24LC256 EEPROM on Arduino

About: I picked up a few 24LC256 eeproms to get some more external memory for future projects. These eeproms hold around 32Kbytes which is more than enough for a basic data-logger or for storing specific values. You can hookup 4 of these chips together to get a whopping total of 128Kbytes of external memory. These chips are great not only for the memory but also because they are I2C. Don’t let this scare you, there are many libraries for I2C eeprom chips. I2C is also great because it only uses 2 analog pins of your arduino. The I2C pins on the arduino are analog pin 4 and analog pin 5. For this tutorial I followed Hkhijhe example and his functions.

Objective: To connect a I2C eeprom to the Arduino Uno.

Instructions: For the breadboard schematic below for how to connect the 24LC256 to the Arduino.


24LC256 Connections
5Analog Pin 4
6Analog Pin 5

Arduino Code: The following code will write a string to the eeprom and keep repeating it every 2 seconds to the serial port.

Comment with any questions.


One Comments

  • Sushikshitha

    March 13, 2018

    how to retrieve the data(hex data) from 24LC256 external eeprom which is already data(hex data) is stored into external eeprom by arduino due’s using I2C serial communication.


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