If you want to store calibration values, Mac addresses, unsecure access tokens or other unique identifiers, EEPROM memory is a great option. EEPROM is durable and does not need to be written in pages - a single byte can be written at the same time (unlike flash memory). EEPROM memory remains retained even when power is empty, and can literally be overwritten a million times. Some microcontrollers, such as the ATmega328, have built-in EEPROM, usually about 64 to 1024 bytes of it. But some, especially ARM Cortexs, not! What is then? This is where this Petite Adafruit 24LC32 I2C EEPROM breakout comes into play. With 32 Kbit (4 Kbyte) storage space and handy chainable Stemma QT connectors, it is just the right amount of simple, I2C controllable memory. Because it is a microcontroller or a microcomputer, uploading a new flash memory does not delete the data from this chip. We use the CAT24C32 (or equivalent) EEPROM, internally organized as 4096 words with 8 bits each. It has a writing buffer with 32 byte pages (if you want to write faster than a byte at once). Use 2 to 5 V current/logic and up to 1 MHz clocked I2C. The default I2C address is 0x50 and there are three external address pins / jumpers to enable addressing up to eight EEPROM devices on the same bus. To make things easier and a bit more flexible, we also included SparkFun Qwiic compatible STEMMA QT connectors for the I2C bus so you dont even have to solder. Simply plug in a compatible cable and attach it to your MCU of your choice, and you can store and retrieve it from a reliable and durable EEPROM. QT cable is not included, but we have a variety in the shop.