Using a Standard Coil for NFC Tag Implant Reading

NFC reader PCB

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.

Internet-Connected TI-84

sparkbridge3

Just before the days where every high school student had a cell phone, everyone in class had a TI graphing calculator. In some ways this was better than a cell phone: If you wanted to play BlockDude instead of doing trig identities, this was much more discrete. The only downside is that the TI calculators can’t easily communicate to each other like cell phones can. [Christopher] has solved this problem with his latest project which provides Wi-Fi functionality to a TI graphing calculator, and has much greater aspirations than helping teenagers waste time in pre-calculus classes.

The boards are based around a Spark Core Wi-Fi development board which is (appropriately) built around a TI CC3000 chip and a STM32F103 microcontroller. The goal of the project is to connect the calculators directly to the Global CALCnet network without needing a separate computer as a go-between. These boards made it easy to get the original Arduino-based code modified and running on the new hardware.

After a TI-BASIC program is loaded on the graphing calculator, it is able to input the credentials for the LAN and access the internet where all kinds of great calculator resources are available through the Global CALCnet. This is a great project to make the math workhorse of the classroom even more useful to students. Or, if you’re bored with trig identities again, you can also run a port of DOOM.

The ESP8266 Becomes a Terrible Browser

esp

The ESP8266 are making their way over from China and onto the benches of tinkerers around the world for astonishing web-enabled blinking LED projects and the like. [TM] thought he could do something cooler with his WiFi to UART module and decided to turn one into a web browser.

There’s no new code running on the ESP8266 – all the HTML is being pushed through an Arduino Mega, requesting data from a server (in this case our fabulous retro edition), and sending the data to the Arduino serial console. The connection is first initiated with a few AT commands to the ESP module, then connecting to the retro server and finally dumping everything received to the console.

It’s not much – HTML tags are still displayed, and images are of course out of the question. The result, however, isn’t that much different from what you would get from Lynx, meaning now the challenge is open for an Arduino port of this ancient browser.

GCC for the ESP8266 WiFi Module

When we first heard about it a few weeks ago, we knew the ESP8266 UART to WiFi module was a special beast. It was cheap, gave every microcontroller the ability to connect to a WiFi network, and could – possibly – be programmed itself, turning this little module into a complete Internet of Things solution. The only thing preventing the last feature from being realized was the lack of compiler support. This has now changed. The officially unofficial ESP8266 community forums now has a working GCC for the ESP8266.

The ESP8266 most people are getting from China features a Tensilica Xtensa LX3 32-bit SOC clocked at 80 MHz. There’s an SPI flash on the board, containing a few dozen kilobytes of data. Most of this, of course, is the code to run the TCP/IP stack and manage the radio. There are a few k left over – and a few pins – for anyone to add some code and some extended functionality to this module. With the work on GCC for this module, it’ll be just a few days until someone manages to get the most basic project running on this module. By next week, someone will have a video of this module connected to a battery, with a web-enabled blinking LED.

Of course that’s not the only thing this module can do; at less than $5, it will only be a matter of time until sensors are wired in, code written, and a truly affordable IoT sensor platform is created.

If you have a few of these modules sitting around and you’d like to give the new compiler a go, the git is right here.

Atmel and Arduino Announce Wi-Fi Shield 101 at World Maker Faire

Atmel and Arduino teamed up at World Maker Faire to introduce the Wi-Fi shield 101. [Gary] from Atmel gave us the lowdown on this new shield and its components. The shield is a rather spartan affair, carrying only devices of note: an Atmel WINC1500 WiFi module, and an ATECC108 crypto chip.

The WINC1500 is a nifty little WiFi module in its own right. WINC handles IEEE 802.11 b/g/n at up to 72 Mbps. 72Mbps may not sound like much by today’s standards, but it’s plenty fast for most embedded applications. WINC handles all the heavy lifting of the wireless connection. Connectivity is through SPI, UART or I2C, though on the Arduino shield it will be running in SPI mode.

The ATECC108 is a member of Atmel’s “CryptoAuthentication” family. It comes packaged in an 8-pin SOIC, and is compatible with serial I2C EEPROM specifications. Internally the similarities to serial EEPROMs end. The ‘108 has a 256-bit SHA engine in hardware, as well as a Federal Information Processing Standards (FIPS) level random number generator. Atmel sees this chip as being at the core of secure embedded systems. We think it’s pretty darn good, so long as we don’t hear about it at the next DEFCON.

The Wi-Fi shield 101 and associated libraries should be out in January 2015. We can’t wait to see all the new projects (and new ways to blink an LED) the shield will enable.

A 1920’s Doorbell is Upgraded with 2010’s Technology

Doorbell

When you move into an old house, you are bound to have some home repairs in your future. [Ben] discovered this after moving into his home, built in 1929. The house had a mail slot that was in pretty bad shape. The slot was rusted and stuck open, it was covered in old nasty caulk, and it had a built-in doorbell that was no longer functional. [Ben] took it upon himself to fix it up.

The first thing on the agenda was to fix the doorbell. After removing the old one, [Ben] was able to expose the original cloth-insulated wiring. He managed to trace the wires back to his basement and, to his surprise, they seemed to be functional. He replaced the old doorbell button with a new momentary button and then hooked up a DIY doorbell using an XBee radio. [Ben] already had an XBee base station for his Raspberry Pi, so he was wrote a script that could send a notification to his phone whenever the doorbell was pushed.

Unfortunately, the old wiring just didn’t hold up. The push button only worked sporadically. [Ben] ended up purchasing an off the shelf wireless doorbell. He didn’t want to have to stick the included ugly plastic button onto the front of his house though, so [Ben] had to figure out how to trigger the new doorbell using the nice metallic button. He used the macro lens on his iPhone to follow the traces on the PCB until he was able to locate the correct points to trigger the doorbell. Then it was just a matter of a quick soldering job and he had a functional doorbell.

Once the electronics upgrades were complete, he moved on to fixing up the look of the mail slot. He had to remove the rust using a wire brush and sandpaper. Then he gave it a few coats of paint. He replaced the original natural insulation with some spray foam, and removed all the old nasty caulk. The final product looks as good as new and now includes a functional wireless doorbell.

We’re big fans of salvaging old-school home hardware. Another example that comes to mind is this set of door chimes with modernized driver.

ESP8266 Distance Testing

ESP

With progress slowly being made on turning the ESP8266 UART to WiFi module into something great, there is still the question of what the range is for the radio in this tiny IoT wonder. [CNLohr] has some test results for you, and the results are surprisingly good.

Connecting to the WiFi module through a TPLink WR841N router, [CN] as able to ping the module at 479 meters with a huge rubber duck antenna soldered on, or 366 meters with the PCB antenna. Wanting to test out the maximum range, [CN] and his friends dug out a Ubiquiti M2 dish and were able to drive 4.28 kilometers away from the module and still ping it.

Using a dish and a rubber duck antenna is an exercise in excess, though: no one is going to use a dish for an Internet of Things thing, but if you want to carry this experiment to its logical conclusion, there’s no reason to think an ESP8266 won’t connect, so long as you have line of sight and a huge antenna.

There’s still a lot of work to be done on this module. It’s capable of running custom code, and since you can pick this module up for less than $5 USD, it’s an interesting platform for whatever WiFi project you have in mind.

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