Adafruit DS3231 Precision RTC - STEMMA QT

The Adafruit DS3231 Precision RTC with STEMMA QT connectors is a highly accurate I2C real-time clock featuring an integrated temperature-compensated crystal oscillator (TCXO). Unlike standard RTCs that rely on an external 32 kHz crystal, the DS3231 houses the crystal internally alongside a temperature sensor that continuously compensates for frequency drift, delivering accuracy of ±2 ppm (about ±1 minute per year).

This version adds STEMMA QT / Qwiic connectors for solderless I2C connections, making it easy to daisy-chain with other I2C sensors and accessories. It works with both 3.3V (Feather, Raspberry Pi) and 5V (Arduino, Metro) logic levels. With a CR1220 coin cell on the back, the DS3231 maintains precise timekeeping for years even when main power is lost.

Key Features

• Integrated TCXO – On-chip crystal and temperature sensor for automatic drift compensation
• ±2 ppm Accuracy – Approximately ±1 minute per year, far superior to standard RTCs
• STEMMA QT / Qwiic – Dual I2C connectors for solderless daisy-chaining
• Battery Backup – CR1220 coin cell holder on board for uninterrupted timekeeping during power loss
• 3.3V and 5V Compatible – On-board level shifting for broad platform support
• I2C Interface – Simple two-wire communication with standard I2C addressing
• Breadboard-Friendly – Compact breakout with included header strip

Also Available

• DS3231 Precision RTC Breakout (standard header version)
• DS1307 RTC Breakout (basic, lower cost)
• PCF8523 RTC Breakout (3.3V compatible)

Ideal For

• Precision data logging with accurate timestamps
• Clocks and timers requiring minimal drift
• IoT devices needing reliable timekeeping through power cycles
• Solderless prototyping with STEMMA QT ecosystem

Package Contents

• 1× Adafruit DS3231 Precision RTC – STEMMA QT (fully assembled and tested)
• 1× Header strip