Pi Microcontroller Still Runs A Webserver

At first glance, the Raspberry Pi Pico might seem like a bit of a black sheep when compared to the other offerings from the Raspberry Pi Foundation. While most of the rest of their lineup can run Linux environments with full desktops, the Pico is largely limited to microcontroller duties in exchange for much smaller price tags and footprints. But that doesn’t mean it can’t be coerced into doing some of the things we might want a mainline Pi to do, like run a web server.

The project can run a static web page simply by providing the Pico with the project code available on the GitHub page and the HTML that you’d like the Pico to serve. It can be more than a static web page though, as it is also capable of running Python commands through the web interface as well. The server can pass commands from the web server and back as well, allowing for control of various projects though a browser interface. In theory this could be much simpler than building a physical user interface for a project instead by offloading all of this control onto the web server instead.

The project not only supports the RP2040-based Raspberry Pi Pico but can also be implemented on other WiFi-enabled microcontroller boards like the ESP8266 and ESP32. Having something like this on hand could greatly streamline smaller projects without having to reach for a more powerful (and more expensive) single-board computer like a Pi 3 or 4. We’ve seen some other builds on these boards capable of not only running HTML and CSS renderers, but supporting some image formats as well.

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Balancing A Motor With An Oscilloscope

With all things in life, one must seek to achieve balance. That may sound a little like New Age woo-woo, but if you think it’s not literally true, just try tolerating a washing machine with a single comforter on spin cycle, or driving a few miles on unbalanced tires.

Anything that rotates can quickly spin itself into shrapnel if it’s not properly balanced, and the DIY power tools in [Matthias Wandel]’s shop are no exception. Recent upgrades to his jointer have left the tool a bit noisy, so he’s exploring machine vibrations with this simple but clever setup. Using nothing but a cheap loudspeaker and an oscilloscope, [Matthias] was able to characterize vibrations in a small squirrel-cage blower — he wisely chose to start small to validate his method before diving into the potentially dangerous jointer. There was quite a lot to be learned from the complex waveforms coming back from the transducer, analysis of which was greatly helped by the scope’s spectrum analyzer function. The video below shows the process of probing various parts of the blower, differentiating spectral peaks due to electrical noise rather than vibration, and actually using the setup to dynamically balance the fan.

We’d rate this as yet another handy shop tip from [Matthias], and we’ll be looking out for the analysis of his jointer. Want to do the same but you don’t have an oscilloscope? No problem — an earbud and Audacity might be all you need.

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SmallKat: An Adorable And Dynamic Robot

SmallKat is a cute little robot with a lot of capability designed around teaching and experimenting with dynamic robot control. It’s a shame we haven’t covered SmallKat yet, as it’s both a finalist in the 2019 Hackaday Prize and was one of the Bootstrap Winners this year.

Many hobby robots move by repeating a pre-programmed sequence of movements. Most hexapods for example follow this line of thought. However, robots like Spot and the MiniCheetah show a different world where robots determine the locations of their limbs by their current state, the measured state of their environment, and some imagined future. These robots are capable of so much more than their predecessors.

However, even a cost-effective version of these robots climb into the tens of thousands of dollars at a steep curve. SmallKat will help there: based around hobby servos and an ESP32 the hardware stays affordable. Data can be streamed to a much larger computer for experimentation which saves on some of the weight that supporting a larger device like a Pi would add.

This device will let students experiment with all kinds of dynamic models and even machine learning-based movements without breaking the bank. There’s even a nice software studio for experimentation to aid in the learning process.  Video of it shuffling around after the break.

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DIY Ribbon Element Upgrades A Studio Microphone

For those with some experience with pro audio, the term “ribbon microphone” tends to conjure up an image of one of those big, chunky mics from the Golden Age of radio, the kind adorned with the station’s callsign and crooned into by the latest heartthrob dreamboat singer. This DIY ribbon mic is none of those things, but it’s still really cool.

Of course the ribbon mic isn’t always huge, and the technology behind it is far from obsolete. [Frank Olsen]’s ribbon mic starts out with gutting a run-of-the-mill studio mic of its element, leaving only the body and connector behind. The element that he constructs, mostly from small scraps of aluminum and blocks of acrylic, looks very much like the ribbon element in commercial mics: a pair of magnets with a thin, corrugated strip of foil suspended between them. The foil was corrugated by passing it through a jig that [Frank] built, which is a neat tool, but he says that a paper crimper used for crafting would work too. There’s some pretty fussy work behind the cartridge build, but everything went together and fit nicely in the old mic body. The video below was narrated using the mic, so we know it works.

Fun fact: the ribbon microphone was invented by Walter Schottky. That Walter Schottky. Need more on how these mics work? Our colleague [Al Williams] has you covered with this article on the basics.

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Dynamic Bicycle Headlight Uses The Open Road As A Display

This thing is so cool it almost looks fake. But [Matt Richardson] isn’t a hoaxster. He actually built what might be called a heads-down display for your bicycle. He refers to it as a headlight because it borrows a similar function. It mounts on the handlebars and shoots light off the front of the bike. But it’s more than just a battery and a bulb, this uses a pico-projector to give that light some meaning. In the video after the break he shows it off on the streets of NYC.

So far he’s only displaying information that has to do with the speed of travel, but the proof is there just waiting for a brilliant new use. Feeding the projector is a Raspberry Pi board. For this prototype [Matt] mounted it, along with the portable cellphone charger which plays the role of the power source, on a hunk of hardboard strapped inside the bike frame.

If you’re thinking of doing this one yourself beware of the BOM price tag. That projector he’s using runs upwards of $400. We wonder if you could hack together a rudimentary replacement with an old cellphone screen and this diy film projector?

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Surviving A Hacker Conference


With another hacker conference looming in front of us, it’s time to start thinking about hardware security. Hacker conventions have the most hostile network you’ll ever encounter. [Security4all] points out that 25C3 already has an extensive page on securing your hardware. It starts from the ground up with physical security, BIOS passwords, and locking down bootloaders. There’s a section on securing your actual OS and session. Finally, they cover network usage. It mentions using SSH for dynamic forwarding, which we feel is a skill everyone should have. We’ve used it not just for security, but for bypassing brainless bandwidth restrictions too. There’s also the more trick transparent version. Every piece of data you bring with you, you risk losing, so they actually recommend just wiping your iPhone and other devices before attending. It’s important to remember that it’s not just your own data at risk, but everyone/thing you communicate with as well.