# Precision RTC Module, DS1307, I2C, 3.3-5V

> DS1307 RTC module with I2C interface for precise time and date measurement (hours, minutes, seconds, day, month, year). Power supply 3.3-5.5 VDC, AT24C32 memory chip (32 KB EEPROM), SQ output for square wave signal, 1 Hz update frequency, accurate calendar up to 2100. Supports CR2032 or LIR2032 backup battery (not included). Board dimensions 28 x 28 mm. Compatible with Arduino and other development boards.

- Page: https://sigmanortec.ro/en/precision-rtc-module-ds1307-i2c-33-5v
- Price: 4.99 RON
- Availability: In stock; 1-2 zile
- Reference: 33042 · EAN: 5944168863785
- Category: Mechatronics and IoT > Sensors and Modules > Clock Module
- Specifications: tension: AD; Supply Voltage: 3.3; Maximum Input Voltage: 5
- Package (shipping data): 0.004 kg
- Updated: 2026-09-14
- Shop: [Sigmanortec.ro](https://sigmanortec.ro/en/llms.txt)
- Prices: RON, VAT included; prices and stock as of 2026-10-22 03:25 (Europe/Bucharest)

## Description

The DS1307 RTC module provides accurate time and date measurement for Arduino and other boards, with easy-to-integrate I2C communication. It operates at 3.3-5V and keeps time with a CR2032 backup battery, includes an AT24C32 EEPROM for additional storage, and a SQ output for square wave signal, ideal for automation, monitoring, and IoT projects.
The Real Time Clock RTC DS1307 module is a practical solution for Arduino projects and other development boards, providing precise time measurement and real-time calendar management. This module allows reading the time in hours, minutes, and seconds format, as well as the full date, including day, month, and year.
It integrates the DS1307 chip for the clock function and the AT24C32 memory, useful for storing additional data directly on the module. Communication is done through the I2C interface, which greatly simplifies connection and use in electronic applications, automation, monitoring systems, or IoT projects.
The module operates with a power supply between 3.3 and 5.5 VDC, being compatible with a wide range of development platforms. It includes support for a backup battery type CR2032 or LIR2032 (not included), so that time and date are preserved even in case of power interruption. The integrated calendar ensures correct long-term operation, and the 1 Hz update frequency provides stable and precise readings. Its compact dimensions make it easy to integrate into projects where available space is limited.
Specifications:
Power supply voltage: 3.3 - 5.5 VDC
Clock chip: DS1307
Memory chip: AT24C32
EEPROM memory capacity: 32 KB
Communication interface: I2C / IIC / TWI
Interface lines: SDA, SCL
Data update frequency: 1 Hz
Available data: hour, minute, second, day, month, year
Compatible backup battery: CR2032 or LIR2032 (not included)
Output signal: SQ for square wave
Accurate calendar: up to the year 2100
Board dimensions: 28 x 28 mm
Pinout:
Pin
Description
SQ
Square wave signal output
DS
Output for DS18B20 temperature sensor
SCL
Clock line for I2C interface
SDA
Data line for I2C interface
VCC
Module power supply 3.3 - 5.5 VDC
GND
System ground
BAT
Connection for backup battery
Usage:
Connect the VCC pin to the development board power source.
Connect the GND pin to the system ground.
Connect the SDA and SCL lines to the board's I2C interface.
The SQ pin can be used for square wave signal output, depending on configuration.
Install a compatible battery to keep time when the main power is off.
Time Setting:
For the initial setting of time and date, use the setRegister(...) lines in the setup() section.
The order of registers is as follows: setRegister(0, value) for seconds, setRegister(1, value) for minutes, setRegister(2, value) for hours, setRegister(3, value) for day of the week, setRegister(4, value) for day of the month, setRegister(5, value) for month, setRegister(6, value) for year.
Example for the date 17/03/2026 and time 14:30:00: setRegister(0, 0), setRegister(1, 30), setRegister(2, 14), setRegister(3, 2), setRegister(4, 17), setRegister(5, 3), setRegister(6, 26).
After uploading the code with the desired values, the setting lines should be commented out and the sketch should be re-uploaded to avoid rewriting the time at every restart.
The module will automatically keep the set time and date with the help of the backup battery, even in case of power interruption.
Day Numbering:
Value
Day
1
Monday
2
Tuesday
3
Wednesday
4
Thursday
5
Friday
6
Saturday
7
Sunday
Arduino Example:
Module Pin
Arduino Uno Pin
VCC
5V
GND
SDA
A4
SCL
A5
SQ
D2
Code available in the product's test section.