DS3231 RTC I2C Module—Precision Real-Time Clock⏱️

The DS3231 RTC I2C Module is a high-accuracy real-time clock breakout that integrates a DS3231 temperature-compensated RTC and a 24C32 (32 Kbit) EEPROM. Designed for reliable timekeeping in embedded systems, this module is ideal for Arduino, Raspberry Pi, and other microcontroller-based projects that require precise time and non-volatile data storage. It communicates via the standard I2C interface and includes a 20 mm coin-cell holder for RTC backup power.

🧰 Highlights

• Temperature-Compensated Crystal Oscillator (TCXO) for high-precision timekeeping
• 24C32 EEPROM (32 Kbit / 4 KB) accessible over I2C for configuration and data logging
• Works with 3.3 V and 5 V logic systems (ideal for Arduino, Raspberry Pi, ESP32, ESP8266, STM32)
• Two alarms, square-wave output (1 Hz to 8.192 kHz), and 32 kHz reference output
• Onboard temperature sensor for automatic drift compensation
• Backup battery holder for CR2032/LIR2032 coin cells

⚙️ Key Differences: DS3231 vs DS1307

The major advantage of the DS3231 over the DS1307 is its built-in temperature-compensated crystal. This TCXO significantly improves accuracy, typically to ±2 ppm (0°C to +40°C) and about ±3.5 ppm (-40°C to +85°C), translating to only a few seconds drift per month—ideal for precision timing in electronics modules and microcontroller applications.

🔌 Interface & Compatibility

• I2C interface (up to 400 kHz): easy integration with Arduino Wire library and Raspberry Pi SMBus
• Typical I2C addresses: 0x68 (DS3231 RTC) and 0x57 (24C32 EEPROM)
• Compatible with Arduino, Raspberry Pi, ESP32/ESP8266, STM32, and other electronics components platforms

📐 Pins (typical)

• VCC — 3.3 V to 5 V supply
• GND — Ground
• SDA — I2C data
• SCL — I2C clock
• SQW — Programmable square-wave / alarm interrupt output
• 32K — 32.768 kHz reference output

📊 Specifications

• RTC IC: DS3231 (TCXO-integrated)
• EEPROM IC: 24C32, 32 Kbit (4 KB)
• Logic level: 3.3 V or 5 V compatible
• Accuracy: ±2 ppm (0°C to +40°C), ±3.5 ppm (-40°C to +85°C) typical
• Communication: I2C/TWI, up to 400 kHz
• Outputs: SQW (1 Hz, 1.024 kHz, 4.096 kHz, 8.192 kHz), 32 kHz reference
• Backup battery: 20 mm coin cell holder (CR2032 or LIR2032)

⚠️ Important Battery Information

This board charges the coin cell from VCC via an onboard charging path. If you plan to use a non-rechargeable CR2032, you must modify the board to disable charging. Specifically, remove the charging resistor or zener/diode indicated on the PCB (often highlighted in yellow in guides). Using a CR2032 without this modification can be unsafe.
For hassle-free operation, use a rechargeable LIR2032 coin cell—no modification required.

🧪 Typical Applications

• Data loggers and timestamped measurements
• Low-power timekeeping for Arduino and Raspberry Pi projects
• Event scheduling, alarms, and periodic interrupts in microcontroller systems
• Frequency reference (32 kHz) and electronics modules testing

🚚 Shipping Information

Please note: Battery is not included with this product.