Bare-Metal STM32: Exploring Memory-Mapped I/O And Linker Scripts

December 23, 2020 by 19 Comments

In the first installment of this series we had a brief look at the steps needed to get a bare-metal application running on an STM32 microcontroller. While this allowed us to quickly get to the juicy stuff, there are two essential elements which make an MCU so easy to use. One is found on the hardware side, in the form of so-called memory-mapped I/O (input/output), the other is the information contained in the files that are passed to the linker when we build a firmware image.

Memory-mapping of hardware peripheral registers is a straightforward way to make them accessible to the processor core, as each register is accessible as a memory address. This is both convenient when writing the firmware code, as well as for testing, as we can use a memory mapping specific for unit or integration testing.

We will take an in-depth look at this way of testing, as well as how these linker script files are connected to the memory layout. Continue reading “Bare-Metal STM32: Exploring Memory-Mapped I/O And Linker Scripts” →

For Your Holiday Relaxation: The Clickspring Sundial Build Megacut

December 23, 2020 by 7 Comments

The fortunate among us may very well have a bit of time off from work coming up, and while most of that time will likely be filled with family obligations and festivities, there’s probably going to be some downtime. And if you should happen to find yourself with a half hour free, you might want to check out the Clickspring Byzantine Calendar-Sundial mega edit. And we’ll gladly accept your gratitude in advance.

Fans of machining videos will no doubt already be familiar with Clickspring, aka [Chris], the amateur horologist who, through a combination of amazing craftsmanship and top-notch production values, managed to make clockmaking a spectator sport. We first caught the Clickspring bug with his open-frame clock build, which ended up as a legitimate work of art. [Chris] then undertook two builds at once: a reproduction of the famous Antikythera mechanism, and the calendar-sundial seen in the video below.

The cut condenses 1,000 hours of machining, turning, casting, heat-treating, and even hand-engraving of brass and steel into an incredibly relaxing video. There’s no narration, no exposition — nothing but the sounds of metal being shaped into dozens of parts that eventually fit perfectly together into an instrument worthy of a prince of Byzantium. This video really whets our appetite for more Antikythera build details, but we understand that [Chris] has been busy lately, so we’ll be patient.

Continue reading “For Your Holiday Relaxation: The Clickspring Sundial Build Megacut” →

The Mouth-Watering World Of NIST Standard Foods

December 23, 2020 by 48 Comments

The National Institute Of Standards and Technology was founded on March 3, 1901 as the National Bureau of Standards, taking on its current moniker in 1988. The organisation is charged by the government with ensuring the uniformity of weights and measures across the United States, and generally helping out industry, academia and other users wherever some kind of overarching standard is required.

One of the primary jobs of NIST is the production and sale of Standard Reference Materials, or SRMs. These cover a huge variety of applications, from steel samples to concrete and geological materials like clay. However, there are also edible SRMS, too. Yes, you can purchase yourself a jar of NIST Standard Peanut Butter, though you might find the price uncompetitive with the varieties at your local supermarket. Let’s dive into why these “standard” foods exist, and see what’s available from the shelves of our favourite national standards institute. Continue reading “The Mouth-Watering World Of NIST Standard Foods” →

Hyundai Mini 45 EV Is A Small Car With Grand Ambitions

December 23, 2020 by 20 Comments

One of Hyundai’s recent concept cars was an electric vehicle named “45” in honor of its inspiration, another concept car from 45 years ago. When footage of a child-sized “Mini 45” surfaced, it was easy to conclude the car was a motorized toy for children. But Jalopnik got more information from Hyundai about this project, where we learned that was not nearly the whole picture.

The video (embedded below) explained this little vehicle is a concept car in its own right, and most of the video is a scripted performance illustrating their concept: using technology to help calm young patients in a hospital, reducing their anxiety as they faced treatment procedures. Mini 45 packs a lot more equipment than the toy cars available at our local store. The little driver’s heartbeat and breathing rate are monitored, and a camera analyzes facial expressions to gauge emotional stress. The onboard computer has an animated avatar who will try to connect with the patient, armed with tools like colorful animations, happy music, candy scent dispenser, and a bubble-blowing machine.

Continue reading “Hyundai Mini 45 EV Is A Small Car With Grand Ambitions” →

A Tiny LED Matrix Is Better With Friends

December 23, 2020 by 8 Comments

When we last heard from [lixielabs] he was building Nixie tube replacements out of etched acrylic and LEDs. Well he’s moved forward a few decades to bring us the Pixie, a chainable, addressable backpack for tiny LED matrix displays.

Each Pixie module is designed to host two gorgeous little Lite-On LTP-305G/HR 5×7 LED dot matrix displays, which we suspect have been impulse purchases in many a shopping cart. Along with the displays there is a small matrix controller and an ATTINY45 to expose a friendly electrical interface. Each module is designed to be mounted edge to edge and daisy chained out to 12 or more (with two displays each) for a flexible display any size you need. But to address the entire array only two control pins are required (data and clock).

[lixielabs] has done the legwork to make using those pins as easy as possible. He is careful to point out the importance of a good SDK and provides handy Arduino libraries for common microcontrollers and a reference implementation for the Raspberry Pi that should be easy to crib from to support new platforms. To go with that library support is superb documentation in the form of a datasheet (complete with dimensions and schematic!) and well stocked GitHub repo with examples and more.

To get a sense of their graphical capabilities, check out a video of 6 Pixie’s acting as a VU meter after the break. The Pixie looks like what you get when a hacker gets frustrated at reinventing LED dot matrix control for every project and decided to solve it once and for all. The design is clean, well documented, and extremely functional. We’re excited to see what comes next! Continue reading “A Tiny LED Matrix Is Better With Friends” →

The World Is Your Green Screen

December 22, 2020 by 9 Comments

This year has been the year of home video conferencing. If you are really on the ball, you’ve managed to put some kind of green screen up so you can hide your mess and look as though you are in your posh upper east side office space. However, most of the consumer video conferencing now has some way to try to guess what your background is and replace it even without a green screen. The results, though, often leave something to be desired. A recent University of Washington paper outlines a new background matting procedure using machine learning and, as you can see in the video below, the results are quite good. There’s code on GitHub and even a Linux-based WebCam filter.

The algorithm does require a shot of the background without you in it, which we imagine needs to be relatively static. From watching the video, it appears the acid test for this kind of software is spiky hair. There are several comparisons of definitely not bald people flipping their hair around using this method and other background replacers such as the one in Zoom.

Continue reading “The World Is Your Green Screen” →

Adding Space Music To The Astronomy Toolbox

December 22, 2020 by 4 Comments

Astronomy fans were recently treated to the Great Conjunction, where Jupiter and Saturn appear close together from the perspective of our planet Earth. Astronomy has given us this and many other magnificent sights, but we can get other senses involved. Science News tells of explorations into adapting our sense of hearing into tools of astronomical data analysis.

Data visualization has long been a part of astronomy, but they’re not restricted to charts and graphs that require a trained background to interpret. Every “image” generated using data from radio telescopes (like the recently-lost Arecibo facility) are a visualization of data from outside the visible spectrum. Visualizations also include crowd pleasing false-color images such as The Pillars of Creation published by NASA where interstellar emissions captured by science instruments are remapped to colors in the visible spectrum. The results are equal parts art and science, and can be appreciated from either perspective.

Data sonification is a whole other toolset with different strengths. Our visual system evolved ability to pick out edges and patterns in spatial plots, which we exploit for data visualization. In contrast our aural system evolved ability to process data in the frequency domain, and the challenge is to figure out how to use those abilities to gain scientifically relevant data insight. For now this field of work is more art than science, but it does open another venue for the visually impaired. Some of whom are already active contributors in astronomy and interested in applying their well-developed sense of hearing to their work.

Of course there’s no reason this has to be restricted to astronomy. A few months ago we covered a project for sonification of DNA data. It doesn’t take much to get started, as shown in this student sonification project. We certainly have no shortage of projects that make interesting sounds on this site, perhaps one of them will be the key.