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Adafruit PiRTC - Precise DS3231 Real Time Clock for Raspberry Pi

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DS3231-based RTC HAT for Raspberry Pi with coin cell battery backup and I2C interface. The DS3231 has a temperature-compensated crystal oscillator (TCXO) rated ±2ppm from 0–40°C, making it significantly more accurate than PCF8523-based alternatives.

Pinout

Logical pinout · physical placement not verified
ADAFRUIT PIRTC - PRECI3V3GND5VSQWSDA32K5VVBATSCLGND
  • 3V3Raspberry Pi 2x3 header pin 1

    Pi 3.3V rail for DS3231 supply

    Type · PowerVoltage · 3.3V
  • 5VRaspberry Pi 2x3 header pin 2

    Pi 5V pass-through rail

    Type · PowerVoltage · 5V
  • SDARaspberry Pi 2x3 header pin 3

    I2C data

    Type · I2CVoltage · 3.3V logic
  • 5VRaspberry Pi 2x3 header pin 4

    Pi 5V pass-through rail

    Type · PowerVoltage · 5V
  • SCLRaspberry Pi 2x3 header pin 5

    I2C clock

    Type · I2CVoltage · 3.3V logic
  • GNDRaspberry Pi 2x3 header pin 6

    Ground

    Type · GroundVoltage · 0V
  • SQWJP1 pad 1

    DS3231 square-wave/interrupt output pad

    Type · SignalVoltage · 3.3V logic
  • 32KJP1 pad 2

    DS3231 32 kHz output pad

    Type · SignalVoltage · 3.3V logic
  • VBATCR1220 holder positive terminal

    Backup battery positive for DS3231 VBAT

    Type · PowerVoltage · 3V coin cell
  • GNDCR1220 holder negative terminal

    Backup battery negative / ground

    Type · GroundVoltage · 0V

RTC & timing

26 other options

DS3231/DS3232 temperature-compensated RTCs, the budget PCF8523 and DS1307, the Si5351A clock generator (8kHz–160MHz), and bare 16MHz crystals — matched to drift tolerance and supply voltage.

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