This article provides a detailed explanation of the I2C communication protocol used for reading and writing data to the AT24C256 EEPROM using a microcontroller. The program is designed for general-purpose use with a range of 24C01 to 24C256 EEPROMs, offering flexibility and ease of integration into various embedded systems.
The program includes five main parameters that define the operation: a pointer to the data buffer, the number of bytes to read or write, the starting address in the EEPROM, the control byte, and the specific EEPROM type. These parameters allow the function to adapt to different memory sizes and configurations efficiently.
The code is well-structured, ensuring clarity and maintainability. It also features strong fault tolerance, making it suitable for real-world applications where reliability is critical. The program uses minimal machine code, which helps in reducing execution time and resource usage on microcontrollers with limited processing power.
Key variables include DataBuff, which points to the input/output buffer; Length, indicating the number of bytes to transfer; Addr, representing the internal address of the EEPROM; and ControlByte, which determines the read/write mode and chip selection. The ControlByte format follows a standard I2C protocol, typically structured as (1)(0)(1)(0)(A2)(A1)(A0)(R/W), where R/W=1 indicates a read operation, and R/W=0 means a write operation.
The enumeration variable 'enum' specifies the EEPROM type, such as AT2401 to AT24256, corresponding to the AT24C series. The return value is a bit variable: 0 means the operation was successful, while 1 indicates an error. Additionally, an error counter is implemented to prevent infinite retries, aborting the operation if the maximum number of attempts is reached.
SDA and SCL lines are user-defined based on the microcontroller's setup. For smaller EEPROMs like 1K, 2K, 4K, 8K, and 16K bits, an 8-bit address is used. For larger chips like 32K bits and above, two 8-bit addresses are required. Some EEPROMs, such as 4K, 8K, and 16K, use page addressing for more efficient memory management.
Complete Program Code
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