ATTiny NFC Thermometer keychain with keys

Tiny NFC-Powered Keychain Thermometer

What if your keychain could tell you the temperature, all while staying battery-free? That’s the essence of this innovative keychain ‘NFC_temp’ by [bjorn]. This nifty gadget harnesses energy from an NFC field—like the one created by your smartphone—to power itself just long enough to take a precise temperature reading. Using components like an ATTiny1626 microcontroller, a TMP117 thermometer, and an RF430CL330H NFC IC, NFC_temp cleverly stores harvested power in a capacitor to function autonomously.

The most impressive part? This palm-sized device (18×40 mm) uses a self-designed 13.56 MHz antenna to draw energy from NFC readers. The temperature is then displayed on the reader, with an impressive accuracy of ±0.1 °C. Creator [bjorn] even shared challenges, like switching from an analog sensor due to voltage instability, which ultimately led to his choice of the TMP117. Android phones work best with the tag, while iOS devices require a bit more angling for reliable detection.

Projects like NFC_temp underscore the creativity within open source. It’s a brilliant nod to the future of passive, wireless, energy-efficient designs. Since many of us will all be spending a lot of time around the Christmas tree this month, why not fit it in a bauble?

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Hackaday Links: November 24, 2024

We received belated word this week of the passage of Ward Christensen, who died unexpectedly back in October at the age of 78. If the name doesn’t ring a bell, that’s understandable, because the man behind the first computer BBS wasn’t much for the spotlight. Along with Randy Suess and in response to the Blizzard of ’78, which kept their Chicago computer club from meeting in person, Christensen created an electronic version of a community corkboard. Suess worked on the hardware while Christensen provided the software, leveraging his XMODEM file-sharing protocol. They dubbed their creation a “bulletin board system” and when the idea caught on, they happily shared their work so that other enthusiasts could build their own systems.

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Close-up of a woman's neck with a haptic patch

Hacking Haptics: The 19-Sensor Patch Bringing Touch To Life

On November 6th, Northwestern University introduced a groundbreaking leap in haptic technology, and it’s worth every bit of attention now, even two weeks later. Full details are in their original article. This innovation brings tactile feedback into the future with a hexagonal matrix of 19 mini actuators embedded in a flexible silicone mesh. It’s the stuff of dreams for hackers and tinkerers looking for the next big thing in wearables.

What makes this patch truly cutting-edge? First, it offers multi-dimensional feedback: pressure, vibration, and twisting sensations—imagine a wearable that can nudge or twist your skin instead of just buzzing. Unlike the simple, one-note “buzzers” of old devices, this setup adds depth and realism to interactions. For those in the VR community or anyone keen on building sensory experiences, this is a game changer.

But the real kicker is its energy management. The patch incorporates a ‘bistable’ mechanism, meaning it stays in two stable positions without continuous power, saving energy by recycling elastic energy stored in the skin. Think of it like a rubber band that snaps back and releases stored energy during operation. The result? Longer battery life and efficient power usage—perfect for tinkering with extended use cases.

And it’s not all fun and games (though VR fans should rejoice). This patch turns sensory substitution into practical tech for the visually impaired, using LiDAR data and Bluetooth to transmit surroundings into tactile feedback. It’s like a white cane but integrated with data-rich, spatial awareness feedback—a boost for accessibility.

Fancy more stories like this? Earlier this year, we wrote about these lightweight haptic gloves—for those who notice, featuring a similar hexagonal array of 19 sensors—a pattern for success? You can read the original article on TechXplore here.

A side view of an Asian woman with brown hair. She has a faint smile and is wearing an earring that looks somewhat like a large copper snowflake. Near the ear hole is a small PCB with a blinking LED. To the right of the image is the text "LED Earring, Recieved power 50 µW"

Power-Over-Skin Makes Powering Wearables Easier

The ever-shrinking size of electronics and sensors has allowed wearables to help us quantify more and more about ourselves in smaller and smaller packages, but one major constraint is the size of the battery you can fit inside. What if you could remotely power a wearable device instead?

Researchers at Carnegie Mellon University were able to develop a power transmitter that lets power flow over human skin to remote devices over distances as far a head-to-toe. The human body can efficiently transmit 40 MHz RF energy along the skin and keeps this energy confined around the body and through clothing, as the effect is capacitive.

The researchers were able to develop several proof-of-concept devices including “a Bluetooth
ring with a joystick, a stick-and-forget medical patch which logs data, and a sun-exposure patch with a screen — demonstrating user input, displays, sensing, and wireless communication.” As the researchers state in the paper, this could open up some really interesting new wearable applications that weren’t possible previously because of power constraints.

If you’re ready to dive into the world of wearables, how about this hackable smart ring or a wearable that rides rails?

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Hackaday Links: September 15, 2024

A quick look around at any coffee shop, city sidewalk, or sadly, even at a traffic light will tell you that people are on their phones a lot. But exactly how much is that? For Americans in 2023, it was a mind-boggling 100 trillion megabytes, according to the wireless industry lobbying association CTIA. The group doesn’t discuss their methodology in the press release, so it’s a little hard to make judgments on that number’s veracity, or the other numbers they bandy about, such as the 80% increase in data usage since 2021, or the fact that 40% of data is now going over 5G connections. Some of the numbers are more than a little questionable, too, such as the claim that 330 million Americans (out of a current estimate of 345.8 million people) are covered by one or more 5G networks. Even if you figure that most 5G installations are in densely populated urban areas, 95% coverage seems implausible given that in 2020, 57.5 million people lived in rural areas of the USA. Regardless of the details, it remains that our networks are positively humming with data, and keeping things running is no mean feat.

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Hack On Self: Sense Of Time

Every now and then, a commercial product aims to help you in your life journey, in a novel way, making your life better through its presence. Over the years, I’ve been disappointed by such products far more often than I have been reassured, seeing each one of them rendered unimaginative and purposeless sometimes even despite the creator’s best intentions. The pressures of a commercial market will choke you out without remorse, metal fingers firmly placed on your neck, tightening with every move that doesn’t promise profit, and letting money cloud your project’s vision. I believe that real answers can only come from within hacker communities, and as we explore, you might come to see it the same way.

This is the tip of the iceberg of a decade-long project that I hope to demonstrate in a year or two. I’d like to start talking about that project now, since it’s pretty extensive; the overall goal is about using computers to help with human condition, on a personal level. There’s a lot of talk about computers integrating into our lives – even more if you dare consult old sci-fi, much of my inspiration.

Tackling a gigantic problem often means cutting it down into smaller chunks, though, so here’s a small sub-problem I’ve been working on, for years now, on and off: Can you use computers to modify your sense of time?

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Programming Tiny Blinkenlight Projects With Light

[mitxela] has a tiny problem, literally: some of his projects are so small as to defy easy programming. While most of us would probably solve the problem of having no physical space on a board to mount a connector with WiFi or Bluetooth, he took a different path and gave this clever light-based programming interface a go.

Part of the impetus for this approach comes from some of the LED-centric projects [mitxela] has tackled lately, particularly wearables such as his LED matrix earrings or these blinky industrial piercings. Since LEDs can serve as light sensors, albeit imperfect ones, he explored exactly how to make the scheme work.

For initial experiments he wisely chose his larger but still diminutive LED matrix badge, which sports a CH32V003 microcontroller, an 8×8 array of SMD LEDs, and not much else. The video below is a brief summary of the effort, while the link above provides a much more detailed account of the proceedings, which involved a couple of false starts and a lot of prototyping that eventually led to dividing the matrix in two and ganging all the LEDs in each half into separate sensors. This allows [mitxela] to connect each side of the array to the two inputs of an op-amp built into the CH32V003, making a differential sensor that’s less prone to interference from room light. A smartphone app alternately flashes two rectangles on and off with the matrix lying directly on the screen to send data to the badge — at a low bitrate, to be sure, but it’s more than enough to program the badge in a reasonable amount of time.

We find this to be an extremely clever way to leverage what’s already available and make a project even better than it was. Here’s hoping it spurs new and even smaller LED projects in the future.

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