I2C Paper Tape Reader Is Not What You Think

We’re not quite sure what drove the development of this project, but [shapoco] has put together an intriguing device that reads I2C signals (Japanese Twitter link) which have been printed as black and white rectangles on paper tape. He wrote a program that prints an I2C byte stream onto strips containing the SCL and SDA signal patterns. Once printed, you cut the strips from the paper and glue them together into one long piece, making a complete message — in this case, commands to a small LCD screen that will display the phrase “Hello, Tape I2C”.

We’re not sure exactly sure what’s inside that rectangular widget epoxied to the bottom of that perf board through which the tape passes. But clearly, it must contain a pair of LEDs to illuminate the tape and a pair of sensors to detect the reflection off the tape (looking at the wiring, it seems unlikely that anything is mounted underneath the tape). According to one machine-translated Twitter message, detection is done using a Schmitt trigger made from an LM393 comparator with hysteresis (see this TI app note for a review of this type of circuit). Here’s a scope capture of the resulting signals. [Shapoco] notes that the circuit can operate much faster — the tape is being pulled slowly in the video to make it easier to see.

This is not [shapoco]’s first experiment in optical I2C communications. Check out the second video down below where he’s reading I2C signals from a computer’s display. One person tweeted about how software source code was sometimes printed optically in old Byte magazines many years ago, a topic we talked about in Hackaday Podcast #049 last year when discussing Cauzin strips.

Besides just being cool, and possibly helpful as an educational device, does this technique have any real-world applications these days? Let us know your thoughts in the comment section below. Thanks to [Manawyrm] for sending us this tip.

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Genetically Modified Mosquitos: Biohacking For Disease Prevention

Many years ago, I took a summer trip to the Maryland shore with some friends. One of my buddies and I got bored with playing football on the beach, so we decided to take a hike on one of the many trails back into the wooded area behind the dunes. At the trailhead we noticed a prominent sign, warning about the presence of “very aggressive mosquitos” and not to enter without first applying ample insect repellent. We scoffed at the warning as only young idiots could and soldiered on, bare-legged and confident that we’d be fine.

About three minutes into our hike, a small group came pelting down the trail in a panic. “It’s true! Turn back!” they shouted as they flew past us. Undeterred, or at least unwilling to appear that way to each other, we pressed on, only to discover a few minutes later that we were making a substantial blood sacrifice to the next generation of mosquitos on Assateague Island. We couldn’t bear more than a few seconds before turning tail and running back to the beach and jumping into the ocean to get rid of the last few dozen bloodsuckers.

I learned a valuable lesson from that experience, as well as developing a deep and abiding hatred of mosquitos. It turns out I’m in good company — pretty much everyone hates mosquitos, which are not just a nuisance but can be downright dangerous to be around. But if tests with genetically engineered mosquitos currently underway in Florida turn out well, we may be able to finally turn the tide against mosquito-borne diseases, simply by killing all the females before they ever reach adulthood.

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Commodore 64 Emulator In VR Delivers A Full 80s Experience

The simulated color CRT monitor looks surprisingly convincing in VR.

One way to play with vintage hardware without owning the hardware is to use an emulator, but [omni_shaNker] announced taking it to the next level by using VR to deliver a complete Commodore 64 system, in its full glory, complete with a native 80s habitat playset! This is a pretty interesting angle for simulating vintage hardware, especially since the emulator is paired with what looks like a pretty convincing CRT monitor effect in VR, not to mention a virtual 5.25″ floppy drive that makes compellingly authentic sounds.

The project is hosted on GitHub and supports a variety of VR hardware, but for owners of Oculus headsets, the application is also available on SideQuest for maximum convenience. SideQuest is essentially an off-the-books app store for managing software that is neither approved nor distributed by Facebook. Oculus is owned by Facebook, and Facebook is keen to keep a tight grip on their hardware.

As functional as the application is, there are still improvements and optimizations to be made. To address this, [omni_shaNker] put out a call for beta testers on Reddit, so if that’s up your alley be sure to get in touch. A video demonstration and overview that is chock-full of technical details is also embedded below; be sure to give it a watch to see what the project is all about.

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Keep Livestock From Razing Your Field With An Overgrazing Shield

You know, not every solution needs to be complicated to be absolutely awesome. Take the humble clothespin, for example, two pieces of cleverly carved wood (or plastic; we won’t judge) and a spring. And yet, the service it provides is useful for many applications.

The same simple elegance is also present in [Anteneh]’s overgrazing shield. When sheep and other animals are allowed to eat the vegetation down to the soil, it leads to soil erosion if not kept in check with regular grazing location rotation. As it turns out, if you want to keep an animal from eating grass and plants down to the soil, just slip a leather harness over its neck with a piece of wood in the right place so it literally can’t graze any lower than the wood allows.

According to [Anteneh]’s prototype tests, it only takes a few seconds to fit the shield to the animal’s head and neck, and then they’re off to grazing to the prescribed depth. We think this is a great solution and hope to see it in wide use along with regular rotation.

Need a way to track your livestock? [Sean Boyce]’s experiments with subcutaneous pig tracking makes for a good read, but the reality of that system will probably have you looking for a simpler solution.

Soundbar Bested By Virtual Android Bluetooth Sniffer

Out of the box, the Yamaha YAS-207 soundbar can be remotely controlled over Bluetooth, but only when using a dedicated application on iOS or Android. Users who want to command their hardware with their computer, or any other Bluetooth device for that matter, are left out in the cold. Or at least they were, before [Wejn] got on the case.

To capture the communication between the soundbar and the application, [Wejn] first installed Android-x86 in a virtual machine on his computer and then enabled the “Bluetooth HCI snoop log” within Developer Settings. From there, a netcat command running on the virtual Android device continually sent the contents of the btsnoop_hci.log file out to Wireshark on his Linux desktop. As he hit buttons in the Yamaha application, he could watch the data come in live. We’ve seen plenty of people use Android’s integrated Bluetooth packet capture in the past, but never quite like this. It’s certainly a tip worth mentally filing away for the future.

The Pi can now control the TOSLINK connected speakers.

From there, things move pretty quickly. [Wejn] is able to determine that the devices are communicating over a virtual serial port, and starts identifying individual command and response packets. It turns out the commands closely mirror the NEC IR codes that he’d previously decoded on a whim, which helped clear things up. Once the checksum was sorted out, writing some code that can talk to the soundbar from his Raspberry Pi media player was the next logical step.

[Wejn] combined this with the Shairport Sync project, which lets the Raspberry Pi turn on the speaker and switch the input over when he wants to stream AirPlay from his phone. But of course, the same technique could be applied to whatever source of digital audio captures your fancy.

This is one of those posts you should really read in its entirety to truly appreciate. While every device is going to be different, the basic principles and workflow that [Wejn] demonstrates in this project will absolutely be useful in your own reverse engineering adventures. If you’re more of a visual learner, we recently covered a series of YouTube tutorials that cover sniffing BLE devices that’s not to be missed as well.

Active Suspension On A DIY Racing Car

In automotive engineering, almost every design choice is a trade-off, like performance versus fuel economy, straight-line speed versus cornering, or strength versus weight. Inspired by controversial technology for the 2020 Formula 1 season, [Wesley Kagan] is fitting his DIY racing car with actuators to change the suspension geometry while driving.

The controversial technology in question is Mercedes’ DAS (Dual Axis Steering). By pushing the steering wheel in and out, the driver and change the wheel alignment to toe-out (wheels pointing outwards) for better cornering stability, or neutral for the straight sections.

Like many racing cars, [Wesley] used A-arm suspension on his racing car. By replacing the top arms with telescoping tubes with mounted actuators, the geometry can be actively adjusted. For this proof of concept, he used linear actuators but plans to move to a hydraulic system for improved speed and force. The length of the A-arms is sensed with ultrasonic sensors, while a potentiometer senses the suspension position.

Tuning the software for optimum performance will probably require some track testing which we hope to see in the future. This is not the first time [Wesley] has taken inspiration from a multimillion-dollar project and implemented it in his garage. Just check out how he converted a Miata and a Harbor Freight engine to a Free Valve system.

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Hackaday Links: May 2, 2021

Mars is getting to be a busy place, what with helicopters buzzing around and rovers roving all about the place. Now it’s set to get a bit more crowded, with the planned descent of the newly-named Chinese Zhurong rover. Named after the god of fire from ancient Chinese mythology, the rover, which looks a little like Opportunity and Spirit and rides to the surface aboard something looking a little like the Viking lander, will carry a suite of scientific instruments around Utopia Planitia after it lands sometime this month. Details are vague; China usually plays its cards close to the vest, and generally makes announcements only when a mission is a fait accompli. But it appears the lander will leave its parking orbit, which it entered back in February, sometime this month. It’s not an easy ride, and we wish Zhurong well.

Speaking of space, satellites don’t exactly grow on trees — until they do. A few groups, including a collaboration between UPM Plywood and Finnish startup Arctic Astronautics, have announced intentions to launch nanosatellites made primarily of wood. Japanese logging company Sumitomo Forestry and Kyoto University also announced their partnership, formed with the intention to prove that wooden satellites can work. While it doesn’t exactly spring to mind as a space-age material, wood does offer certain advantages, including relative transparency to a wide range of the RF spectrum. This could potentially lead to sleeker satellite designs, since antennae and sensors could be located inside the hull. Wood also poses less of a hazard than a metal spaceframe does when the spacecraft re-enters the atmosphere. But there’s one serious disadvantage that we can see: given the soaring prices for lumber, at least here in the United States, it may soon be cheaper to build satellites out of solid titanium than wood.

If the name Ian Davis doesn’t ring a bell with you, one look at his amazing mechanical prosthetic hand will remind you that we’ve been following his work for a while now. Ian suffered a traumatic amputation of the fingers of his left hand, leaving only his thumb and palm intact, and when his insurance wouldn’t pay for a prosthetic hand, he made his own. Ian has gone through several generations, each of which is completely mechanical and controlled only by wrist movements. The hands are truly works of mechanical genius, and Ian is now sharing what he’s learned to help out fellow hand-builders. Even if you’re not building a hand, the video is well worth watching; the intricacy of the whiffle-tree mechanism used to move the fingers is just a joy to behold, and the complexity of movement that Ian’s hand is capable of is just breathtaking.

If mechanical hands don’t spark your interest, then perhaps the engineering behind top fuel dragsters will get you going. We’ll admit that most motorsports bore us to tears, even with the benefit of in-car cameras. But there’s just something about drag cars that’s so exciting. The linked video is a great dive into the details of the sport, where engines that have to be rebuilt after just a few seconds use, fuel flows are so high that fuel lines the size of a firehouse are used, and the thrust from the engine’s exhaust actually contributes to the car’s speed. There’s plenty of slo-mo footage in the video, including great shots of what happens to the rear tires when the engine revs up. Click through the break for more!

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