Using A Standard Coil For NFC Tag Implant Reading

October 8, 2014 by Mathieu Stephan 18 Comments

A few months ago Hackaday covered the xNT crowdfunding campaign which aimed at making an NTAG216 based NFC implant for different purposes. I actually backed it, found that standard NFC readers don’t perform well and therefore decided to try using a standard coil as an antenna for better reading performances.

Most NFC readers typically only have a small sweet spot where implant reading is possible. This is due to what we call coupling factor which depends on the reading distance and reader & NFC tag antenna geometries. Having a smaller antenna diameter increases the coupling factor and makes implant positioning easier.

In my detailed write-up you’ll find a good introduction to impedance matching, a process where a few passive components are added in series/parallel with an antenna to bring its complex impedance close to a RF signal transmitter’s. This usually requires expensive tools but allows optimal power transmission at a given frequency.

You may find our xNT coverage here.

Ask Hackaday: Can Paper USB Business Cards Exist?

August 25, 2014 by Mathieu Stephan 72 Comments

The swivelCard Kickstarter campaign recently received a lot of press coverage and makes some impressive claims as their goal is the development of USB and NFC business cards at a $3 unit price. While most USB-enabled business cards we featured on Hackaday were made of standard FR4, this particular card is made of paper as the project description states the team patented

a system for turning regular paper into a USB drive.

As you can guess this piqued our interest, as all paper based technologies we had seen until now mostly consisted of either printed PCBs or paper batteries. ‘Printing a USB drive on regular paper’ (as the video says) would therefore involve printing functional USB and NFC controllers.

Luckily enough a quick Google search for the patents shown in one of the pictures (patent1, patent2) taught us that a storage circuitry is embedded under the printed USB pads, which may imply that the team had an Application-Specific Integrated Circuit (ASIC) designed or that they simply found one they could use for their own purposes. From the video we learn that ‘each card has a unique ID and can individually be programmed’ (the card, not the UID) and that it can be setup to open any webpage URL. The latter can even be modified after the card has been handed out, hinting that the final recipient would go to a ‘www.swivelcard.com/XXXX” type of address. We therefore got confused by

Imagine giving your business card with pictures, videos, presentations, and websites for the recipient to interact with!

paragraph that the project description contains.

This leads us to one key question we have: what kind of USB drive can make a given user visit a particular website, given that he may have Linux, Windows, Mac or any other OS? They all have similar USB enumeration processes and different key strokes to launch a browser… our wild guess is that it may be detected as storage with a single html file in it. Unfortunately for us the USB detection process is not included in the video.

Our final question: Is it possible to embed both USB and NFC controllers in a thin piece of paper without worrying about broken ICs (see picture above)? NFC enabled passports have obviously been around for a long time but we couldn’t find the same for USB drives.

Possible or not, we would definitely love having one in our hands!

Edit: One of our kind readers pointed out that this campaign actually is a re-launch of a failed indiegogo one which provides more details about the technology and confirms our assumptions.

NFC Ring Lock Box

August 10, 2014 by Rick Osgood 13 Comments

NFC Ring Lock Box

[Nairod785] wanted to build a lock box that would lock from the inside. He started with an inexpensive, plain wooden box. This kept the cost down but would also allow him to easily decorate the box later on using a wood burning tool.

To keep the box locked, he installed a simple latch on the inside. The latch is connected to a servo with string. When the servo rotates in one direction, it pulls the string and releases the latch. When the servo is rotated in the opposite direction, the latch closes and locks the box once again.

If you are going to have a locked box, then you are also going to need a key to open it. [Nairod785] used a ring with a built-in NFC tag, similar to the ring featured back in March. Inside of the box is a PN532 NFC module. The walls of the box were a little too thick for the reader to detect the ring, so [Nairod785] had to scratch the wall thickness down a bit. The NFC module is connected to an Arduino Nano. Communications are handled with I2C.

The NFC ring actually has two different NFC tags in it; one on each side. [Nairod785] had to program both of the tag ID’s into the Arduino to ensure that the ring would work no matter the orientation.

The system is powered by a small rechargeable 5V battery. [Nairod785] wired up a USB plug flush with the box wall so he can easily charge up the battery while the box is locked. It also allows him to reprogram the Arduino if he feels so inclined. There is also a power switch on the side to conserve energy.

The RC White House Robot

July 27, 2014 by Matt Terndrup 6 Comments

IMG_20140726_124812_164

This remote controlled, Arduino-based robot was created by a young student named [Quin] who likes to teach electronics classes at hackerspaces. It is an adaptation of this awesome, fast, fully autonomous mini Roomba that has since driven its way into the Presidential building during the 1st ever White House Maker Faire.

The quick, little device uses a robot chassis kit with an XBee wireless module so that the controller and the robot can be connected together. An NFC Shield was hacked and split in half so that the wires could be soldered in place.

[Quin]’s goal was to develop a fun game that records the number of times the robot drives over NFC tags laid across a flat surface. Points are shown in the form of blinking lights that illuminate when the device goes over the sensors, keeping track of the score.

The controller container was made with an open source 3D printer called a Bukobot. The enclosure holds an Arduino and another XBee shield along with a joystick and a neopixel ring, giving it a nice polished look complete with a circle of beautiful, flashing LED’s.

Continue reading “The RC White House Robot” →

The I2C Programmable NFC Tag

May 30, 2014 by Brian Benchoff 22 Comments

NFC NFC tags are cool, but programming them to do your bidding – whether unlocking your computer, making an Arduino vending machine, or a smart home application – requires using an NFC device to program the tag over the air. An NFC tag programmable with any ‘ol microcontroller would certainly have some interesting applications, and Elecfreaks’ DNFC tag is just the thing to test out these ideas.

While NFC tags are reprogrammable, reprogramming them requires an NFC controller, be that through a dedicated hardware, a phone, or an Arduino shield. The DNFC tag is reprogrammable with a microcontroller with an I2C interface thanks to TI’s RF430CL330H dynamic NFC transponder IC. It still does everything you would expect from a NFC tag – MIFARE compatible. NDEF reading and writing, and everything else – but you can program it through an Arduino, Pi, or any other board with an I2C interface.

TI has an app note on using the chip inside the DNFC for automatic Bluetooth pairing, and Elecfreaks themselves have a few use cases in mind that include putting WiFi credentials on an Arduino board without putting the SSID in code and other Internet of Things™ applications. We’re thinking this is one of those devices that is eminently useful, but for something we just can’t think of off the top of your head. If you’ve got an idea for how to use an I2C programmable NFC tag, drop a note in the comments.

Elecfreaks is doing an Indiegogo campaign for the DNFC, $13 for one. I picked one up, but it’s flexible funding, so buy it or don’t. I don’t care.

Hackaday Links: May 18, 2014

May 18, 2014 by Brian Benchoff 9 Comments

Think the original Pong is cool? How about point to point Pong? [v8ltd] did it in three months, soldering all the leads directly to the chip pins. No sockets required. It’s insane, awesome, a masterpiece of craftsmanship, and surprising it works.

[Jeremy Cook] is building a servo-powered light graffiti thing and needed a laser diode. How do you control a laser pointer with a microcontroller? Here’s how. They’re finicky little buggers, but if you get the three-pack from Amazon like [Jeremy] did, you get three chances to get it right.

NFC tags in everything! [Becky] at Adafruit is putting them in everything. Inside 3D printed rings, glued onto rings, and something really clever: glued to your thumbnail with nail polish. Now you can unlock your phone with your thumb instead of your index finger.

Photographs capture still frames, but wouldn’t it be great if a camera could capture moving images? No, we’re not talking about video because this is the Internet where every possible emotion, reaction, and situation can be expressed with an animated GIF. Meet OTTO, the camera that captures animated GIFs! It’s powered by the Raspberry Pi compute module, so that’s interesting.

[Nate] was getting tired of end mills rolling around his bench. That’s a bad thing. He came up with a solution, though: Mill a piece of plywood into a tray to hold end mills.

The Da Vinci printer, a printer that only costs $500 because they’re banking on the Gillette model, has been cracked wide open by resetting the DRM, getting rid of the proprietary host software, and unbricking the device. Now there’s a concerted effort to develop custom firmware for the Da Vinci printer. It’s extraordinarily bare bones right now, but the pins on the microcontroller are mapped, and RepRap firmwares are extremely modular.

Upgrade Your Garage Door With Arduino And RFID

May 13, 2014 by Rick Osgood 17 Comments

RFID Garage Door Opener

[Jason] really wanted to build an RFID controlled garage door opener and decided to turn to Arduino to get the job done. For someone who’s never worked with an Arduino before, he really seemed to know what he was doing.

The Arduino acts as the brains of the operation while an off-the-shelf NFC/RFID reader module is used to read the RFID tags. To add new keys to the system, [Jason] simply swipes his “master” RFID key. An indicator LED lights up and a piezo speaker beeps, letting you know that the system is ready to read a new key. Once the new key is read, the address is stored on an EEPROM. From that point forward the new key is permitted to activate the system.

Whenever a valid key is swiped, the Arduino triggers a relay which can then be used to control just about anything. In this case, [Jason] plans to use it to control his garage door. The system also has a few manual controls. First is the reset button. If this button is held down for two seconds, all of the keys from the EEPROM are erased. This button would obviously only be available to people who are already inside the garage. There is also a DIP switch that allows the user to select how long the relay circuit should remain open. This is configurable in increments of 100ms.

For now the circuit is wired up on a couple of breadboards, but it might be a good idea to use something more permanent. [Jason] could always take it a step further and learn to etch his own PCB’s. Or he could even design a board in Eagle CAD and order a real printed board. Don’t miss the video description of the RFID system below. Continue reading “Upgrade Your Garage Door With Arduino And RFID” →