STMicroelectronics – Data Exchange with Smart Meters using ST M24LR Dual Interface EEPROM

The Near Field Communication (NFC) link of ST’s M24LR series of Dynamic NFC/RFID tags enables utility companies and their customers to read their meter by simply approaching a smartphone. On the production line, the wireless and serial communication offered by M24LR series devices enables the setting of parameters and calibration values thus increasing flexibility and traceability. During installation, the smart meter communicates with the installer, who sets the code that will activate it, then in normal use it can communicate with the consumer who wants to check his loading curve or energy consumption.

Information stored in smartmeters includes documentation, localization of the meter and specific settings linked to the consumer consumption. The M24LR series device can act as the black box of the meter, storing errors, logins and verification dates. The NFC interface is complementary to the Power Line, Zigbee or Sub Giga Hertz RF communication as a dedicated interface for commissioning and to simplify pairing with the main RF communication.

Features of the M24LR Dual Interface EEPROM:

I2C interface:

  • Two-wire I2C serial interface supports 400 kHz protocol
  • Single supply voltage: 1.8 V to 5.5 V
  • Byte and Page Write (up to 4 bytes)
  • Random and Sequential read modes
  • Self-timed programming cycle
  • Automatic address incrementing
  • Enhanced ESD/latch-up protection
  • I²C timeout

Contactless interface:

  • ISO 15693 and ISO 18000-3 mode 1 compatible
  • 13.56 MHz ± 7 kHz carrier frequency
  • To tag: 10% or 100% ASK modulation using 1/4 (26 Kbit/s) or 1/256 (1.6 Kbit/s) pulse position coding
  • From tag: load modulation using Manchester coding with 423 kHz and 484 kHz subcarriers in low (6.6 kbit/s) or high (26 kbit/s) data rate mode. Supports the 53 kbit/s data rate with Fast commands
  • Internal tuning capacitance: 27.5 pF
  • 64-bit unique identifier (UID)
  • Read Block & Write (32-bit blocks)

Digital output pin:

  • User configurable pin: RF write in progress or RF busy mode

Energy harvesting:

  • Analog pin for energy harvesting
  • 4 sink current configurable ranges


  • 4/16/64-Kbit EEPROM
  • Write time: I2C: 5 ms (max.) / RF: 5.75 ms including the internal Verify time
  • More than 1 million write cycles
  • More than 40-year data retention
  • Multiple password protection in RF mode
  • Single password protection in I2C mode

How to Start:

See also

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