The DS3231 is a low-cost, high-precision I2C real-time clock (RTC) with an integrated temperature-compensated crystal oscillator (TCXO) and crystal. The device includes a battery input to maintain timekeeping when main power is removed. Integrated crystals improve accuracy and reduce component count in production.The DS3231 is available in commercial and industrial temperature ranges and comes in a 16-pin, 300-mil SO package. It stores seconds, minutes, hours, day of the week, date, month, and year. Months with fewer than 31 days are automatically adjusted, including leap year corrections.The clock supports both 24-hour and 12-hour formats with AM/PM indication. It features two programmable calendar alarms and a programmable square-wave output. Address and data are transmitted serially via the I2C bidirectional bus. A temperature-compensated voltage reference and comparator monitor VCC status, detect power supply failures, provide a reset output, and automatically switch to backup power when necessary.The RST pin can be used as a manual input to generate a microprocessor reset. In addition to high timing accuracy, the DS3231 includes an integrated digital temperature sensor accessible via the I2C interface (in addition to time data). The temperature sensor accuracy is ±3°C.On-chip control circuitry enables automatic power supply detection and manages switching between primary and backup power (e.g., low-voltage battery). If main power is lost, the device continues to provide accurate time and temperature readings without performance degradation. An on-chip reset function restarts the system microprocessor when main power is restored or voltage returns to the acceptable range.Key Features: 1. Compatible with other I2C devices; address configurable via A0/A1/A2 pins (default address: 0x57). 2. Requires CR2032 battery to maintain time during power loss. 3. Operating voltage: 3.3–5.5 V. 4. High-precision RTC chip: DS3231. 5. Clock accuracy: ±2 ppm within 0–40°C, resulting in approximately 1 minute annual error. 6. Calendar alarm function included. 7. Programmable square-wave output. 8. Tracks seconds, minutes, hours, day of week, date, month, and year with leap-year compensation valid until 2100. 9. Integrated temperature sensor with ±3°C accuracy. 10. Includes AT24C32 EEPROM (32 KB storage). 11. I2C interface with up to 400 kHz transmission speed (at 5 V).Wiring Example (for Arduino Uno R3): SCL → A5 SDA → A4 VCC → 5 V GND → GND Note: Minor variations in appearance, color, or silkscreen may occur between batches but do not affect functionality. Color: As shown in image. Material: PCB. Package Includes: 1 × DS3231 module Note: Lighting conditions and display settings may cause slight color differences between images and actual product. Measurement tolerance: ±1–3 cm.