn the Atomic Pi into something that’s dangerously close to being a practical computer, and a trendy one at that.

Inspired by the 2019 Apple Mac Pro “Cheese Grater”, this 3D printable enclosure for the Atomic Pi is equal parts form and function. It integrates the necessary power supply to get things up and running without the need for the official breakout board or power module, which is good, since at the time of this writing they don’t seem to be available anyway. Plus it has a cool looking power button, so that’s got to count for something.

There’s also an integrated USB hub to give the Atomic Pi a bit more expandability, and a short HDMI extension cable that puts a video port on the back of the case. [Renri] even thought to leave an opening so you could run the wires for your wireless antennas.

At this point, we’ve seen several projects that mimic the unique case design of the 2019 Mac Pro. The level commitment ranges from recreating the design in CAD and milling it out of aluminum to just sticking a Raspberry Pi inside of a literal cheese grater from the kitchen. Naturally we enjoy a well executed Internet meme as much as the next hacker, but all the same, we were glad to see [Renri] put in the effort to make sure this case was more than just a pretty face.

[Thanks to baldpower for the tip.]

Everything You Wanted To Know About Padauk MCUs And More

September 9, 2019 by Maya Posch 40 Comments

At this point you’d need to have lived underneath a rock somewhere on the dark side of the Moon to not have heard about these amazing, 3-cent microcontrollers. A number of places have pitched in on them, but comprehensive reviews, let alone a full-blown review of the entire ecosystem surrounding these Padauk MCUs have been scarce. Fortunately, [Jay Carlson] has put in a lot of effort to collect everything you could possibly want to know about anything Padauk.

The most important take-away is that these MCUs do not have any kind of communication peripherals. UARTs, I2C, and SPI all have to be done in software. They’re not very great at low-power or battery-powered applications due to high power usage. Essentially you’ll be using GPIO pins a lot. On the other hand, its multi-CPU context, FPPA feature is rather interesting, with the article covering it in detail.

As for the development tools, [Jay] came away very impressed with the In-Circuit Emulation (ICE) instead of running code on an MCU, as this can reduce development times significantly. This makes even the OTP (one-time programmable) property of most Padauk MCUs less significant than one might at first assume.

Then there’s the actual programming of the MCUs. The Micro C compiler Padauk provides essentially implements a sub-set of the C language, with some macros to replace things like for loops. Initially this may seem like a weird limitation, until you realize that these MCUs have 64 to 256 bytes of SRAM. That’s bytes, without any prefixes.

Finally, [Jay] shows off a couple of test projects, including a NeoPixel SPI adapter and bike light, which are all available on Github. The WS2812b project is something we have seen before, for example this project from [Anders Nielsen] (featured in the article image), which provides another take on this range of MCUs.

Did reading [Jay]’s article change your mind on these Padauk parts? Have you used these MCUs and ICE parts before? Feel free to leave your thoughts in the comments.

The Ultimate Guide To Artisan USB Cables

September 4, 2019 by Tom Nardi 45 Comments

If you’ve gone through the trouble of building your own customized mechanical keyboard, the last thing you want to do is plug it into your computer with some plebeian USB cable from the local electronics shop. Your productivity, nay livelihood, depends on all those 1s and 0s being reproduced with the crisp fidelity that’s only possible with a high-end USB cable. Anything less would be irresponsible.

Or at least, that’s what the advertising on the back of the package would say if we tried to sell the custom USB cables built by [Josef Adamčík]. But alas, he’s decided to give away all the details for free so that anyone can build their own delightfully overengineered USB cables. Do you need a paracord USB cable with GX12 aviation connectors in the middle? Of course not. But you still want one, don’t you?

As [Josef] admits in his blog post, there’s nothing particularly special about what he’s doing here. If you can splice wires together, you can build your own bespoke USB cables. But what attracted us to his write-up was the phenomenal detail he goes into. Every step is clearly explained and includes a nice, well-lit, photo to illustrate what he’s doing. Honestly, when the documentation for soldering some USB connectors onto a wire looks this good, there’s no excuse why more substantial projects get little more than a few blurry shots.

Of course, even for those of us who are no stranger to the ways of the soldering iron, there’s likely a few ideas you can pull from this project. We particularly liked his tip for taping the USB connector to the workbench while soldering it rather than trying to get it to stay in a vise, and his method for adding a coil the cable with a wooden jig and a heat gun is definitely something to file away for future use.

Then again in an era where even the lowly-USB cable can potentially be a security threat, or simply not live up to published specifications, rolling your own might not be such a bad idea.

(Mis)use This Part To Attach 3D Printed Stuff To A Shaft

September 2, 2019 by Donald Papp 16 Comments

Interfacing a shaft to a 3D printed gear doesn’t have to be tricky. [Tlalexander] demonstrated a solution that uses one half of a spider coupling (or jaw coupling) to create an effective modular attachment. The picture above (and this older link) shows everything you need to know: the bottom of the coupling is mounted to the shaft, and a corresponding opening is modeled into the the 3D printed part. Slide the two together, and the result is a far sturdier solution than trying to mate a 3D printed gear directly to a motor shaft with a friction fit or a screw. This solution isn’t necessarily limited to attaching gears either, any suitable 3D printed part could be interfaced to a shaft in this way.

These couplings are readily available, and fortunately for hobbyists, come in sizes specifically designed for common stepper motors like NEMA 17 and NEMA 23. Ironically, these couplings are often used when building custom 3D printers for those same reasons. With this method interfacing anything at all to a motor shaft becomes mostly a matter of modeling a matching hole out of the part to be 3D printed. One coupling even provides two such attachments, since only one of the two sides is used.

The image up top is from [Tlalexander]’s Rover image gallery, which contains a ton of fantastic pictures of the work that went into the gearboxes, a major part of the Rover’s design that we’ve seen in the past.

Stack Of Plant Saucers, Transformed Into Low Cost Solar Shield

September 1, 2019 by Donald Papp 12 Comments

For serious data collection with weather sensors, a solar shield is crucial. The shield protects temperature and humidity sensors from direct sunlight, as well as rain and other inclement weather, without interfering with their operation. [Mare] managed to create an economical and effective shield for under three euros in materials.

It began with a stack of plastic saucers intended for the bottom of plant pots. Each of these is a lot like a small plate, but with high sides that made them perfect for this application. [Mare] cut the bottom of each saucer out with a small CNC machine, but the cut isn’t critical and a hand tool could also be used.

Three threaded rods, nuts, and some plastic spacers between each saucer yields the assembly you see here. When mounted correctly, the sensors on the inside are protected from direct exposure to the elements while still allowing airflow. As a result, the readings are more accurate and stable, and the sensors last longer.

The top of the shield is the perfect place to mount a UV and ambient light sensor board, and [Mare] has a low-cost DIY solution for that too. The sensor board is covered by a clear glass dish on top that protects the board without interfering with readings, and an o-ring seals the gap.

3D printing is fantastic for creating useful components, and has been instrumental in past weather station builds, but projects like these show not everything needs to be (nor should be) 3D printed.

Everything You Want To Know About The Cheapest Processors Available

August 28, 2019 by Jenny List 48 Comments

Those of us who use microprocessors in our work will be familiar with their cost, whether we are buying one or two for a project or ten million on reels for a production run. We’re used to paying tens of cents or maybe even a dollar for a little microcontroller in single quantities, and these are probably the cheapest that we might expect to find.

There is a stratum of cheaper devices though, usually from Chinese manufacturers with scant data in English and difficult to source in Europe or the Americas. These chips cost under ten cents each, a figure which seems barely credible. To shed some light upon this world, [cpldcpu] has produced a run-down of some of the available families that even if you will never work with such an inexpensive option still makes for a fascinating read.

These processors are not the type of component you would use for high intensity tasks so it’s probable that you will not be mining cryptocurrency on a brace of them. Thus their architecture is hardly cutting-edge, with the venerable PIC12 being their inspiration and in some cases their direct copy. These are all write-once devices and some of their toolchains are variable in accessibility, but perhaps they aren’t as terrible as some would have you believe. If you are looking for inspiration, we’ve featured one of them before.

TL;DR: the Padauk PFS173, at just under $0.09, has an open-source toolchain and a decent set of peripherals.

Thanks [WilkoL] for the tip.

Image: A real PIC12 die shot. ZeptoBars [CC BY 3.0]