## Overview of the M24LR04E-R The **M24LR04E-R** is a unique electronic component developed by STMicroelectronics. It is categorized as a **Dynamic NFC/RFID Tag IC**. What makes it special is its "Dual Interface" capability, allowing it to communicate both wirelessly (via RFID) and wired (via I2C). --- ### 1. Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Memory Size** | 4 Kbits (512 bytes) of EEPROM | | **RFID Interface** | ISO/IEC 15693 and ISO 18000-3 Mode 1 | | **I2C Interface** | Two-wire serial interface (400 kHz) | | **Operating Voltage** | 1.8V to 5.5V | | **Operating Frequency** | 13.56 MHz (HF) | | **Data Retention** | 40 years | | **Write Endurance** | 1 million cycles | --- ### 2. Functional Blocks and Features #### A. Dual Interface The device acts as a bridge between two worlds: * **Contactless (RF):** It can be read and written by an RFID reader or an NFC-enabled smartphone. * **Contact (I2C):** It can be accessed by a local microcontroller (MCU) just like a standard serial EEPROM. #### B. Energy Harvesting One of the standout features of the M24LR04E-R is its **Energy Harvesting** mode. When the chip is placed in an induction field (from an NFC phone or RFID reader), it can convert that RF energy into a DC voltage. This voltage is output on the `V_out` pin and can be used to power a low-power microcontroller or an LED, effectively allowing a device to operate without a battery. #### C. RF Status / Interrupt Pin The device includes a **GPO (General Purpose Output)** pin. This pin can be configured to signal the host microcontroller when a specific event occurs, such as: * The start of an RF session. * The completion of a write command via RF. * The presence of an RF field. #### D. Password Protection To ensure data security, the memory is divided into sectors that can be protected by a 32-bit password, preventing unauthorized access via the RF interface. --- ### 3. Pin Configuration | Pin Name | Function | | :--- | :--- | | **AC0 / AC1** | Antenna connection pins (to an external coil). | | **V_out** | Energy harvesting output voltage. | | **SCL / SDA** | I2C clock and data lines. | | **V_cc** | Power supply (1.8V to 5.5V). | | **GPO** | Configurable interrupt/status output. | --- ### 4. Common Applications * **Industrial Automation:** Updating configuration parameters in a machine without opening its casing. * **Medical Devices:** Storing patient data or usage logs that can be read even if the device's battery is dead. * **Consumer Electronics:** Simplifies Bluetooth/Wi-Fi pairing via NFC (Handover). * **Smart Labels:** Electronic Shelf Labels (ESL) that update prices wirelessly.