DS1307 Real Time Clock RTC Module

The DS1307 RTC Module is a reliable real-time clock module designed to provide accurate and continuous timekeeping for Arduino, ESP32, Raspberry Pi, STM32, and other embedded systems. It keeps track of seconds, minutes, hours, day, date, month, and year, making it suitable for applications that require precise time and date information.

The module communicates with a host microcontroller through the I²C two-wire serial interface, which simplifies connection and requires only a small number of communication pins. The DS1307 automatically handles month-end dates and leap-year adjustments, allowing the system to maintain the correct calendar information without requiring complex time-management code.

An onboard AT24C32 EEPROM provides 32Kbit (4KB) of non-volatile storage, allowing users to store configuration values, event information, settings, counters, or other small amounts of data that need to remain available even after the main power supply is removed.

The module includes a CR2032 coin-cell battery holder for backup timekeeping. When a suitable CR2032 battery is installed, the RTC can continue maintaining the time when the main system power is disconnected. The battery is not included with the module.

The DS1307 module also provides a 1Hz output signal, which can be used for timing and pulse-generation applications. Its compact design makes it suitable for embedded systems, data loggers, clocks, automation projects, IoT devices, and educational electronics applications.

Features

• Real-time clock module based on the DS1307 IC
• Tracks seconds, minutes, hours, day, date, month, and year
• Automatic leap-year adjustment
• Automatic month-end date adjustment
• I²C two-wire serial communication interface
• Compatible with Arduino, ESP32, ESP8266, Raspberry Pi, STM32, AVR, PIC, and other suitable controllers
• Onboard AT24C32 32Kbit (4KB) EEPROM
• Provides non-volatile memory for data storage
• CR2032 backup battery holder
• Maintains time during main power interruption when a battery is installed
• 1Hz square-wave output
• Low power consumption
• Compact module design
• Suitable for time-stamping applications
• Useful for data logging and automation
• Suitable for IoT and embedded systems
• Easy to integrate into microcontroller projects

Specifications

Parameter	Specification
Product Type	Real Time Clock Module
RTC IC	DS1307
Communication Interface	I²C / Two-Wire Serial
Backup Battery	CR2032 Coin Cell
Battery Included	No
EEPROM IC	AT24C32
EEPROM Capacity	32Kbit / 4KB
RTC User Memory	56 Bytes
Output Signal	1Hz Square Wave
Operating Voltage	3.3V–5V
Dimensions	Approximately 27mm × 28mm × 8.4mm
Operating Temperature	0°C to +70°C
Compatible Platforms	Arduino, ESP32, ESP8266, Raspberry Pi, STM32, AVR, PIC
Application	Timekeeping, Data Logging, Automation & IoT

Design and Construction

The DS1307 RTC module is built around the DS1307 real-time clock IC and includes the supporting circuitry required for timekeeping and microcontroller communication. Its compact PCB design makes it convenient to integrate into breadboard prototypes, embedded systems, control panels, and custom electronic devices.

The module includes an onboard CR2032 battery holder, allowing a backup coin-cell battery to be installed so that the RTC can continue maintaining time when the primary system power is disconnected. The CR2032 battery itself is not included.

An AT24C32 EEPROM is also provided on the module, offering additional non-volatile storage for project data. Information stored in the EEPROM can remain available even after the main power supply is removed.

The module provides an I²C interface for communication with the host microcontroller. This two-wire interface simplifies wiring and allows the RTC and EEPROM to be accessed from compatible microcontroller platforms.

The board also provides a 1Hz output signal, which can be used by external circuitry or a microcontroller for timing-related applications.

DS1307 RTC Module reference image

Working Principle

The DS1307 maintains the current time and calendar information using its internal real-time clock circuitry. It continuously keeps track of seconds, minutes, hours, day, date, month, and year.

The connected microcontroller communicates with the RTC through the I²C interface to read the current time and date or update the clock settings. The microcontroller can use this information to perform time-based operations, display the current time, or add timestamps to stored data.

When the main power supply is available, the module operates from the system power. When the main power is removed and a suitable CR2032 backup battery is installed, the RTC can continue maintaining the time.

The DS1307 automatically handles calendar functions such as month-end date changes and leap-year adjustments, reducing the amount of calendar-processing work required from the microcontroller.

The onboard AT24C32 EEPROM operates as additional non-volatile memory. The microcontroller can use it to store small amounts of information such as configuration settings, event records, counters, or other data that should remain stored after power loss.

The 1Hz output pin generates a square-wave timing signal that can be used for timing, synchronization, or pulse-generation applications.

Applications

• Real-time clock systems
• Arduino clock projects
• Digital clock projects
• Time and date display systems
• Time-stamped data logging
• Environmental data loggers
• IoT devices
• Time-based automation systems
• Alarm clock projects
• Event scheduling systems
• Access control systems
• Attendance systems
• Industrial automation
• Embedded control systems
• Smart home projects
• Energy monitoring systems
• Temperature data logging
• Sensor data logging
• Electronic timers
• Calendar-based automation
• Microcontroller projects
• Educational electronics projects
• Raspberry Pi timekeeping projects
• ESP32 and ESP8266 IoT projects
• Battery-backed timekeeping applications

Package Includes

• 1 × DS1307 RTC Module with CR2032 Battery Holder

Note: CR2032 backup battery is not included.

Product Disclaimer

Product images are shown for illustrative and representational purposes only. The actual product may vary slightly in colour, dimensions, PCB layout, component placement, connector arrangement, or appearance depending on the manufacturing batch.

CR2032 battery, Arduino boards, ESP32 boards, Raspberry Pi boards, connecting wires, breadboards, displays, sensors, power supplies, and other components shown in product images are not included unless specifically mentioned in the package contents.

The backup battery is not included. Install a suitable CR2032 coin-cell battery in the holder if backup timekeeping is required.

Timekeeping accuracy can vary depending on the RTC characteristics, ambient temperature, battery condition, power supply, and operating environment.

The module should be operated within its specified voltage and temperature ranges. Verify the wiring and I²C connections before powering the module.

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