DS3231 RTC real-time clock for Raspberry Pi, integrated battery

Product detailed description

The DS3231 RTC module with an integrated backup battery is a precise I2C real-time clock module that mounts directly onto the Raspberry Pi GPIO connector and maintains time even during power failures. The DS3231 circuit features a 32.768 kHz temperature-compensated crystal oscillator (TCXO), ensuring that the clock remains highly accurate with minimal drift during temperature fluctuations. The module tracks seconds, minutes, hours, day of the week, and date including leap years, offers two programmable alarms, and includes a built-in temperature sensor. Thanks to 3.3 V and 5 V power supply compatibility, you can use it with Arduino, ESP32, and other boards.

Specifications:

• Chip: DS3231 (clone)
• Interface: I2C, up to 400 kHz, address 0x68, pull-up resistors mounted on the module
• Power supply: 3.3 V or 5 V DC (chip range 2.3–5.5 V)
• Oscillator: 32.768 kHz temperature-compensated (TCXO)
  • Accuracy: ±2 ppm in the range 0 to +40 °C (approx. ±2 min/year) according to the DS3231 datasheet
• Function:
  • seconds, minutes, hours, day of the week, date, month, year (up to the year 2100, including leap years)
  • 12h / 24h format
  • 2 programmable alarms (readable via I2C, SQW/INT output is not routed)
• Temperature sensor: 0.25 °C resolution, ±3 °C accuracy
• Backup battery: 3 V CR927 lithium coin cell with solder pins, non-rechargeable, pre-installed on the module
• Pins: 5-pin female header with 2.54 mm pitch
  • + – VCC power supply
  • D – SDA
  • C – SCL
  • NC – not connected
  • − – GND
• Compatibility: Raspberry Pi (fits pins 1, 3, 5, 7, 9 of the GPIO connector), Arduino, ESP32, ESP8266 and other I2C boards; recommended library for Arduino is RTClib (Adafruit)
• Dimensions: 14 × 13.5 × 12.6 mm
• Weight: approx. 4 g
• Other RTC modules available:
  • LaskaKit DS3231 orig. RTC hodiny reálného času – originální čip DS3231
  • DS3231 AT24C32 RTC real-time clock – with a replaceable battery holder and EEPROM memory

Important wiring notice:

• On a Raspberry Pi, fit the module onto pins 1–9 of the GPIO connector so that the + pin is on pin 1 (3.3 V). No additional driver is required: enable I2C in Raspberry Pi OS and add the line dtoverlay=i2c-rtc,ds3231 to the config.txt file.
• The I2C bus pull-up resistors are connected to the module's power supply. Therefore, power the module from 3.3 V when using boards with 3.3 V logic (Raspberry Pi, ESP32). With a 5V Arduino, you can use 5 V, ensuring the module runs reliably over the long term.
• The battery is non-rechargeable and will not be charged by connecting the power supply. When the module is not powered, the battery maintains the clock operation. When stored for a long time without power, it will last approximately 1–3 years before the battery drains.
• After the first connection or once the battery is depleted, you must reset the time (e.g., using the rtc.adjust() function in the RTClib library). Until the time is set, the module may return zero or invalid values.
• If you require a longer battery life or wish to replace the battery, you can solder an external CR2032 battery holder instead of the integrated cell. Alternatively, choose the DS3231 AT24C32 module with a battery holder.

Package contents:

• 1× DS3231 RTC module with installed CR927 battery

Important Notice and Safety:

• The battery on the module is non-rechargeable – do not attempt to charge it.
• Keep the module out of reach of children – button cell batteries are life-threatening if swallowed.
• Do not short-circuit the battery terminals and do not expose the module to high temperatures, fire, or moisture.
• Dispose of depleted batteries or the entire module at a battery or electronic waste collection point.

Note:

• This product is not a standalone functional unit and may require professional installation.
• Product images are for illustrative purposes only and may sometimes differ from the actual appearance of the item. However, this does not change their basic properties.