A golden Jolly Wrencher SAO that works as an NFC tag for sharing contact info.

2024 SAO Contest: The Jolly Tagger Is A Golden Way To Share Info

September 19, 2024 by Kristina Panos 16 Comments

For this contest, we’re asking you to come up with the best SAO you can think of that does something cool. What could be cooler than sharing your contact information all over Supercon and beyond with a tap of a Jolly Wrencher? It’s way better than just some sticker, and with the extra solder pad on the back, you can turn it into a pin once the con is over. Contact data can be uploaded over I²C.

An antenna coil PCB trace as generated by a KiCad plugin. — The KiCad-generated coil.

Here, [Phil Weasel] seeks to answer the question of whether one can make a working NFC tag with the M24LR04E IC, using a PCB trace as a coil. If there is an issue, it’s probably going to be that copper plane inside the antenna.

Designing the antenna itself proved fairly easy after checking the datasheet for the internal tuning capacitance (~27.5 pF), verifying the frequency of NFC (~13.56 MHz), and doing the math to find the inductance needed. After confirming everything in LTSpice, [Phil] used a PCB coil calculator and let the KiCad coil generator draw it out.

Did we mention the Jolly Wrencher is backlit by four side-mounted LEDs? Because what’s an SAO without a few blinkenlights?

Exploring TapTo NFC Integration On The MiSTer

September 15, 2024 by Dave Rowntree 14 Comments

[Ken] from the YouTube channel What’s Ken Making is back with another MiSTer video detailing the TapTo project and its integration into MiSTer. MiSTer, as some may recall, is a set of FPGA images and a supporting ecosystem for the Terasic DE10-Nano FPGA board, which hosts the very capable Altera Cyclone V FPGA.

The concept behind TapTo is to use NFC cards, stickers, and other such objects to launch games and particular key sequences. This allows an NFC card to be programmed with the required FPGA core and game image. The TapTo service runs on the MiSTer, waiting for NFC events and launching the appropriate actions when it reads a card. [Ken] demonstrates many such usage scenarios, from launching games quickly and easily with a physical ‘game card’ to adding arcade credits and even activating cheat codes.

As [Ken] points out, this opens some exciting possibilities concerning physical interactivity and would be a real bonus for people less able-bodied to access these gaming systems. It was fun to see how the Nintendo Amiibo figures and some neat integration projects like the dummy floppy disk drive could be used.

TapTo is a software project primarily for the MiSTer system, but ports are underway for Windows, the MiSTex, and there’s a working Commodore 64 game loader using the TeensyROM, which supports TapTo. For more information, check out the TapTo project GitHub page.

We’ve covered the MiSTer a few times before, but boy, do we have a lot of NFC hacks. Here’s an NFC ring and a DIY NFC tag, just for starters.

Continue reading “Exploring TapTo NFC Integration On The MiSTer” →

As Cheap As Chips: The MiFare Ultra Light Gets A Closer Look

June 26, 2024 by Jenny List 7 Comments

If you take public transport in many of the world’s cities, your ticket will be an NFC card which you scan to gain access to the train or bus. These cards are disposable, so whatever technology they use must be astonishingly cheap. It’s one of these which [Ken Shirriff] has turned his microscope upon, a Montreal Métro ticket, and his examination of the MiFare Ultra Light it contains is well worth a read.

The cardboard surface can be stripped away from the card to reveal a plastic layer with a foil tuned circuit antenna. The chip itself is a barely-discernible dot in one corner. For those who like folksy measurements, smaller than a grain of salt. On it is an EEPROM to store its payload data, but perhaps the most interest lies in the support circuitry. As an NFC chip this has a lot of RF circuitry, as well as a charge pump to generate the extra voltages to charge the EEPROM. In both cases the use of switched capacitors plays a part in their construction, in the RF section to vary the load on the reader in order to transmit data.

He does a calculation on the cost of each chip, these are sold by the wafer with each wafer having around 100000 chips, and comes up with a cost-per-chip of about nine cents. Truly cheap as chips!

If NFC technology interests you, we’ve taken a deep dive into their antennas in the past.

Inside NFC

June 24, 2024 by Al Williams 7 Comments

[Ken Shirriff] likes to take chips apart and this time his target is an NFC chip used in Montreal transit system tickets. As you might expect, the tickets are tiny, cheap, and don’t have any batteries. So how does it work?

The chip itself is tiny at 570 µm × 485 µm. [Ken] compares it to a grain of salt. The ticket has a thin plastic core with a comparatively giant antenna onboard.

Continue reading “Inside NFC” →

Mobile phone reading an NFC tag with information on a garden plant

NFC Puts A Stake In The Ground

August 15, 2023 by Michael Shaub 21 Comments

Sometimes we have a new part or piece of tech that we want to use, and it feels like a solution looking for a problem. Upon first encountering NFC Tags, [nalanj] was looking for an application and thought they might make a great update to old-fashioned plant markers in a garden. Those are usually small and, being outside 24/7, the elements tend to wear away at what little information they hold.

[nalanj] used a freeform data structuring service called Cardinal to set up text information fields for each plant and even photos. Once a template has been created, every entry gets a unique URL that’s perfect for writing to an NFC tag. See the blog post on Cardinal’s site for the whole process, the thought behind the physical design of the NFC tag holder, and a great application of a pause in the 3D print to encapsulate the tags.

NFC tags are super hackable, though, so you don’t have to limit yourself to lookups in a plant database. Heck, you could throw away your door keys.

Adding Smart Watch Features To Vintage Casio

July 3, 2023 by Bryan Cockfield 16 Comments

[Matteo] has been a fan of the Casio F-91W wristwatch virtually since its release in 1989. And not without good reason, either. The watch boasts reliable timekeeping and extremely long battery life thanks to a modern quartz crystal and has just about every feature needed in a watch such as an alarm and a timer. And, since it’s been in use since the 80s, it’s also a device built to last. The only thing that’s really missing from it, at least as far as [Matteo] was concerned, was a contactless payment ability.

Contactless systems use near-field communication (NFC) to remotely power a small chip via a radio antenna when in close proximity. All that’s really required for a system like this is to figure out a way to get a chip and an antenna and to place them inside a new device. [Matteo] scavenges the chip from a payment card, but then builds a new antenna by hand in order to ensure that it fits into the smaller watch face. Using a NanoVNA as an antenna analyzer he is able to recreate the performance of the original antenna setup in the smaller form factor and verify everything works before sealing it all up in a 3D-printed enclosure that sandwiches the watch.

There are a few reasons why using a contactless payment system with a watch like this, instead of relying on a smartwatch, might be preferential. For one, [Matteo] hopes to explore the idea that one of the physical buttons on the watch could be used to physically disable the device to reduce pickpocketing risk if needed. It’s also good to not have to buy the latest high-dollar tech gadget just for conveniences like this too, but we’ve seen in the past that it’s not too hard just to get these systems out of their cards in the first place.

Hacking A “Smart” Electric Toothbrush To Reset Its Usage Counter

May 27, 2023 by Maya Posch 46 Comments

The visible circuitry inside the brush head.

Following the trend of stuffing more electronics in everyday devices, the new Philips Sonicare electric toothbrush that [Cyrill Künzi] purchased ended up having a ‘brush head replacement reminder’ feature that wasn’t simply a timer in the handle or base of the unit, but ended up involving an NFC chip embedded in every single brush head containing the usage timer for that particular head. Naturally, this asked for it to be solidly reverse-engineered and hacked.

The NFC chip inside the brush head turned out to be an NXP NTAG213, with the head happily communicating with the NFC reader in a smartphone and the NFC Tools app. This also revealed the memory layout and a few sections that had write access protected by a password, one of which was likely to be the counter. This turned out to be address 0x24, with a few experiments showing the 32-bit value at this address counting the seconds the brush head had been used.

Continue reading “Hacking A “Smart” Electric Toothbrush To Reset Its Usage Counter” →