Day: July 10, 2024

PCB Design Review: HAB Tracker With ATMega328P

July 10, 2024 by 15 Comments

Welcome to the Design Review Central! [VE3SVF] sends us their board, and it’s a HAB (High Altitude Balloon) tracker board. It’s got the venerable ATMega28P on it, a LoRa modem and a GPS module, and it can be powered from a LiIon battery. Stick this board with its battery onto a high-altitude balloon, have it wake up and transmit your coordinates every once in a while, and eventually you’ll find it in a field – if you’re lucky. Oherwise, it will get stuck hanging on a tree branch, and you will have to use a quadcopter to try and get it down, and then, in all likelihood, a second quadcopter so that you can free the first one. Or go get a long ladder.

The ATMega328P is tried and true, and while it’s been rising in price, it’s still available – with even an updated version that sports a few more peripherals; most importantly, you’re sure to find a 328P in your drawer, if not multiple. Apart from that, the board uses two modules from a Chinese manufacturer, G-Nice, for both GPS and Lora. Both of these modules are cheap, making this tracker all that more accessible; I could easily see this project being sold as a “build your own beacon” kit!

Let’s make it maybe a little nicer, maybe a little cheaper, and maybe decrease the power consumption a tad along the way. We’ll use some of the old tricks, a few new ones, and talk about project-specific aspects that might be easy to miss.

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A New Raspberry 5 DSI Cable Makes Using Screens Easier

July 10, 2024 by 8 Comments

Arguably the greatest strength of the Raspberry Pi is the ecosystem — it’s well-supported by its creators and the aftermarket. At the same time, the proliferation of different boards has made things more complicated over the years. Thankfully, though, the community is always standing by to help fix any problems. [Rastersoft] has stepped up in this regard, solving an issue with the Raspberry Pi 5 and DSI screen cables.

The root cause is that the DSI cable used on the Raspberry Pi 5 has changed relative to earlier boards. This means that if you use the Pi 5 with many existing screens and DSI cables, you’ll find your flat ribbon cable gets an ugly twist in it. This can be particularly problematic when using the cables in tight cases, where they may end up folded, crushed, or damaged.

[Rastersoft] got around this by designing a new cable that avoided the problem. It not only solves the twist issue, but frees up space around the CPU if you wish to use a cooler. Thanks to modern PCB houses embracing flexible boards, it’s easy to get it produced, too.

This is a great example of the democratization of PCB and electronics production in general. 20 years ago, you wouldn’t be able to make a flex cable like this without ordering 10,000 of them. Today, you can order a handful for your own personal use, and share the design with strangers on a whim. Easy, huh? It’s a beautiful world we live in.

Model Rocket Nails Vertical Landing After Three-Year Effort

July 10, 2024 by 30 Comments

Model rocketry has always taken cues from what’s happening in the world of full-scale rockets, with amateur rocketeers doing their best to incorporate the technologies and methods into their creations. That’s not always an easy proposition, though, as this three-year effort to nail a SpaceX-style vertical landing aptly shows.

First of all, hats off to high schooler [Aryan Kapoor] from JRD Propulsion for his tenacity with this project. He started in 2021 with none of the basic skills needed to pull off something like this, but it seems like he quickly learned the ropes. His development program was comprehensive, with static test vehicles, a low-altitude hopper, and extensive testing of the key technology: thrust-vector control. His rocket uses two solid-propellant motors stacked on top of each other, one for ascent and one for descent and landing. They both live in a 3D printed gimbal mount with two servos that give the stack plus and minus seven degrees of thrust vectoring in two dimensions, which is controlled by a custom flight computer with a barometric altimeter and an inertial measurement unit. The landing gear is also clever, using rubber bands to absorb landing forces and syringes as dampers.

The video below shows the first successful test flight and landing. Being a low-altitude flight, everything happens very quickly, which probably made programming a challenge. It looked like the landing engine wasn’t going to fire as the rocket came down significantly off-plumb, but when it finally did light up the rocket straightened and nailed the landing. [Aryan] explains the major bump after the first touchdown as caused by the ascent engine failing to eject; the landing gear and the flight controller handled the extra landing mass with aplomb.

All in all, very nice work from [Aryan], and we’re keen to see this one progress.

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