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AT24C256 I²C Serial EEPROM Module — 256Kbit (32KB), 3.3V–5V, Arduino Compatible
AT24C256 I²C Serial EEPROM Module 256Kbit (32KB), 3.3V–5V, Arduino Compatible
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AT24C256 I²C Serial EEPROM Module — 256Kbit (32KB), 3.3V–5V, Arduino Compatible
This breakout module is built around the AT24C256 256Kbit (32KB) I²C serial EEPROM IC from Microchip (formerly Atmel). With onboard pull-up resistors, address selection jumpers (A0–A2), and a 3.3V–5V compatible interface, it provides plug-and-play non-volatile data storage for Arduino, ESP32, STM32, and Raspberry Pi projects. Ideal for storing configuration data, calibration values, sensor logs, and user settings that must survive power cycles.
Key Specifications
| Parameter | Value |
|---|---|
| EEPROM IC | AT24C256 (Microchip / Atmel) |
| Capacity | 256Kbit (32KB) |
| Interface | I²C (up to 400kHz fast mode) |
| I²C Address | 0x50–0x57 (set via A0–A2 jumpers) |
| Supply Voltage | 1.8V – 5.5V |
| Page Size | 64 bytes |
| Write Cycle Time | 5ms max |
| Endurance | 1,000,000 erase/write cycles |
| Data Retention | 100 years |
| Module Features | Onboard pull-ups, A0–A2 address jumpers, WP write-protect pin |
Why Choose AT24C256 Module?
- 32KB capacity — stores thousands of sensor readings, configuration structs, or user settings
- 1M write cycle endurance — suitable for frequent data logging without wear concern
- 100-year data retention — reliable long-term non-volatile storage
- Onboard pull-ups — plug directly into I²C bus, no external resistors needed
- Address jumpers — up to 8 modules on one I²C bus (256KB total)
Compatible With
- Arduino: Wire library + EEPROM_I2C or extEEPROM library (address 0x50)
- ESP32 / ESP8266: Wire.h at 3.3V
- STM32: HAL I²C driver
- Raspberry Pi: smbus2 Python library
- MicroPython: machine.I2C + custom AT24Cxxx driver
Frequently Asked Questions
Q: How do I write and read data from AT24C256 with Arduino?
A: Use the extEEPROM library: extEEPROM eep(kbits_256, 1, 64); eep.begin(twiClock400kHz); eep.write(address, data); eep.read(address, buffer, length); The library handles page-write boundaries and 5ms write cycle timing automatically.
Q: What is the difference between AT24C256 and AT24C512?
A: AT24C256 has 256Kbit (32KB) capacity with 64-byte pages. AT24C512 has 512Kbit (64KB) capacity with 128-byte pages. Both use the same I²C protocol and address range (0x50–0x57). Use AT24C512 if you need more than 32KB of storage.
Q: How many AT24C256 modules can I connect to one Arduino I²C bus?
A: Up to 8 modules, using A0–A2 jumpers to set unique addresses (0x50–0x57). This provides 8 × 32KB = 256KB total EEPROM storage on a single I²C bus with just 2 signal wires.
Package Contents
- 1× AT24C256 I²C Serial EEPROM Module (with onboard pull-ups and address jumpers)
