This awesome little Real-Time clock module features a DS3231 I2C with Integrated temperature compensated RTC/Crystal - a low-cost, extremely accurate I2C real-time clock (RTC).

The module can - with the onboard battery holder - be powered CR2032 or an external power source.

The circuit maintains accurate timekeeping - even when the main power to the device is interrupted. The integration of the crystal resonator enhances the long-term accuracy of the device as well as reduces the piece-part count in a manufacturing line.

The RTC maintains seconds, minutes, hours, day, date, month, and year information. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including corrections for leap year.

The clock operates in either the 24-hour or 12-hour format with an AM/PM indicator. Two programmable time-of-day alarms and a programmable square-wave output are provided.

Address and data are transferred serially through an I2C bidirectional bus. A precision temperature-compensated voltage reference and comparator circuit monitors the status of VCC to detect power failures, to provide a reset output, and to automatically switch to the backup supply when necessary. Additionally, the RST pin is monitored as a pushbutton input for generating a μP reset.

FEATURES

• Highly Accurate RTC Completely Manages All Timekeeping Functions
• Real-Time Clock Counts Seconds, Minutes, Hours, Date of the Month, Month, Day of the Week, and Year, with Leap-Year Compensation Valid Up to 2100
• Accuracy ±2ppm from 0°C to +40°C
• Accuracy ±3.5ppm from -40°C to +85°C
• Digital Temp Sensor Output: ±3°C Accuracy
• Register for Aging Trim
• RST Output/Pushbutton Reset Debounce Input
• Two Time-of-Day Alarms
• Programmable Square-Wave Output Signal
• Temperature Compensated 32Khz crystal oscillator
• Simple Serial Interface Connects to Most Microcontrollers
• Fast (400kHz) I2C Interface
• Battery-Backup Input for Continuous Timekeeping
• Low Power Operation Extends Battery-Backup Run Time
• 3.3V Operation

On Board

• DS3231M chip
• Battery Holder
• DS3231M Chip breakout PINs for the 3-wire interface and additional  backup power