I2C_24LC1025 - I2C 1MB EEPROM

Arduino library for for external I2C EEPROM - 24LC1025 and equivalents e.g. 24AA1025/24FC1025.

Description

This library is to access external I2C EEPROM of 128 KB in size, typically the 24LC1025 and equivalents e.g. 24AA1025/24FC1025.

Warning A2 = Non-Configurable Chip Select. This pin must be connected to VCC (+5V). The device will NOT work when this pin floats or is connected to GND (0V).

Interface

The interface is kept quite identical to the I2C_EEPROM library. https://github.com/RobTillaart/I2C_EEPROM

Most important change is 32 bit memory addresses.

Constructor

I2C_24LC1025(uint8_t deviceAddress, TwoWire *wire = &Wire) constructor, optional Wire interface.
bool begin() initializes the I2C bus and checks if the device is available on the I2C bus.
bool begin(uint8_t sda, uint8_t scl) idem for ESP32 / ESP8266 and alike.
bool isConnected() test to see if device is on the bus.

Core functions

int writeByte(uint32_t memoryAddress, uint8_t value) write a single byte to the specified memory address.
int updateByte(uint32_t memoryAddress, uint8_t value) write a single byte, but only if changed. Returns 0 if value was same or write succeeded.
int writeBlock(uint32_t memoryAddress, uint8_t * buffer, uint32_t length) write a buffer starting at the specified memory address.
int updateBlock(uint32_t memoryAddress, uint8_t * buffer, uint32_t length) write a buffer starting at the specified memory address, but only if changed
int setBlock(uint32_t memoryAddress, uint8_t value, uint32_t length) writes the same byte to length places starting at the specified memory address. Returns 0 if OK.
uint8_t readByte(uint32_t memoryAddress) read a single byte from a given address
uint16_t readBlock(uint32_t memoryAddress, uint8_t * buffer, uint32_t length) read length bytes into buffer starting at specified memory address. Returns the number of bytes read, which should be length.

Other

uint32_t getDeviceSize() idem
uint8_t getPageSize() idem
uint32_t getLastWrite() idem

UpdateBlock()

(new since 0.1.3)

The function updateBlock() reads the block of data and compares it with the new values to see if it needs rewriting.

As the function reads/writes the data in blocks with a maximum length of I2C_TWIBUFFERSIZE (== 30 AVR limitation; 128 for ESP32) it does this comparison in chuncks if the length exceeds this number. The result is that an updateBlock() call can result e.g. in 4 reads and only 2 writes under the hood.

If data is changed often between writes, updateBlock() is slower than writeBlock(). So you should verify if your sketch can make use of the advantages of updateBlock()

Limitation

The library does not offer multiple EEPROMS as one continuous storage device.

Future

See I2C EEPROM as this library is following.

Operation

See examples

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