A Music Box Commanded By NFC Tags

March 31, 2025 by Lewin Day 7 Comments

[Luca Dentella] recently encountered a toy, which was programmed to read different stories aloud based on the figurine placed on top. It inspired him to build an audio device using the same concept, only with music instead of children’s stories.

The NFC Music Player very much does what it says on the tin. Present it with an NFC card, and it will play the relevant music in turn. An ESP32 WROOM-32E lives at the heart of the build, which is hooked up over I2S with a MAX98357A Class D amplifier for audio output. There’s also an SD card slot for storing all the necessary MP3s, and a PN532 NFC reader for reading the flash cards that activate the various songs. Everything is laced up inside a simple 3D-printed enclosure with a 3-watt full range speaker pumping out the tunes.

It’s an easy build, and a fun one at that—there’s something satisfying about tossing a flash card at a box to trigger a song. Files are on Github for the curious. We’ve featured similar projects before, like the Yaydio—a fun NFC music player for kids. Video after the break.

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Yaydio, A Music Player For Kids

March 29, 2025 by Jenny List 6 Comments

Music consumption has followed a trend over the last decade or more of abandoning physical media for online or streaming alternatives. This can present a problem for young children however, for whom a simpler physical interface may be an easier way to play those tunes. Maintaining a library of CDs is not entirely convenient either, so [JakesMD] has created the Yaydio. It’s a music player for kids, that plays music when a card is inserted in its slot.

As you might expect, the cards themselves do not contain the music. Instead they are NFC cards, and the player starts the corresponding album from its SD card when one is detected. The hardware is simple enough, an Arduino Nano with modules for MP3 playback, NFC reading, seven segment display, and rotary encoder. The whole thing lives in a kid-friendly 3D printed case.

Some thought has been given to easily adding albums and assigning cards to them, making it easy to keep up with the youngster’s tastes. This isn’t the first such kid-friendly music player we’ve seen, but it’s certainly pretty neat.

Close up of a Sony FX-300 'Jackal' radio

Packing Even More Features Into A Classic Radio

January 17, 2025 by Heidi Ulrich 11 Comments

When it comes to hacking niches, breathing new life into vintage devices is always an exciting challenge. [t0mg]’s recent project exemplifies this with his 1978 Sony FX-300 ‘Jackal’ radio. He’d already upgraded the radio in 2021 and turned it into a feature-packed marvel, but there’s always room for improvement.

[t0mg]’s initial 2021 build had its quirks: noisy sound, a subpar display, and a non-functional radio module. Determined to enhance these aspects, he sourced an IPS version of the original 3.2″ ILI9431 LCD, significantly improving viewing angles. To tackle the audio issues, he integrated an M5Stack Atom microcontroller, utilizing its Bluetooth A2DP capabilities to deliver cleaner digital sound via I2S to the Teensy audio board. The Teensy itself got a complete wire overhaul just for the sake of good craftmanship.

The new setup also enabled the display of song metadata. Additionally, [t0mg] incorporated a dedicated Arduino Nano clone to manage inputs, streamlining the overall design. The revamped ‘Jackal’ now boasts a bunch of impressive features such as displaying RDS data for FM stations, voice recording, and an NFC reader for personalized playlists.

If you’re into radio makeovers, look into this post for a real golden oldie, or start out with the basics. For [t0mg]’s earlier improved version of this Jackal, read our article on it here.

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ATTiny NFC Thermometer keychain with keys

Tiny NFC-Powered Keychain Thermometer

December 8, 2024 by Heidi Ulrich 9 Comments

What if your keychain could tell you the temperature, all while staying battery-free? That’s the essence of this innovative keychain ‘NFC_temp’ by [bjorn]. This nifty gadget harnesses energy from an NFC field—like the one created by your smartphone—to power itself just long enough to take a precise temperature reading. Using components like an ATTiny1626 microcontroller, a TMP117 thermometer, and an RF430CL330H NFC IC, NFC_temp cleverly stores harvested power in a capacitor to function autonomously.

The most impressive part? This palm-sized device (18×40 mm) uses a self-designed 13.56 MHz antenna to draw energy from NFC readers. The temperature is then displayed on the reader, with an impressive accuracy of ±0.1 °C. Creator [bjorn] even shared challenges, like switching from an analog sensor due to voltage instability, which ultimately led to his choice of the TMP117. Android phones work best with the tag, while iOS devices require a bit more angling for reliable detection.

Projects like NFC_temp underscore the creativity within open source. It’s a brilliant nod to the future of passive, wireless, energy-efficient designs. Since many of us will all be spending a lot of time around the Christmas tree this month, why not fit it in a bauble?

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.

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

June 26, 2024 by Jenny List 8 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.