rfid

188 Articles

Cat Feeder Depends On RFID To Keep The Peace At Dinnertime

February 28, 2023 by 10 Comments

Anyone with more than one cat can tell you that the joy mischief they bring into your life is much more than twice that of a single cat. And if those felines have different dietary needs, you can end up where [Benjamin Krejci] found himself, which resulted in this fancy RFID cat feeder.

For a little backstory, [Ben]’s furry friends [Luna] and [Fermi] have vastly different eating styles, with the former being a grazer and the latter more of a “disordered eater,” to put it politely. [Fermi] tends to eat until she vomits, which is fun, and muscles her pickier sister away from the bowl if there’s anything left in it. [Ben]’s idea was to leverage [Luna]’s existing RFID chip, which he figured would be a breeze. But the vet-inserted chip is designed to be read by a high-power reader directly in contact with the cat’s skin, which made reliably reading the chip a challenge.

Several round of design iteration resulted in the current configuration, with a large antenna coil poised above and behind the food dispenser. [Luna] has no choice but to put the back of her neck and shoulder blades almost directly in contact with the coil, which makes it easier to read the 134.2-kHz chip with a long-distance RFID module. If [Luna]’s chip is found, the lid on the food bowl opens gently and quietly, so as not to spook the mild-mannered cat. The lid stays open as long as [Luna] is in place thanks to some IR sensors, but as soon as she backs out, the lid comes down to keep [Fermi] from gorging herself.

Hats off to [Ben] for working through the problem and coming up with what looks like a fine solution. We suppose he could have tried something easier like weighing the two cats to distinguish between them, but this seems like a cleaner solution to us.

A radio with a white front grate and wood edges sits on a grey surface. Next to the radio are small white disks with colorful edges reminicient of microdisc-sized records. A yellow-ringed disk sits on the radio. The handwritten title says, "Summer of 2011; Holidays in Barcelona"

Spotify Player Brings Back Physical Media

December 24, 2022 by 21 Comments

Digital music has made keeping all your tunes with you a lot more convenient, but have we lost something with dematerialization? [Jordi Parra] felt that there was something lacking with the digital music experience and designed a Spotify player with a tactile interface.

Specific playlists are selected via small RFID tags that look like a cross between a MiniDisc and a vinyl record. As this is a prototype, an Arduino reads the RFID tag, but needs a computer to actually play the Spotify playlist. Future iterations could include an integrated speaker and run libspotify to create a self-contained device.

While there is still work to do for a fully seamless experience, we love the details in the industrial design of this project. Clean simple lines and a combination of wood and more modern materials make this feel like a timeless piece of tech. Definitely check out the full photo gallery including shots of the really impressive packaging.

Want more digital music with a tactile interface? Check out this MP3 Player Shelf or a Simple Internet Radio Transplant.

Kids’ Jukebox Based On Arduino With RFID

December 16, 2022 by 10 Comments

Consumer electronics aimed at young children tend to be quite janky and cheap-looking, and they often have to be to survive the extreme stress-testing normal use in this situation. You could buy a higher quality item intended for normal use, but this carries the risk of burning a hole in the pockets of the parents. To thread the needle on this dilemma for a child’s audiobook player, [Turi] built the Grimmboy for a relative of his.

Taking its name from the Brothers Grimm, the player is able of playing a number of children’s stories and fables in multiple languages, with each physically represented by a small cassette tape likeness with an RFID tag hidden in each one. A tape can be selected and placed in the player, and the Arduino at the center of it will recognize the tag and play the corresponding MP3 file stored locally on an SD card. There are simple controls and all the circuitry to support its lithium battery as well. All of the source code that [Turi] used to build this is available on the project’s GitHub page.

This was also featured at the Arudino blog as well, and we actually featured a similar project a while ago with a slightly different spin. Both are based on ideas from Tonuino, an open source project aimed at turning Arduinos into MP3 players. If you’re looking to build something with a few more features, though, take a look at this custom build based on the RP2040 microcontroller instead.

Scramblepad Teardown Reveals Complicated, Expensive Innards

November 18, 2022 by 28 Comments

What’s a Scramblepad? It’s a type of number pad in which the numbers aren’t in fixed locations, and can only be seen from a narrow viewing angle. Every time the pad is activated, the buttons have different numbers. That way, a constant numerical code isn’t telegraphed by either button wear, or finger positions when punching it in. [Glen Akins] got his hands on one last year and figured out how to interface to it, and shared loads of nice photos and details about just how complicated this device was on the inside.

Just one of the many layers inside the Scramblepad.

Patented in 1982 and used for access control, a Scramblepad aimed to avoid the risk of someone inferring a code by watching a user punch it in, while also preventing information leakage via wear and tear on the keys themselves. They were designed to solve some specific issues, but as [Glen] points out, there are many good reasons they aren’t used today. Not only is their accessibility poor (they only worked at a certain height and viewing angle, and aren’t accessible to sight-impaired folks) but on top of that they are complex, expensive, and not vandal-proof.

[Glen]’s Scramblepad might be obsolete, but with its black build, sharp lines, and red LED 7-segment displays it has an undeniable style. It also includes an RFID reader, allowing it to act as a kind of two-factor access control.

On the inside, the reader is a hefty piece of hardware with multiple layers of PCBs and antennas. Despite all the electronics crammed into the Scramblepad, all by itself it doesn’t do much. A central controller is what actually controls door access, and the pad communicates to this board via an unencrypted, proprietary protocol. [Glen] went through the work of decoding this, and designed a simplified board that he plans to use for his own door access controller.

In the meantime, it’s a great peek inside a neat piece of hardware. You can see [Glen]’s Scramblepad in action in the short video embedded below.

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RFID Sticker On Bike Helmet Grants Garage Access

November 13, 2022 by 11 Comments

[Glen] might describe his project of opening his garage door by way of an RFID sticker on his bike helmet as simple, but some of the interfacing he needed to do was quite complex. He walks through the project from beginning to end, and there’s plenty to learn from.

When designing an RFID access control system, one has to decide what kind of reader and what kind of tags one wishes to use. They all function more or less the same way, but there are a lot of practical considerations to take into account such as cost, range, ease of use, and security options. After a lot of research, [Glen] decided on inexpensive sticker-style tags and a compatible reader supporting credentials with an ISO14443 UID that could be suitably mounted on a building’s exterior.

The actual opening of the door was the simple part, done by interfacing to a spare remote.

Breakout boards with ready-to-use code libraries exist for some RFID readers, but that wasn’t the case for the reader [Glen] had. He ended up rolling his own code to handle communication with the reader, with a Microchip PIC18F45K50 doing all the work of reading tags and performing access control. His code is on the project’s GitHub repository, and if you also find yourself needing to interface to a reader that uses the Wiegand protocol, you might want to give it a look.

Controlling the actual garage door was the easy part. All that took was soldering two wires across the switch contacts of a spare garage door opener remote, and using a relay to close the contacts. Simple and effective. You can see it in action in the short video, embedded below the break.

Overhead door access control might be a simple concept, but it comes in all shapes and sizes when enterprising hackers start looking for solutions. We’ve seen garage doors given the DIY IoT treatment, and even seen access controlled by a car’s headlamp flashes, which actually turned out to be more secure than it sounds.

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Front Door Keys Hidden In Plain Sight

October 18, 2022 by 27 Comments

If there’s one thing about managing a bunch of keys, whether they’re for RSA, SSH, or a car, it’s that large amounts of them can be a hassle. In fact, anything that makes life even a little bit simpler is a concept we often see projects built on to of, and keys are no different. This project, for example, eliminates the need to consciously carry a house key around by hiding it in a piece of jewelry.

This project sprang from [Maxime]’s previous project, which allowed the front door to be unlocked with a smartphone or tablet. This isn’t much better than carrying a key, since the valuable piece of electronics must be toted along in place of one. Instead, this build eschews the smartphone for a ring which can be worn and used to unlock the door with the wave of a hand. The ring contains an RFID which is read by an antenna that’s monitored by a Wemos D1 Mini. When it sees the ring, a set of servos unlocks the door.

The entire device is mounted on the front of the door about where a peephole would normally be, with the mechanical actuators on the inside. It seems just as secure (if not more so) than carrying around a metal key, and we also appreciate the aesthetic of circuit boards shown off in this way, rather than hidden inside an enclosure. It’s an interesting build that reminds us of some other unique ways of unlocking a door.

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Your Building’s RFID Access Tags Might Be Really Insecure

June 17, 2022 by 20 Comments

[Gabe Schuyler] had a frustrating problem when it came to getting into his building’s garage. The RFID access system meant he had to remove his gloves while sitting on his motorcycle to fish out the keytag for entry. He decided to whip up a better solution with less fuss.

His initial plan was to duplicate the keytag and to sew one into his gloves. Purchasing a 125 KHz RFID tag duplicator off eBay, he was able to quickly copy the tag, and create one that worked with his garage’s entry system. While the duplicate tags worked well, they were still too big to easily fit into a glove. Attempts to create a duplicate with a smaller tag failed, too. Eventually, [Gabe] turned up a ring complete with a compatible RFID chip, and was able to duplicate his entry tag onto that. Now, by wearing the ring, he can enter his garage and building with a simple wave of the hand, gloves on or off.

Of course, duplicating an RFID tag is no major hack. As per [Gabe]’s Shmoocon talk on the topic, however, it shows that many buildings are using completely insecure RFID access methods with little to no security whatsoever. Anyone that found an access tag lying on the ground could easily replicate as many as they wanted and enter the building unimpeded. It also bears noting that you can snoop RFID cards from further away than you might expect.