Wristband RFID unlocks car door and starts engine

[João Ribeiro] is an electronics engineer by day, but in his free time he likes to ply his trade on everyday items. Recently he’s been integrating his own microcontroller network to unlock and start his car via RFID. In addition to the joy of pulling apart the car’s interior, he spent time designing his own uC breakout board and developing an RFID reader from a single chip.

He’s working with a 1988 Mercedes that has very little in the way of electronics. It sounds like the stock vehicle didn’t even include a CAN bus so the prelude to the RFID hack had him installing a CAN bus network made up of two microcontrollers. One reads the velocity and RPM while the other displays it on the tachometer. When he began the tag-based entry system he used an RFID reader module for prototyping, but eventually built his own reader around the TRF7960 chip. This included etching his own receiver coil which was mounted in the side-view mirror bracket. To unlock the doors he holds the bracelet up to the mirror and the vehicle lets him in. The video after the break starts with a demonstration of the completed project and moves on to some build videos.

We certainly like the idea of using a bracelet rather than implanting the tag in the meaty part of your hand.

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Configurable RFID tag from 7400 logic chips

This soldering nightmare is a configurable RFID tag which has been built from 7400-series logic chips. The beast of a project results in an iPhone-sized module which can be used as your new access card for security systems that uses the 125 kHz tags. The best part is that a series of switches makes the tag hand programmable, albeit in binary.

Of course this is an entry in this year’s 7400 Logic Competition. It’s from last year’s winner, and he’s spent a lot of time documenting the project; which we love. We were surprised that this many chips can be powered simply by what is induced in the coil from the reader. This is just one of the reasons the 7400-series have been so popular over the years. After working out the numbers, a 64-bit shift register was built to feed the tag ID to the encoding portion of the design. There were many kinks to work out along the way, but once it was functional a surface-mount design was put together resulting in the final product shown off in the video after the break.

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Transit pass controls this home security system

[Folkert van Heusden] installed a bunch of cameras in and around his home. Ostensibly this is for watching the kitties from work, but we’re sure the more accepted purpose is for security. He and his wife don’t really want the cameras rolling when they’re at home. So he added a system by the front door with uses a transit pass to turn on and off the security cameras.

The pass is an RFID tag which gets them on the subways, trains, and buses around the Netherlands. To use it with this system he needed an RFID reader. The one he chose is a USB device which enumerates as an HID keyboard. When it detects a valid card it outputs the tag id as a string of characters. [Folkert's] setup uses an eeePC with a broken keyboard to connect to the reader. A perl script monitors the feed from the reader, and verifies each code as it is received. After authentication the script will enable or disable the networked cameras and update the LED readout accordingly. To keep everything hidden he put it in the closet, using a hole (from a doorknob?) as a wire pass-through.

Scratch-built RFID reader

We never bought an RFID reader because it seems too simple to be all that much fun. But [Abdullah] really caught our eye with his latest project. It’s an RFID reader built from discrete parts, and that’s an adventure we can get behind!

His write-up dives right into the theory of the device. He wrapped his own coil, which measure about one microhenry, then shares an equation used to calculate the appropriate capacitor pair for it. This is fed by a 125 kHz oscillator and works as the most basic reader. In practice this needs more components for rock-solid operation and he quickly moves to a marginally more complicated circuit which still does exactly the same thing.

He is now able to detect RFID tag data by reading this circuit with an oscilloscope. But the signal is very very weak. The rest of the post focuses on how to best utilize an OpAmp to increase signal quality and on/off time.

If you’re looking to recreate his reader [Abdullah] included a Kicad schematic and board layout.

No secret knocks required at [Steve's] house – your subway pass will do


[Steve] is often host to all sorts of guests, and he was looking for an easy way to let his friends come and go as they please. After discovering that his front door came equipped with an electronic strike, he decided that an RFID reader would be a great means of controlling who was let in, and when.

Giving all your friends RFID cards and actually expecting that they carry them is a bit of a stretch, but lucky for [Steve] he lives near Boston, so the MBTA has him covered. Just about everyone in town has an RFID subway pass, which pretty much guarantees that [Steve’s] cohorts will be carrying one when they swing by.

He crafted a stylish set of wooden boxes to contain both the RFID reader and the Arduino that controls the system, matching them to the Victorian styling of his home. A single button can control the setup, allowing him to add and remove cards from access lists without much fuss. For more granular control however, [Steve] can always tweak settings from the Arduino serial console.

The card system is both stylish and useful – a combination that’s hard to beat.

Learn a new language with the Babel Fish

The Babel fish from Hitchhiker’s Guide to the Galaxy is one of the strangest things in the universe. After inserting a Babel fish into your ear, it feeds off brain wave energy and excretes a matrix from the conscious frequencies into the speech areas of the brain. It’s invaluable as a universal translator, but until Earth is targeted for demolition we’ll have to make do with [Becky] from Adafruit’s Babel fish language toy.

[Becky]‘s Babel fish is still able to feed off the energy given off by language, but in this case the energy comes from a set of RFID cards on which Chinese characters are written. After waving these RFID flash cards in front of the Babel fish, a wave shield connected to the Arduino plays a recording of how the logogram on the flash card should sound when pronounced.

While it’s not a biologically engineered fish that simultaneously proves and disproves the existence of god, every human endeavor – learning a language included – needs more [Douglas Adams] references. You can check out [Becky]‘s Babel fish demo video after the break.

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Store your RFID transit card inside your cellphone

Check it out, this is a Boston transit pass — or at least the parts of it that matters. [Becky Stern] got rid of the rest in a bid to embed the RFID tag inside her cellphone.

The transit pass, called a CharlieCard, started out as a normal credit card shaped tag which you might use for access in the workplace. She unsheathed the chip and its antennae by giving it a generous soak in acetone. In about thirty minutes the plastic card looks more like paper pulp, and you can gently fish out the electronics. These are now small enough to fit in the back cover of a cellphone much like those inductive charging hacks.

[Becky] put hers in an iPhone. But the idea comes from [Dhani Sutanto] who used the same technique to extract the coil from a London transit pass. He then embedded the hardware in a resin cast ring.

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