Month: September 2020

A Free Software OS For The ReMarkable E-Paper Tablet

September 6, 2020 by 83 Comments

If you’re looking to rid your day to day life of dead trees, there’s a good chance you’ve already heard of the reMarkable tablet. The sleek device aims to replace the traditional notebook. To that end, remarkable was designed to mimic the feeling of writing on actual paper as closely as possible. But like so many modern gadgets, it’s unfortunately encumbered by proprietary code with a dash of vendor lock-in. Or at least, it was.

[Davis Remmel] has been hard at work porting Parabola, a completely free and open source GNU/Linux distribution, to the reMarkable. Developers will appreciate the opportunity to audit and modify the OS, but even from an end-user perspective, Parabola greatly opens up what you can do on the device. Before you were limited to a tablet UI and a select number of applications, but with this replacement OS installed, you’ll have a full-blown Linux desktop to play with.

You still won’t be watching videos or gaming on the reMarkable (though technically, you would be able to), but you could certainly use it to read and edit documents the original OS didn’t support. You could even use it for light software development. Since USB serial adapters are supported, microcontroller work isn’t out of the question either. All while reaping the considerable benefits of electronic paper.

The only downside is that the WiFi hardware is not currently supported as it requires proprietary firmware to operate. No word on whether or not [Davis] is willing to make some concession there for users who aren’t quite so strict about their software freedoms.

We’ve been waiting patiently for the electronic paper revolution to do more than replace paperbacks with Kindles, and devices like the reMarkable seem to be finally moving us in the right direction. Thankfully, projects that aim to bring free and open source software to these devices mean we won’t necessarily have to let Big Brother snoop through our files in the process.

Filament Dust Filter Helps Keep Your Print Quality High

September 6, 2020 by 19 Comments

If we’re honest, our workshop isn’t as clean as it probably should be, and likely many makers out there will say the same. This can have knock-on effects, such as iron filings clogging motors, or in this case, dust affecting the quality of 3D prints. Aiming to tackle this, [3Demon] built a fun Spongebob-themed dust filter for their 3D printer.

The filter works in a simple way. The Spongebob shell is 3D printed in two halves, with a hinge joining both parts. Inside each half, a section of sponge is stuck inside. The two halves are then closed with a snap fit, with the filament passing through a hole in Spongebob’s head and out through the (square) pants. With the sponge packed in nice and tight, dust is wiped from the filament as it feeds through bob to the printer.

While it’s important to install carefully to avoid filament feed issues, it’s an easy way to automatically clean filament during the printing process. You may be surprised just how dirty your filament gets after sitting on the shelf for a few months. Getting rid of such contamination decreases the likelihood of annoying problems like delaminations and jams. Avid printers may also want to consider making their own filament, too. Happy printing!

ExoMy Is A Miniature European Mars Rover With A Friendly Face

September 5, 2020 by 5 Comments

Over the past few weeks, a new season of Mars fever kicked off with launches of three interplanetary missions. And since there’s a sizable overlap between fans of spaceflight and those of electronics and 3D printing, the European Space Agency released the ExoMy rover for those who want to experience a little bit of Mars from home.

ExoMy’s smiling face and cartoonish proportions are an adaptation of ESA’s Rosalind Franklin (formerly the ExoMars) rover which, if 2020 hadn’t turned out to be 2020, would have been on its way to Mars as well. While Rosalind Franklin must wait for the next Mars launch window, we can launch ExoMy missions to our homes now. Like the real ESA rover, ExoMy has a triple bogie suspension design distinctly different from the rocker-bogie design used by NASA JPL’s rover family. Steering all six wheels rather than just four, ExoMy has maneuvering chops visible in a short Instagram video clip (also embedded after the break).

ExoMy’s quoted price of admission is in the range of 250-500€. Perusing instructions posted on GitHub, we see an electronics nervous system built around a Raspberry Pi. Its published software stack is configured for human remote control, but as it is already running ROS (Robot Operating System), it should be an easy on-ramp for ExoMars builders with the ambition of adding autonomy.

ExoMy joins the ranks of open source rover designs available to hackers with 3D printing, electronics, and software skills. We recently covered a much larger rover project modeled after Curiosity. Two years ago NASA JPL released an open source rover of their own targeting educators, inspiring this writer’s own Sawppy rover project, which is in turn just one of many projects tagged “Rover” on Hackaday.io. Hackers love rovers!

Building A UV Curing Station For Resin Prints

September 5, 2020 by 10 Comments

Resin printers have a lot going for them – particularly in regards to quality surface finishes and excellent reproduction of fine details. However, the vast majority rely on UV light to cure prints. [douwe1230] had been using a resin printer for a while, and grew tired of having to wait for sunny days to cure parts outside. Thus, it was time to build a compact UV curing station to get the job done.

The build consists of a series of laser-cut panels, assembled into a box one would presume is large enough to match the build volume of [douwe1230’s] printer.  UV LED strips are installed in the corners to provide plenty of light, and acrylic mirrors are placed on all the walls. The use of mirrors is key to evenly lighting the parts, helping to reduce the likelihood of any shadows or dead spots stopping part of the print from curing completely. In the base, a motor is installed with a turntable to slowly spin the part during curing.

[Douwe1230] notes that parts take around about 10 minutes to cure with this setup, and recommends a flip halfway through to make sure the part is cured nice and evenly. We’ve seen other similar DIY builds too, like this one created out of a device aimed at nail salons. If you’re struggling with curing outside, with the weather starting to turn, this might just be the time to get building!

Intuition About Signals And Systems

September 5, 2020 by 7 Comments

Signals and systems theory is a tough topic. Terms like convolution and impulse response can be hard to understand on a visceral level and most books that talk about these things emphasize math over intuition. [Discretised] has a YouTube channel that already has several videos that promise to tackle these topics with “minimum maths, maximum intuition.” We particularly noticed the talks on convolution and impulse response.

We think that often math and intuition don’t always come together. It is one thing, for example, to know that E=I times R, and power is I times E, but it is another to realize that a half-watt transmitter delivers 5V into a 50Ω load and that one watt will take just over 7V into that same load.

The example used is computing how much smoke you can expect to create by setting off fireworks. We presume the math models are notional since we imagine a real model would be pretty complex and involve things like wind data. But it still makes a nice example.

If you don’t know anything about the topic, these might not be the right ones to try to learn the basics. But we do applaud people sharing their intuition on these complex subjects.

Continue reading “Intuition About Signals And Systems” →

Turning The Raspberry Pi Into A MCU Programmer

September 5, 2020 by 42 Comments

Once you graduate beyond development boards like the Arduino or Wemos D1, you’ll find yourself in the market for a dedicated programmer. In most cases, your needs can be met with a cheap USB to serial adapter that’s not much bigger than a flash drive. The only downside is that you’ve got to manually wire it up to your microcontroller of choice.

Unless you’re [Roey Benamotz], that is. He’s recently created the LEan Mean Programming mAchine (LEMPA), an add-on board for the Raspberry Pi that includes all the sockets, jumpers, and indicator LEDs you need to successfully flash a whole suite of popular MCUs. What’s more, he’s written a Python tool that handles all the nuances of getting the firmware written out.

After you’ve configured the JSON file with the information about your hardware targets and firmware files, they can easily be called up again by providing a user-defined ID name. This might seem overkill if you’re just burning the occasional hex, but if you’re doing small scale production and need to flash dozens of chips, you’ll quickly appreciate a little automation in your process.

Of course, if you’re just trying to flash some code in a pinch, there are some more expedient options out there. We’re particularly fond of using a development board to program the bare MCU.

Continue reading “Turning The Raspberry Pi Into A MCU Programmer” →

Comparing Shortwave Antennas With RTL-SDR And Python

September 5, 2020 by 7 Comments

Measuring the performance of antennas in absolute terms that can involve a lot of expensive equipment and specialized facilities. For practical applications, especially when building antennas, comparing performance in relative terms is more practical. Using cheap RTL-SDR dongles and Python, [Eric Urban] was able to compare the performance of two shortwave/HF antennas, and documented the entire process.

The two antennas in question was a single band inverted-L and smaller broadband T3FD antenna. [Eric] first gathered performance data for each over few days, connected to separate PCs with RTL-SDRs via low-pass filters. These were set up to receive FT8 transmissions, a popular digital ham radio mode, which allowed [Eric] to automate data collection completely. GQRX, a software receiver, converted the signals to audio, which was then piped into WSJT-X for demodulation.

Data for each received FT8 transmission was recorded to a log file. [Eric] also modified GQRX and WSJT-X to give him all the remote control features he needed to automatically change frequencies. Between the two antenna setups, more than 100,000 FT8 transmissions were logged. Using the recorded data and Python he compared the number of received transmissions, the distance, and the heading to the transmitters, using the location information included in many FT8 transmissions. Where the same transmission was received by both antennas, the signal-to-noise ratios was compared.

From all this data, [Eric] was able to learn that the inverted-L antenna performed better than the T3FD antenna on three of the four frequency bands that were tested. He also discovered that the inverted-L appeared to be “deaf” in one particular direction. Although the tests weren’t perfect, it is impressive how much practical data [Eric] was able to gather with low-cost hardware. Continue reading “Comparing Shortwave Antennas With RTL-SDR And Python” →