DS1302 RTC Real Time Clock Module

DS1302 RTC Real Time Clock Module is a high-performance, low-power timekeeping device that maintains accurate time and date information for microcontrollers even when the main power supply fails. This module contains a real-time clock/calendar and 31 bytes of static RAM, communicating with a host processor via a simple three-wire serial interface. Consequently, it manages seconds, minutes, hours, day, date, month, and year information automatically, including adjustments for months with fewer than 31 days and leap year corrections. The module typically includes a battery holder for a CR2032 button cell. Therefore, the device continues to track time for years without external power, making it an indispensable component for data logging and scheduled automation.

Key Features:

• Complete Timekeeping: The DS1302 counts seconds, minutes, hours, date of the month, month, day of the week, and year with leap-year compensation valid up to the year 2100.
• Trickle-Charge Capability: It features a programmable trickle-charge circuit for the backup battery, which ensures the power source remains ready during outages.
• Three-Wire Serial Interface: The module utilizes a simple synchronous serial interface (SCLK, I/O, CE), requiring only three digital pins from the microcontroller.
• On-Board RAM: It provides 31 bytes of non-volatile data storage RAM for keeping small amounts of critical system parameters.
• Wide Voltage Range: The module operates reliably on a wide range of supply voltages, which simplifies integration into both 3.3V and 5V logic systems.

Technical Specifications:

• Operating Voltage (VCC): 2.0 V to 5.5 V
• Backup Battery Voltage: 2.0 V to 5.0 V (Typically CR2032)
• Current Consumption: Less than 300 nA at 2.0 V (Typical power-down mode)
• Interface Type: 3-Wire Serial (Synchronous)
• Clock Accuracy: Determined by external 32.768 kHz crystal (included on module)
• Data Storage: 31 Bytes of scratchpad RAM
• Temperature Range: 0°C to +70°C (Commercial Grade)

Mechanical Specifications:

• Board Material: High-quality FR4 PCB
• Mounting: 4 x 3.1 mm mounting holes for secure installation
• Crystal Type: Integrated 32.768 kHz cylindrical crystal
• Battery Holder: Integrated coin-cell holder (compatible with CR2032)

Dimensions:

• PCB Length: ≈ 44 mm
• PCB Width: ≈ 23 mm
• Overall Height: ≈ 11 mm (including battery holder)
• Weight: ≈ 8 g (without battery)

Pinout and Wiring:

• VCC: Connect to the positive power supply (3.3 V or 5 V).
• GND: Connect to the common ground of your circuit.
• CLK (SCLK): Serial Clock input, used to synchronize data movement on the serial interface.
• DAT (I/O): Bi-directional data pin for transferring time and RAM data.
• RST (CE): Reset/Chip Enable. Drive this pin high to initiate a data transfer.
• Wiring Tip: Furthermore, ensure you use a common ground between the module and the microcontroller to prevent communication errors.

Datasheet Reference:

• Download Maxim Integrated DS1302 Datasheet

Commonly Used in:

• Development Platforms: Widely used with Arduino, ESP8266, and Raspberry Pi projects for time-stamping data.
• Consumer Electronics: Found in digital clocks, kitchen appliances, and thermostats.
• Educational Kits: A staple in STEM kits for teaching serial communication and timekeeping logic.

Applications:

• Data Logging: Recording sensor readings with precise timestamps for environmental monitoring.
• Scheduled Tasks: Controlling relays or motors at specific times of the day (e.g., automated plant watering).
• Attendance Systems: Tracking entry and exit times in DIY security or logging systems.
• User Interfaces: Displaying the current time and date on LCD or OLED screens.

Equivalent Models:

• DS1307: A popular alternative that uses the I2C protocol instead of the 3-wire interface.
• DS3231: A high-precision RTC with an integrated temperature-compensated crystal oscillator.
• PCF8563: A low-power CMOS real-time clock/calendar primarily used in mobile applications.

Package Includes:

• 1 x DS1302 RTC Real Time Clock Module (Battery not included)