DS3231 rtc module

DS3231 RTC Module

DS3231 RTC Module (Real Time Clock Module) is used to track the current time and date and generally used in computers, laptops, mobiles, embedded system applications devices, etc.

It is also called the Real-Time Clock Module which is a low-cost, extremely accurate I²C RTC with a battery(Cell) and an integrated temperature-compensated crystal oscillator (TCXO) and crystal.

The built-in power-sense circuit continuously monitors the status of VCC to detect power failures and automatically switches to the backup supply. So, you need not worry about power outages, your MCU can still keep track of time.

The clock operates in both time format i.e. 24 hours and 12 hours with an AM/PM indicator.

There are different types of ICs used for RTC like DS1307, DS12C887, etc.

DS3231 RTC Module

DS3231 RTC Module Pinout

DS3231 Pinout

  • VCC:- For giving power supply to module this pin is used and connected to 3.3V or 5V pin of Arduino.
  • GND:- It is ground pin and connects to Arduino ground pin.
  • SDA and SCL:- These are Serial Data pin and Serial clock pin which is used in I2C serial communicaton and connects with microcontroller's I2C pins.
  • SQW:- This is Square Wave pin is driven at either 1Hz, 4kHz, 8kHz or 32kHz and handled programmatically.
  • 32K:- The RTC DS3231 uses external crystal of frequency 32 kHz which gives output stable and accurate reference clock.


I2C interface Fast (400kHz) I2C Interface
EEPROM AT24C32 32Kbit Serial I2C
Digital Temp Sensor Output 10 bit, ±3°C Accuracy and 0.25C resolution
Time Format HH: MM: SS (12/24 hr)
Date Format YY-MM-DD-dd
Accuracy ±2ppm from 0°C to +40°C
Accuracy ±3.5ppm from -40°C to +85°C
1Hz output pin SQW
32KHz output pin 32K
Voltage Supply 2.2 V ~ 5.5 V (for RTC)
Operating Voltage (VCC) 2.7V ~ 5.5V (including 24C32)
Operating Temperature Ranges Commercial (0°C to +70°C) and Industrial (-40°C to +85°C)
Battery Holder 2032 Coin Battery
Size 38 (L) x 22 (W) x 14 mm (H)
Weight 8 gm (including Battery)


  • DS3231 RTC module had a 2032 Battery Holder.
  • This RTC module counts time in seconds,minutes,hours dste of month, month, day of week and year with leap year (valid up to 2100).
  • We Programmed two time-of-day alarms.
  • Programmable Square-Wave Output Signal.
  • Had Battery backup for continuous timekeeping.
  • Use Low Power Operation which extends Battery run time.

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