I2C_EEPROM

Arduino Library for external I2C EEPROM - 24LC256, 24LC64

Description

This library is to access external I2C EEPROM up to 64KB (= 512 Kbit) in size.

The I2C_eeprom_cyclic_store interface is documented here

Interface

Constructor

• I2C_eeprom(deviceAddress) constructor.
• bool begin() initializes the I2C bus and checks if the device is available on the I2C bus.
• bool begin(sda, scl) idem for ESP32 / ESP8266 and alike.
• bool isConnected() test to see if device is on the bus.

Core functions

• int writeByte(memoryAddress, value) write a single byte to the specified memory address.
• int writeBlock(memoryAddress, buffer, length) write a buffer starting at the specified memory address.
• int setBlock(memoryAddress, value, length) writes the same byte to length places starting at the specified memory address. Returns 0 if OK.
• uint8_t readByte(memoryAddress) read a single byte from a given address
• uint16_treadBlock(memoryAddress, buffer, length) read length bytes into buffer starting at specified memory address. Returns the number of bytes read, which should be length.
• int updateByte(memoryAddress, value) write a single byte, but only if changed. Returns 0 if value was same or write succeeded.

Other

• int determineSize(bool debug = false) function that determins the size of the EEPROM by detecting when a memory address is folded upon memory address divided by 2. It is based upon the behavior that memory wraps around. The debug flag gives output to Serial.

return value	Size in KB	Notes
-1	could not connect	check device address / wiring
1 .. 64	1 KB .. 64 KB
128	128 bytes
256	256 bytes
512	512 bytes

The function cannot detect smaller than 128 bit EEPROMS (yet).

Warning: this function has changed in 1.3.2 and is not tested for all sizes.

Limitation

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

Future

• look into support of > 64KB EEPROM
• improve error handling, write functions should return bytes written or so.
• what can we do with the print interface? (investigate)
• Wire0 .. WireN support
• investigate multi-EEPROM storage,
• investigate format / clear all function.

Operational

See examples