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  Date: 18/02/2014

NFC Tag; an important component for IoT

Payments, banking, cashless shopping and access control are currently major areas of growth and these are set to become even more specialized than they are at the moment. NFC a wireless communications technology that allows two devices to communicate when they are in close proximity, has huge scope in India - as from Indian consumer perspective people love sharing. Soon NFC it will contribute to connecting objects to the "Internet of Things", which will change the way consumers interact with those connected things.

ST aims to drive this change with its new M24SR family of “dynamic NFC tag” memories that allow any device, including printers, fitness watches, microwave ovens, smart electricity meters or digital cameras to feature built-in NFC connectivity, thereby allowing it to communicate with a smartphone that almost touches it.

In the M24SR family, the NVM is implemented as EEPROM (Electrically Erasable Programmable Read-Only Memory) in sizes ranging from 2 to 64Kbit, covering all current market demands. ST is the world leader in EEPROM technology and the world’s largest supplier of EEPROM memories.

The wireless interface is fully compatible with the ISO14443-A protocol that enables data rates up to 106kb/s, while the I2C interface operates at speeds up to 1MHz, ensuring fast data transfer between the smartphone and the target equipment.

The EEPROM memory bank is preformatted for NFC operation, supporting the NFC Data Exchange Format (NDEF), and uses the latest and most reliable EEPROM technology, with data retention guaranteed for 200 years, one million write-erase cycles, and 128-bit password protection for maximum security.

Offered in compact and cost-effective SO8, TSSOP8 and MLP8 packages, the M24SR devices are now available in samples for OEM customers.

In an exclusive Q&A with EE Herald, Mr. Amit Sethi, Product Marketing Manager -Memories and the RFID, STMicroelectronics India provides us some technical insights on M24SR family. Some excerpts:

1. Can you explain more on ISO 14443 RF interface?

ISO14443 is an ISO standard for proximity card (communication distance up to 10 cm). It uses 13.56 MHz frequency to exchange data @106 kbps, up to 848kbps. NFC forum takes ISO14443 standard as a reference standard for the underlying technology of NFC products.

2. What all kind of data these NFC devices can transfer to other devices?

The M24SR is a dynamic NFC / RFID tag that enables convenient wireless pairing (BT, WIFI) and data exchange between an NFC phone and a micro-controller. The main use cases for data exchange are to update user settings, download data logs download.

3. How many read/writes the EEPROM supports? and other any such reliability specialties of EEPROM?

The EEPROM is specified to 1 million erase-write cycles. Additionally the data retention of the EEPROM is up to 200 years.

4. Can you explain more on RF disable pin, what applications can leverage this feature?

RF disable function is an input pin that allows the MCU or system host to activate or deactivate the RF commands. This feature allows the application to control or stop any RF exchange with a NFC phone or NFC reader.

5. What are the data security features in this chip?

Data stored in the EEPROM memory based on NDEF format can be protected by a 128-bit password. The NDEF file passwords protect both write and read access from RF or I2C from / to an NDEF file. There are separate passwords for Read and Write per NDEF file. A Super User mode allows to read/write in the NDEF file, and to configure the M24SR chipset. It has its own 128-bit password, and can be accessed only through I2C interface.

6. Any successful design wins and products already in the market based on M24SR series?

We’re seeing good traction, but there is nothing we can disclose. M24SR mass-market launch is planned for end of February 2014. Some M24SR samples have been delivered to key customers during Q4 2013 and design / development on going.

7. Can you please explain design aspects for the engineers to add this feature in their product by using ST's NFC chips?

Engineers can replace a standard EEPROM with our M24SR dual interface EEPROM; its I2C HW interface is almost the same as standard EEPROM and they do need to add the RF NFC antenna on the PCB / Flex. Application notes, antenna eDesign suite and reference designs on ST’s website are available to support customers designing their board with an NFC antenna.

8. What are software programming/codes changes required to embed this feature in an embedded system which is not supporting NFC?

From a software point of view, the memory benefits from a file access method, on top of the I2C protocol. This file access method complies with NFC Forum Type 4 Tag operation (protocol to deal with the memory content).
For full compliancy in front of an NFC reader, the data must respect the NDEF data format, as defined by NFC Forum. ST provides source code as examples, for all protocols and data format, in addition to User Manuals and Application Notes, for guidance.

9. What are reference designs made available for this chip?

We have released 3 reference designs based on M24SR product:
o M24SR standard discovery kit: M24SR + STM32F1 + Color display (USB + JTAG interface).
o M24SR premium discovery kit: standard kit + BT / Audio module + Audio headset .
o M24SR reference antennas.

Amit ST
Picture above: Mr. Amit Sethi, Product Marketing Manager -Memories and the RFID, STMicroelectronics India.

At Embedded World 2014, STMicroelectronics said to unveil an easy-access development platform for its M24SR dynamic NFC tags that are now entering volume production in all memory densities and package options. Accelerating the design of IoT applications, ST’s M24SR Discovery Kit contains everything engineers need to start adding NFC connectivity to any kind of electrical device, from fitness watches and loudspeakers to washing machines and water meters.

Picture above: Development Kit based on M24SR
Author: Srinivasa Reddy N
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