Mysterious Files PH

If you want to get around Monaco, a map — digital or otherwise — is probably the best way to navigate. But if you just want to appreciate the city’s form in a more artistic way, you might enjoy [Terence Grover’s] latest project—a backlit topographic map of the unique principality.

The project started with a QGIS mesh of Monaco, with the data fed through the Open-Meteo elevation API, which takes into account building heights. This was used as the basis for the heights of 179 pieces of 20 mm x 20 mm acrylic. These were assembled into a laser cut steel base, and were sanded on all sides but the base in order to allow them to diffuse light more effectively.

Strips of CS8812 LEDs are used to light the plastic towers, driven by a pair of Adafruit Feather RP2040 Scorpio boards. They’re fed pixel data from a Raspberry Pi 5, which runs a Flask panel accessed over an iPad. This allows control over the LED map display, showing things like civic data, highlighted events, and weather. There’s even a touch-sensitive mode that lets one paint fun patterns across the representation of the city.

We love a good artistic map, particularly when they’re full of LEDs and represent useful information.

We’re all used to satellite navigation systems such as GPS or GLONASS, sheer magic in which the combination of a set of reference transmitters and super-accurate timing information can be used to calculate a position to an astounding precision. They had land based predecessors such as LORAN and Decca Navigator which worked in a similar fashion but with fixed land-based reference transmitters. Terra is an attempt to do the same thing without a network of dedicated transmitters, instead using FM broadcast transmitters as its fixed points.

This might seem like an impossible task without access to the transmitters, but they have a workaround using the Internet as a backhaul. Instead of transmitting their timing information like the systems mentioned above, they rely on a set of reference receivers sharing it online to the client’s receiver software. So far they have a demo running in Denver.

The interesting thing about this system is that it’s open-source, and requires only a relatively inexpensive software defined radio receiver and a computer to operate. Now anyone with a group of internet-connected friends to set up reference receivers can have their own positioning system, it’s no longer the exclusive preserve of governments. We like this idea, and we look forward to seeing it being tested more widely.

If you’d like to know where we’ve come from, we’ve taken a look at LORAN before.

This week Jonathan chats with Andy Gryc and Aaron Basset about QNX, and the interesting Open Source history and future of that embedded OS. Why does QNX Everywhere feel more open, and why do you need to register an account to download images? All that and more — Watch to find out!

• Open-source Dashboard: https://oss.qnx.com/
• GitHub Repository: https://github.com/qnx-ports
• QNX Everywhere webpage: https://qnx.software/en/developers/get-started/qnx-everywhere

Did you know you can watch the live recording of the show right on our YouTube Channel? Have someone you’d like us to interview? Let us know, or have the guest contact us! Take a look at the schedule here.

Direct Download in DRM-free MP3.

If you’d rather read along, here’s the transcript for this week’s episode.

Theme music: “Newer Wave” Kevin MacLeod (incompetech.com)

Licensed under Creative Commons: By Attribution 4.0 License

About 18 months ago, we brought you a sneak peek at a handheld that started life in the Dutch conference badge scene. At the time it showed promise, but its software wasn’t ready for a fair review. Now it has both a stable operating system and a growing software library. It’s time to put it through its paces and see what it can do.

A Handheld Computer For Hackers

The Tanmatsu (Japanese for “Terminal”), is a general putpose palmtop computer based around an ESP32-P4 application processor from Espressif. It takes the form of a PCB and PETG 3D printed sandwich, with the front face PCB sporting a silicone QWERTY keyboard and an 800×480 MIPI DSI display. The keyboard should be familiar to many readers, being the same moulding as the Solder Party KeebDeck which has appeared on other devices.

Under the hood that P4 has two 400MHz RISC-V cores and 32MB of PSRAM with 16MB of Flash, and there’s an ESP32-C6 for WiFi, BLE and IEEE 802.15.4 mesh networking. There’s an Ebyte LoRa module with an SMA antenna too, which can be had in 868, or 915MHz versions depending on where in the world you live.

For interfacing there are USB A and C ports, and SD card socket, a 3.5 mm jack for audio, and three expansion ports. On the right side a Qwiic compatible socket, on the left a socket with PMOD and SAO capabilities, and on the rear under the cover, a CSI camera connector the same as the Raspberry Pi, and a much larger expansion socket with all the various signals, planned for add-ons. It’s all powered by a chunky 2500 mAh LiPo which can be charged through the USB-C port.

Because I know the folks behind it I’ve watched it grow from its origins in a souped-up version of the MCH2022 badge into its current form, indeed I bought my Tanmatsu just over a year ago. Due to those origins in the Dutch badge team, this device is open-source. The Tanmatsu is a commercial version produced and sold by Renze Nicolai, its designer, while the Konsool is its community cousin. You can find its mechanical hardware here, its electronics here, and its firmware here.

An App Repository For Your Creations

Turning the Tanmatsu on, after a synthwave-inspired splash screen you find yourself in a graphical menu. The user interface is pretty intuitive to anyone used to a desktop GUI or a modern smartphone, along the top are status icons for SD card, Wi-Fi, and battery, the main body of the screen has a grid of icons, and along the bottom is a list of the various keyboard shortcuts. Navigation is via a set of arrow keys with the return key selecting an option, and a set of coloured function keys handle special functions.

On first start-up the Tanmatsu has no apps installed, so the first order of business is to connect to a Wi-Fi network and update the firmware through the Settings. It takes a while to do this as it can update the firmware on the P4, the C6, and the microcontroller it uses for housekeeping. A feature I like is that this is the first device from the world of badges I’ve seen that can hold more than one set of Wi-Fi network details rather than requiring me to change the settings at each location.

With a freshly updated Tanmatsu you can open the repository, this device’s app store, and download some apps to get started. This is a long-standing badge.team feature, in that badges going back to their SHA 2017 offering have had downloadable apps. The apps are sorted into categories for easy navigation, and in my case there are immediately two apps I have installed, the Tamatype camera app for my Pi camera add-on, and from the choice of two different Meshcore apps, Wadamesh.

The apps themselves come in two forms, either ones written in an interpreted scripting language such as MicroPython, or those compiled directly for the P4. It doesn’t ship with a script engine installed, however MicroPython is downloadable as an app from the repository. This is not a multitasking device so the front-end is a launcher, and after running an app the screen will flash blue for a moment as it loads. Each app has a metadata file which instructs the Tanmatsu what to do with it, an icon file, and a folder containing its executable components. There’s a comprehensive online guide, should you wish to try developing your own apps.

In use the Tanmatsu is convenient to hold and type with using two hands. The display is clear and bright, and the keyboard while a little on the small side has a positive click action. Using the apps depends on the individual choices of the app developer, but the interface conventions are straightforward. I’ve been using it for Meshcore for a while now, and it makes a very handy terminal indeed.

In A Niche Of Its Own

The price of a fully assembled Tanmatsu is 99 Euros, plus Dutch sales tax if you live in the EU, and shipping. The good news for Americans in an age of uncertain tariffs is that I’m told they will be shipping from a US warehouse in the next few months. It’s worth considering for a moment where this places the device in the ecosystem of similar computers.

It’s relatively simple to make a handheld Linux cyberdeck using a Raspberry Pi board, however once the price of new peripherals and parts is taken into account it’s not necessarily a cheap project. There are quite a few similar-sized Linux devices on the market whose prices reflect this at about twice as much. Thus I think that the Tanmatsu fits in a middle zone between development boards that come without the screen, battery, and keyboard, and those Linux handhelds that are all-singing all-dancing.

In its favour it’s as far as I know the only P4 device on the market with a mature operating system and particuarly an app repository, but if only Linux will do, it’s unable to deliver. Where I think its niche lies is in being simple and low power enough to be a reliable and powerful hacker’s communicator and general purpose toolkit, but cheap enough to remain a reasonable purchase. For now it stands alone in that niche, and only time will tell whether it can successfully define it.

Everybody loves aquariums. There’s something soothing about watching the lil’ critters inside them swimming, crawling and wriggling about. But at the same time few people are up to the task of ensuring that said critters stay alive and happy in said aquarium. This is where small robots may be able to steal some fishy jobs, like a modern take on the gaudy fake aquariums of the 1990s. Cue [CPSDrone]’s mini-drone aquarium with mostly maintenance-free robotic fish.

These pose a few interesting engineering challenges, such as the replacing of feeding fish by having them scuttle back to their charging station like an aquatic Roomba, and giving them some level of intelligence to the point that they at least appear to be doing something fish-like.

Rather than give each robot fish full autonomy, they are instead controlled by a central system. This then raised the problem of radio frequency communication while underwater. The theory was that 433 MHz transceivers would still work for something the size of an aquarium before attenuation spoils things, which a quick test confirmed to be true.

This enabled the construction of a small microcontroller-carrying submarine as a proof of concept before diving into the final version, involving resin 3D printed enclosures that are made water-tight using rubber O-ring seals and UV-cured resin. All that was left now was to add the big control system, which takes up much of the rest of the video.

Sadly they didn’t implement the boids algorithm, as this is pretty good at creating realistic life-like motion, as show with this demonstration by [Ben Eater]. This algorithm is pretty simple, with each ‘creature’ obeying rules on coherence, separation and alignment, creating a pattern that can be observed among schools of fish as well as flocks of birds. Due to its simplicity you could conceivably even omit the central control system and just give each ‘fish’ enough sensors to keep track of its buddies.

The phenomenon of cable-shaped indents in the plastic cases of retro systems is one that’s probably painfully familiar to many a collector of such systems. Although in these situations neither side got hot enough to cause any melting – especially while disconnected in storage – it still has that same melted appearance. The real cause here is not heat, but plasticizer migration, as detailed in a recent video by [Run Stop Restored] over on YouTube.

Plasticizers are an additive to many plastics that aim to make it more flexible (‘plastic’), as well as improve other characteristics of the base material, with PVC in particular relying on plasticizers to give it its desired properties for applications where PVC has to be flexible. Here the flexible cable insulation of these devices generally uses PVC, which over time can migrate to other polymers when brought into close contact for extended periods of time.

The – usually ABS – enclosures of e.g. Commodore tape drives as in this video demonstration thus get correspondingly inundated with the same type of plasticizers that ABS is also highly susceptible to. Since in storage the cables tend to be wrapped – tightly – around the device they’re attached to, this results in a solid contact which thus enables this gradual process to work its magic, whether it’s a Commodore datasette or a power supply brick.

Correspondingly the PVC insulation becomes brittle as it loses its plasticizer, with the process sped up by higher environmental temperatures. To prevent this, never wrap a PVC cable around a device, and keep it physically separated from susceptible plastics like ABS as much as reasonably possible. Along with a cool environment this should prevent plasticizer migration from ruining what used to be a pristine case.

This problem is particularly significant for retro gear from the 1980s and thereabouts, before phthalate-free plasticizer alternatives were developed, along with other changes such as more stable formulations that prevent this migration process. Adding a coating can also help, especially for protecting older gear, but flexible PVC in particular should be viewed with suspicion and treated carefully.

Every experienced machinist knows the value of taking regular measurements. If one works carefully and checks dimensions frequently, it’s possible to make a part much more precise than could be made by relying on the machine’s accuracy alone. In a similar vein, it’s possible to make a measuring device out of comparatively crude parts, as long as their behavior is well understood. Related to both principles is [BubsBuilds]’s displacement sensor, which uses a 3D printed frame but reaches precision better than two micrometers.

Admittedly the printed parts aren’t the source of the sensor’s precision, that comes from an opto-interrupter. This design has a central stylus, one end of which contacts the object under measurement. The other end flattens to a knife-edge blade, which fits between the diodes of the opto-interrupter. As the stylus point is pressed in, the blade blocks off more light from reaching the photodiode, creating an output signal proportional to displacement. To keep the stylus from twisting or moving side-to-side, two flat, circular flexures hold the stylus in the center of a cylindrical housing.

[Bubs] printed several flexure variations to see how well they resisted and permitted various torques and forces, and a symmetrical flexure design proved best for his purposes. Once the sensor was assembled, he tested it against the measurements recorded by a laser confocal displacement sensor. This design was an update from a previous version, and it improved in a few regards: the non-linearity had decreased, and the repeatability was now better than two microns, though the range had been halved. Significantly, though, it’s now much easier to mount, making this an actually practical tool.

If, however, this doesn’t fit your needs, there are many other ways to build a linear displacement sensor, ranging from capacitive to magnetostrictive. On the manual side of things, we’ve also covered a comparison of calipers.