EEPROM read and write in Arduino - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is EEPROM in Arduino?

EEPROM stands for Electrically Erasable Programmable Read-Only Memory. It is a small memory inside the Arduino that keeps data even when the power is off.

beginner

How do you write a byte to EEPROM in Arduino?

Use the function EEPROM.write(address, value); where address is the memory location and value is the byte to store.

beginner

How do you read a byte from EEPROM in Arduino?

Use the function EEPROM.read(address); where address is the memory location. It returns the stored byte.

intermediate

Why should you be careful when writing to EEPROM?

EEPROM has a limited number of write cycles (usually 100,000). Writing too often can wear it out and cause data loss.

intermediate

What is the difference between EEPROM.write() and EEPROM.update()?

EEPROM.write() writes a byte no matter what. EEPROM.update() writes only if the new value is different, saving write cycles.

Which Arduino library is used to access EEPROM?

A EEPROM

B Wire

C SPI

D Servo

The EEPROM library provides functions to read and write EEPROM memory.

What does EEPROM.read(10) do?

A Writes the value 10 to EEPROM

B Reads the byte stored at address 10 in EEPROM

C Deletes data at address 10

D Initializes EEPROM

EEPROM.read(address) returns the byte stored at the given address.

Why use EEPROM.update() instead of EEPROM.write()?

A To erase EEPROM

B To read data faster

C To save EEPROM write cycles by writing only if data changes

D To increase EEPROM size

EEPROM.update() writes only if the new value differs, reducing wear.

What happens to EEPROM data when Arduino is powered off?

A Data is erased

B Data is backed up to SD card

C Data is corrupted

D Data is kept intact

EEPROM retains data even when power is off.

What is a typical limit for EEPROM write cycles?

A 100,000 writes

B 10 writes

C 1,000,000 writes

D Unlimited writes

EEPROM usually supports about 100,000 write cycles before wearing out.

Explain how to store and retrieve a byte value using Arduino EEPROM.

Think about how you save and get data from a small notebook.

Describe why it is important to minimize writes to EEPROM and how to do it.

Imagine a pencil that can only be sharpened a few times.