### M24C08-R: 8-Kbit Serial I²C Bus EEPROM The **M24C08-R** is a specific variant of electrically erasable programmable read-only memory (EEPROM) manufactured by STMicroelectronics. It is widely used for parameter storage in consumer electronics, industrial controls, and medical devices. --- ### 1. Key Technical Specifications The "R" suffix specifically denotes a device capable of operating at a low voltage range (1.8V to 5.5V). | Feature | Specification | | :--- | :--- | | **Memory Size** | 8 Kbits (1024 x 8 bits) | | **Interface** | I²C (Inter-Integrated Circuit) | | **Supply Voltage (Vcc)** | 1.8 V to 5.5 V | | **Clock Frequency** | 400 kHz (Fast Mode) | | **Write Cycle Time** | 5 ms (Maximum) | | **Endurance** | 4 Million Write Cycles | | **Data Retention** | 200 Years | | **Operating Temp** | -40°C to +85°C | --- ### 2. Pin Configuration and Functions The M24C08-R is typically found in SO8, TSSOP8, or UFDFPN8 packages. | Pin Name | Type | Description | | :--- | :--- | :--- | | **SDA** | I/O | Serial Data: Transfers data in and out of the device. | | **SCL** | Input | Serial Clock: Synchronizes the data transfer. | | **WC** | Input | Write Control: Hardware protection. Connect to Vcc to disable writes. | | **VCC** | Power | Supply Voltage (1.8V - 5.5V). | | **VSS** | Power | Ground (0V). | | **E2** | Input | Chip Enable: Used for addressing (E0 and E1 are usually not used in 8Kb models). | --- ### 3. Core Functional Features #### I²C Protocol Handling The device acts as a **Slave** on the I²C bus. Because it is an 8-Kbit device, it requires 10 bits of addressing. The memory is organized into four blocks of 256 bytes each. To access these blocks, the device uses a specific addressing scheme where bits of the "Device Select Code" determine which 256-byte page is being accessed. #### Write Protection (WC Pin) The **Write Control (WC)** pin provides hardware data protection: * **WC = High (Vcc):** The entire memory contents are protected (Read-only mode). * **WC = Low (Vss):** The memory is unprotected (Normal Read/Write mode). #### Page Write Mode The device supports a **16-byte Page Write**. This allows the microcontroller to send up to 16 bytes in a single I²C transaction, significantly improving data throughput compared to writing one byte at a time. --- ### 4. Typical Application Circuit When integrating the M24C08-R, pull-up resistors are required on the SDA and SCL lines because they are open-drain outputs. ```c // Pseudo-code for writing a byte to M24C08-R I2C_Start(); I2C_Send_Address(0xA0); // Device Address (0) + Write Bit I2C_Send_Byte(0x05); // Memory Address 0x05 I2C_Send_Data(0x42); // Data to store I2C_Stop(); Delay(5ms); // Wait for internal write cycle ``` ---