Emulator for Tag Devices, Operating Without Power Source
In the world of near field communication (NFC), a new innovation is making waves - the power-free NFC tag emulator. This device, different from devices like the Flipper Zero, emulates an NFC tag without the need for external power.
The Power-Free Tag Emulator
The power-free tag emulator is a board that uses NFC receiver hardware, specifically an NFC antenna coil tuned to 13.56 MHz and capacitors to form a resonant LC circuit. This coil picks up the RF field energy from an NFC reader. The power-free tag emulator harvests this energy to power a low-power microcontroller, the CW32L010 from Wuhan Xinyuan Semiconductor, an ARM Cortex M0+ based device.
The microcontroller runs low-power firmware to emulate the desired NFC tag protocol, such as ISO14443. It uses its I/O pin(s) to modulate the load on the antenna, sending data back by changing the coil's impedance in synchronization with NFC protocol timings.
Design and Implementation
The general steps for creating a power-free NFC tag emulator include:
- NFC Receiver Coil and Analog Front-End: Design an NFC antenna coil with an appropriate matching network.
- Power Harvesting Circuit: Rectify and regulate the AC signal induced in the coil to generate a stable DC voltage sufficient to operate the CW32L010 MCU.
- Microcontroller (CW32L010): Write firmware to implement the NFC tag emulation standards.
- Communication Handling: Use a GPIO pin with a coil load modulation circuit (transistor or FET) to emulate the communication back to the reader.
For simulation and validation, tools such as InfineonSpice can help model and optimize analog sections (antenna matching, rectifier, load modulation) before hardware build.
GitHub Repository
The power-free tag emulator design, as presented in the GitHub repository, only provides a PCB layout, not a circuit diagram. This may require users to provide their own circuit design for the NFC receiver. It's worth noting that the lack of a circuit diagram in the GitHub repository may be unintentional.
Potential Applications
The power-free tag emulator design could inspire ideas for creating an NFC receiver and potentially connecting it to a microcontroller. The ability to run emulation code opens up a world of possibilities, from creating custom tags to testing NFC systems without the need for physical tags.
In summary, the power-free NFC tag emulator circuit combines an NFC resonant receiver coil for harvesting RF energy, a power conditioning stage to supply the CW32L010 microcontroller, and firmware-controlled load modulation for tag emulation. The implementation requires careful analog design for energy harvesting and precise timing and control firmware in the MCU.
With this guide, you now have a starting point for creating your own power-free NFC tag emulator. Happy tinkering!
- The power-free NFC tag emulator, utilizing hardware components such as an NFC antenna coil and a low-power microcontroller, emulates an NFC tag without requiring external power, making it a valuable addition to the world of electronics and gadgets that leverage data-and-cloud-computing technology.
- In manufacturing the power-free NFC tag emulator, the key steps include designing an NFC antenna coil and its matching network, rectifying and regulating the AC signal to power the microcontroller, writing firmware for NFC tag emulation standards, and employing a GPIO pin with a coil load modulation circuit for communication.
- By exploring the power-free NFC tag emulator, one can imagine innovative applications in the realm of electronics and computing, such as developing custom NFC tags, and testing NFC systems using gadgets running emulation code, all without the need for physical tags.
