Learning By Playing

August 6, 2022 by Elliot Williams 5 Comments

Summer break has started over here, and my son went off to his first of a few day-camp-like activities last week. It was actually really cool – a workshop held by our local Fablab where they have the kids make a Minecraft building and then get to 3D-print it out. He loves playing and building in Minecraft, so we figured this would be right up his alley.

TinkerCAD model of a Lego Minecraft fox. Kiddo trifecta!

I had naively thought that it would work something like this: the kids build something in Minecraft, and then some software extracts the build and converts it into an STL file. Makes sense, because they already are more-or-less fluent in Minecraft modelling. And as I thought about that, it was a pretty clever idea.

But the truth was even sneakier. They warmed up by making something in Minecraft, then they opened up TinkerCAD, which was new to all of the kids, and built a 3D model there. Then they converted the TinkerCAD models into Minecraft, and played with what they had just built while the 3D printers hummed away.

The kids didn’t even flinch at having to learn a new 3D modelling tool, and the parallels to what they were already comfortable doing in Minecraft were obvious to them. My son came home and told me how much easier it was to do your 3D modelling in “this other Minecraft” – he meant TinkerCAD – because you don’t need to build everything out of single blocks. He thought he was playing games, but he’d secretly used his first CAD tool. Nice trick!

Then I look back and realize how much I must have learned about computers through playing as a kid. Heck, how much I still learn through playing. And of course I’m not alone – that’s one of the things that shines through in a large number of the projects we feature. Hack on and have fun!

Solar Plane Might Be Able To Last Through The Night

August 6, 2022 by Danie Conradie 15 Comments

“Just add solar panels to the wings” is a popular suggestion for improving the flight times of fixed-wing drones. However, the reality is not so simple, and it’s easy to hurt rather than help flight times with the added weight and complexity. The team at [Bearospace Industries] has been working on the challenge for the while, and their Solar Dragon aircraft recently had a very successful test flight, producing about 50% more power than it was consuming.

Instead of just trying to slap solar panels to an existing plane, an airframe should ideally be designed from the ground up as a balancing act between a range of factors. These include weight, efficiency, flight envelope, structural integrity, and maximum surface area for solar panels. All the considerations are discussed by [Bearospace] in an excellent in-depth video, which is an indispensable resource for anyone planning to build a solar plane.

[Bearospace] put all the theory into practice on Solar Dragon, which incorporates over 250 W of high-efficiency Maxeon C60 solar cells on the wing, tail, and triangular fuselage. The cells were wired to match their maximum power point voltage as closely as possible to the plane’s 3S lithium-ion battery pack, enabling the solar cells to charge the battery directly. To prevent overcharging, a solid state relay was used to disconnect the solar cells from the battery as required.

The batteries maintained the same average state of charge during the entire one-hour late morning flight, even though the panels were only connected 65% of the time. The team expects they might be able to get even better performance from the cells with a good MPPT charger, which will be required for less than ideal solar conditions.

Solar Dragon has a much larger payload capacity than was used during the test flight, more than enough for an MPPT charger and a significantly larger battery. With this and a long list of other planned improvements, it might be possible for the Solar Dragon to charge up during the day and fly throughout the night on battery power alone. One interesting potential approach mentioned is to also store energy in the form of altitude during the day, and use the aircraft’s slow sink rate to minimize battery usage at night.

Solar planes come up every few months on Hackaday, with [rctestflight] being one of the usual suspects. You also don’t need solar panels for long flight times, as [Matthew Heiskell] proved with a 10-hour 45 minute flight on battery power alone.

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Here’s How The Precursor Protects Your Privacy

August 6, 2022 by Arya Voronova 14 Comments

At some point, you will find yourself asking – is my device actually running the code I expect it to? [bunnie] aka [Andrew Huang] is passionate about making devices you can fundamentally, deeply trust, and his latest passion project is the Precursor communicator.

At the heart of it is an FPGA, and Precursor’s CPU is created out of the gates of that FPGA. This and a myriad of other design decisions make the Precursor fundamentally hard to backdoor, and you don’t have to take [bunnie]’s word for it — he’s made an entire video going through the architecture, boot protections and guarantees of the Precursor, teaching us what goes into a secure device that’s also practical to use.

If you can’t understand how your device works, your trust in it might be misplaced. In the hour long video, [bunnie] explains the entire stack, from the lower levels of hardware to root keys used to sign and verify the integrity of your OS, along the way demonstrating how you can verify that things haven’t gone wrong.

He makes sure to point out aspects you’d want to be cautious of, from physical security limitations to toolchain nuances. If you’re not up for a video, you can always check out the Precursor wiki, which has a treasure trove of information on the device’s security model.

As you might’ve already learned, it’s not enough for hardware to be open-source in order to be trustworthy. While open-source silicon designs are undoubtedly the future, their security guarantees only go so far.

Whether it’s esoteric hard drive firmware backdoors, weekend projects turning your WiFi card into a keylogger, or rootkits you can get on store-bought Lenovo laptops, hell, even our latest This Week In Security installment has two fun malware examples – there’s never a shortage of parties interested in collecting as much data as possible.

Everything You Wanted To Know About SDRAM Timing But Were Afraid To Ask

August 5, 2022 by Al Williams 9 Comments

One of the problems with being engaged in our hobby or profession is that people assume if you can build a computer out of chips, you must know all the details of their latest laptop computer. Most of the memory we deal with is pretty simple compared to DDR4 memory and if you’ve ever tried tweaking your memory, you know a good BIOS has dozens of settings for memory. [Actually Hardcore Overclocking] has a great description of a typical DDR4 datasheet and you can watch it in the video below.

Of course, he points out that knowing all this really doesn’t help you much with memory overclocking because you can’t really predict the complex effects without trial and error. However, most of us like to understand the knobs we are randomly twisting. On top of that, one theme of the video is that DRAM is dumb and simple. If you’ve ever thought about using it in a project, this might be a good place to start.

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E-paper Price Tags Combined To Create A Large Wireless Display

August 5, 2022 by Danie Conradie 3 Comments

E-paper price tags have become popular for retail stores over the past few years, which is great for hackers since we now have some more cheap commodity hardware to play with. [Aaron Christophel] went all on creating grid displays with E-paper price tags, up to a 20×15 grid.

E-paper price tags are great for these kinds of projects, since they are wireless, lightweight, and can last a long time with the onboard batteries. To mount the individual tags on the plywood backboard,[Aaron] simply glued Velcro to the backboard of the tags. The displays’ firmware is based on the reverse engineering work of [Dmitry Grinberg], flashed to a few hundred tags using a convenient 3D printed pogo pin programming jig. All the displays are controlled via a Zigbee USB dongle plugged into a PC running station software.

[Aaron] is also experimenting with the displays removed from their enclosure and popped into a 3D printed grid frame. The disadvantage is the loss of the battery holders and the antenna, which are both integrated into the enclosure. He plans to get around this by powering the displays from a single large battery, and connecting an ESP32 to the displays via ISP or UART.

This project comes hot on the heels of another E-ink grid display project that uses Bluetooth and a rather clever update scheme.

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Lawnmower Doesn’t Need A Base Station

August 5, 2022 by Al Williams 21 Comments

A recent tour of an old WWII-era aircraft carrier reminded us how hard navigation was before the advent of GPS. It used to be the work of skilled people to sight the sun or the stars and use giant books to figure out a vessel’s position. Now you just ask your phone to listen to some GPS satellites and you have precision undreamed of with other systems. But GPS sometimes isn’t enough. Just using conventional GPS, you can locate yourself to a couple of meters. The new L5 band, which isn’t on all satellites yet, can get you to about 30cm. But if you need better — up to around 1 or 2 cm — you need to use special techniques lumped together as GNSS enhancements. [Viktor] wanted to have an Arudino -based lawnmower, but wanted to use more conventional GPS techniques along with ultrawideband (UWB) ranging tags.

Given that the ranging anchors are in the mowing area, we aren’t sure why the mower even has GPS other than to geofence so you can’t start autonomous operations until you are in range of the tags. The three anchors are placed in a triangle, so if the robot knows the distance to each tag it can use some math to locate itself inside the area quite precisely.

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BPS.Space Succesfully Lands A Model Rocket

August 5, 2022 by Danie Conradie 16 Comments

If you’ve been following [Joe Barnard]’s rocketry projects for the past few years, you’ll know that one of his primary goals has been to propulsively land a model rocket like SpaceX. Now, 7 years into the rollercoaster journey, he has finally achieved that goal with the latest version of his Scout rocket.

Rocket touching down — We have touchdown!

Many things need to come together to launch AND land a rocket on standard hobby-grade solid fuel rocket motors. A core component is stabilization of the rocket during the entire flight, which achieved using a thrust-vectoring control (TVC) mount for the rocket motors and a custom flight computer loaded with carefully tuned guidance software. Until recently, the TVC mounts were 3D printed, but [Joe] upgraded it to machined aluminum to eliminate as much flex and play as possible.

Since solid-fuel rockets can’t technically be throttled, [Joe] originally tried to time the ignition time of the descent motor in such a manner that it would burn out as the rocket touches down. The ignition time and exact thrust numbers simply weren’t repeatable enough, so in his 2020 landing attempts, he achieved some throttling effect by oscillating the TVC side to side, reducing the vertical thrust component. This eventually gave way to the final solution, a pair of ceramic pincers which block the thrust of the motors as required.

Another interesting component is the landing legs. Made from light carbon fiber rods, they are released by melting a rubber band with nichrome wire and fold into place under spring tension. They also had to be carefully refined to absorb as much impact as possible without bouncing, which killed a few previous landing attempts.

Scrolling back through [Joe]’s videos and seeing the progress in his engineering is absolutely inspiring, and we look forward to his future plans. These include a functional scale model of the belly-flopping starship, a mysterious “meat rocket”, and the big one, a space shot to exceed 100 km altitude.

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