Introduction to the DS1302 Real Time Clock (RTC) Library

The DS1302 is a small battery-backed real time clock (RTC) that allows your microcontroller project to keep track of time even if it is reprogrammed, or if the power is lost. This is perfect for clocks, datalogging, timers, etc. The DS1302 also features a trickle charger for the battery so you never need to change batteries.

The DS1302 is simple and inexpensive but not a high precision device. It may lose or gain up to two seconds a day. In addition, it communicates over a custom serial protocol. For a high-precision, temperature compensated, alternative, please check out the DS3231 precision RTC, which communicates over I2C.

Dependencies

This driver depends on:

• Adafruit CircuitPython

Please ensure all dependencies are available on the CircuitPython filesystem. This is easily achieved by downloading the Adafruit library and driver bundle or individual libraries can be installed using circup.

Installing from PyPI

On supported GNU/Linux systems like the Raspberry Pi, you can install the driver locally from PyPI. To install for current user:

pip3 install circuitpython-ds1302

To install system-wide (this may be required in some cases):

sudo pip3 install circuitpython-ds1302

To install in a virtual environment in your current project:

mkdir project-name && cd project-name
python3 -m venv .venv
source .env/bin/activate
pip3 install circuitpython-ds1302

Installing to a Connected CircuitPython Device with Circup

Make sure that you have circup installed in your Python environment. Install it with the following command if necessary:

pip3 install circup

With circup installed and your CircuitPython device connected use the following command to install:

circup install ds1302

Or the following command to update an existing version:

circup update

Usage Example

import time
import board
import ds1302

import board
reset_pin = board.GP13
io_pin = board.GP14
clock_pin = board.GP15

rtc = ds1302.DS1302(reset_pin, io_pin, clock_pin)

rtc.datetime = time.struct_time((2026, 7, 16, 12, 38, 0, 3, -1, -1))

t = rtc.datetime
print(t)
print(t.tm_hour, t.tm_min)

Documentation

API documentation for this library can be found on Read the Docs.

For information on building library documentation, please check out this guide.

Contributing

Contributions are welcome! Please read our Code of Conduct before contributing to help this project stay welcoming.