Hacking A Solar Inverter RF Interface

June 4, 2021 by Danie Conradie 4 Comments

One of the main advantages of cheap wireless modules is that they get used in consumer electronics, so if you know what’s being used you can build your own compatible hardware. While investigating the RF interface used in a series of cheap “smart” solar inverters [Aaron Christophel], created an Arduino library to receive inverter telemetry using a $2 RF module. See the demonstration after the break.

[Aaron] bought the inverter and ~40 euro USB “Data Box” that allows the user to wirelessly monitor the status of the inverter. Upon opening the two units, he found that they used LC12S 2.4Ghz modules, which create a wireless UART link. With a bit of reverse engineering, he was able to figure out the settings for the RF modules and the serial commands required to request the status of the inverter. He doesn’t delve into the possible security implications, but there doesn’t appear to be any form of encryption in the link. It should be possible for anyone with a module to sniff the messages, extract the ID of the inverter, and hijack the link. Just knowing the status of the inverter shouldn’t be all that dangerous, but he doesn’t mention what other commands can be sent to the module. Any others could have more severe implications.

Sniffing the wireless signal flashing through the air around us is a regular topic here on Hackaday. From testing the security of WiFi networks with an ESP32 to monitoring SpaceX launches with an SDR, the possibilities are infinite.

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Teaching A Machine To Be Worse At A Video Game Than You Are

May 31, 2021 by Dan Maloney 6 Comments

Is it really cheating if the aimbot you’ve built plays the game worse than you do?

We vote no, and while we take a dim view on cheating in general, there are still some interesting hacks in this AI-powered bot for Valorant. This is a first-person shooter, team-based game that has a lot of action and a Counter-Strike vibe. As [River] points out, most cheat-bots have direct access to the memory of the computer which is playing the game, which gives it an unfair advantage over human players, who have to visually process the game field and make their moves in meatspace. To make the Valorant-bot more of a challenge, he decided to feed video of the game from one computer to another over an HDMI-to-USB capture device.

The second machine has a YOLOv5 model which was trained against two hours of gameplay, enough to identify friend from foe — most of the time. Navigation around the map was done by analyzing the game’s on-screen minimap with OpenCV and doing some rudimentary path-finding. Actually controlling the player on the game machine was particularly hacky; rather than rely on an API to send keyboard sequences, [River] used a wireless mouse dongle on the game machine and a USB transmitter on the second machine.

The results are — iffy, to say the least. The system tends to get the player stuck in corners, and doesn’t recognize enemies that pop up at close range. The former is a function of the low-res minimap, while the latter has to do with the training data set — most human players engage enemies at distance, so there’s a dearth of “bad breath range” encounters to train to. Still, we’re impressed that it’s possible to train a machine to play a complex FPS game at all, let alone this well.

Reverse Engineering Self-Powered Wireless Switches

May 2, 2021 by Danie Conradie 30 Comments

The plethora of wireless communications technologies have cut the comms wire for many applications, but these devices still require power. For home automation, this might mean a battery or mains power, but there is also an alternative that we don’t see often: Kinetic power. [Bigclivecom] bought some kinetic switches from eBay and gave it his usual reverse engineering treatment.

True to the marketing, these switches do not require external power or a battery to send a wireless signal. Instead, it harvests energy from the magnetic latching action of the switch itself. When the switch is actuated, a small current is induced in a coil as the polarity of the magnetic field through its core changes rapidly. Through a series of diodes and resisters, the energy is stored in a capacitor, which is then used to power a small transmitter chip. The antenna coil is wrapped around the switch housing.

The receiver side is powered by mains and includes a relay output for lights. It would be really nice to have a hacker-friendly module for projects. We would be curious to see the range that these devices are capable of.

The same technology is used inside the Philips Hue Tap switch, of which Adafruit did a teardown a few years ago. If you want to learn more about RF modulation, check out the crash course article we put out a while back. Of course, the RTL SDR is an indispensable and affordable tool if you want to do some experimentation.

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Getting On The Air With A 10-Minute-ish Ham Transmitter

March 11, 2021 by Dan Maloney 30 Comments

Artificially constrained designs can be among the most challenging projects to build, and the most interesting to consider. The amateur radio world is no stranger to this, with homebrew radio designs that set some sort of line in the sand. Such designs usually end up being delightfully minimalist and deeply instructive of first principles, which is one reason we like them so much.

For a perfect example of this design philosophy, take a look at [VK3YE]’s twist on the classic “10-Minute Transmitter”. (Video, embedded below.)

The design dates back to at least the 1980s, when [G4RAW] laid down the challenge to whip up a working transmitter from junk bin parts and make a contact within 15 minutes — ten for the build and five for working the bands. [VK3YE] used the “oner” — one-transistor — design for his 10-minute transmitter, but invested some additional time into adding a low-pass filter to keep his signal clean, and a power amplifier to boost the output a bit.

Even with the elaborations, the design is very simple and easy to understand. Construction is the standard “ugly style” that hams favor for quick builds like this. There are no parts that would be terribly hard to find, and everything fits into a small metal box. The video below shows the design and build, along with some experiments with WebSDR receivers to check out range both with and without the power amplifier.

Seeing these kinds of builds really puts us in the mood for some low-power action. Could something like this pop up in “The $50 Ham” series? Quite possibly yes.

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Fixing NRF24L01+ Modules Without Going (Too) Insane

January 22, 2021 by Donald Papp 24 Comments

Good old nRF24L01+ wireless modules are inexpensive and effective. Well, they are as long as they work correctly, anyway. The devices themselves are mature and well-understood, but that doesn’t mean bad batches from suppliers can’t cause hair-pulling problems straight from the factory.

[nekromant] recently got a whole batch of units that simply refused to perform as they should, but not because they were counterfeits. The problem was that the antenna and PCB design had been “optimized” by the supplier to the point where the devices simply couldn’t work properly. Fortunately, [nekromant] leveraged an understanding of the problem into a way to fix them without going insane in the process. The test setup is shown in the image above, and the process is explained below. Continue reading “Fixing NRF24L01+ Modules Without Going (Too) Insane” →

Hackaday Links: November 8, 2020

November 8, 2020 by Dan Maloney 6 Comments

Saturday, November 7, 2020 – NOT PASADENA. Remoticon, the virtual version of the annual Hackaday Superconference forced upon us by 2020, the year that keeps on giving, is in full swing. As I write this, Kipp Bradford is giving one of the two keynote addresses, and last night was the Bring a Hack virtual session, which I was unable to attend but seems to have been very popular, at least from the response to it. In about an hour, I’m going to participate in the SMD Soldering Challenge on the Hackaday writing crew team, and later on, I’ll be emceeing a couple of workshops. And I’ll be doing all of it while sitting in my workshop/office here in North Idaho.

Would I rather be in Pasadena? Yeah, probably — last year, Supercon was a great experience, and it would have been fun to get together again and see everyone. But here we are, and I think we’ve all got to tip our hacker hats to the Remoticon organizers, for figuring out how to translate the in-person conference experience to the virtual space as well as they have.

The impact of going to a museum and standing in the presence of a piece of art or a historic artifact is hard to overstate. I once went to an exhibit of artifacts from Pompeii, and was absolutely floored to gaze upon a 2,000-year-old loaf of bread that was preserved by the volcanic eruption of 79 AD. But not everyone can get to see such treasures, which is why Scan the World was started. The project aims to collect 3D scans of all kinds of art and artifacts so that people can potentially print them for study. Their collection is huge and seems to concentrate on classic sculptures — Michelangelo’s David is there, as are the Venus de Milo, the Pieta, and Rodin’s Thinker. But there are examples from architecture, anatomy, and history. The collection seems worth browsing through and worth contributing to if you’re so inclined.

For all the turmoil COVID-19 has caused, it has opened up some interesting educational opportunities that probably wouldn’t ever have been available in the Before Time. One such opportunity is an undergraduate-level course in radio communications being offered on the SDRPlay YouTube channel. The content was created in partnership with the Sapienza University of Rome. It’s not entirely clear who this course is open to, but the course was originally designed for third-year undergrads, and the SDRPlay Educators Program is open to anyone in academia, so we’d imagine you’d need some kind of academic affiliation to qualify. The best bet might be to check out the intro video on the SDRPlay Educator channel and plan to attend the webinar scheduled for November 19 at 1300 UTC. You could also plan to drop into the Learning SDR and DSP Hack Chat on Wednesday at noon Pacific, too — that’s open to everyone, just like every Hack Chat is.

And finally, as if bald men didn’t suffer enough disrespect already, now artificial intelligence is having a go at them. At a recent soccer match in Scotland, an AI-powered automatic camera system consistently interpreted an official’s glabrous pate as the soccer ball. The system is supposed to keep the camera trained on the action by recognizing the ball as it’s being moved around the field. Sadly, the linesman in this game drew the attention of the system quite frequently, causing viewers to miss some of the real action. Not that what officials do during sporting events isn’t important, of course, but it’s generally not what viewers want to see. The company, an outfit called Pixellot, knows about the problem and is working on a solution. Here’s hoping the same problem doesn’t crop up on American football.

Modern Radio Receiver Architecture: From Regenerative To Direct Conversion

July 17, 2020 by Al Williams 5 Comments

Modern radio receivers have a distinct advantage over the common early designs which I covered in my previous article. Most of the receivers you will have worked with over the past couple decades are designs by Edwin Armstrong; regenerative, superregenerative, or most commonly superheterodyne. These are distinguished by a few fascinating key traits that bring both benefits and drawbacks.

Today let’s dive into Mr. Armstrong’s receivers. I’ll also talk about DC receivers which, despite the name, are not made to listen to batteries. These are receivers you are much more likely to encounter in modern equipment.

Regenerative and Superregenerative

The regenerative receiver is all about doing more with less. You still see some of these in simple applications like RF remote controls. The idea derives from how an oscillator works. In a simple way of thinking, an oscillator is an amplifier with enough positive feedback that any tiny signal at the right frequency will amplify and then, through feedback, continue to output over and over. If everything were perfect, then, an oscillator would have infinite gain at a given frequency.

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