Introduction

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This is a great 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. Perfect for datalogging, clock-building, time stamping, timers and alarms, etc. The DS1307 is the most popular RTC - but it requires 5V power to work.

The DS1307 is simple and inexpensive but not a high precision device. It may lose or gain up to two seconds a day. For a high-precision, temperature compensated alternative, please check out the DS3231 precision RTC. If you do not need a DS1307, or you need a 3.3V-power/logic capable RTC please check out our affordable PCF8523 RTC breakout.

DS1307

Dependencies

This driver depends on:

Please ensure all dependencies are available on the CircuitPython filesystem. This is easily achieved by downloading the Adafruit library and driver bundle.

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 adafruit-circuitpython-ds1307

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

sudo pip3 install adafruit-circuitpython-ds1307

To install in a virtual environment in your current project:

mkdir project-name && cd project-name
python3 -m venv .env
source .env/bin/activate
pip3 install adafruit-circuitpython-ds1307

Usage Notes

Of course, you must import the library to use it:

import board
import adafruit_ds1307
import time

All the Adafruit RTC libraries take an instantiated and active I2C object (from the board library) as an argument to their constructor. The way to create an I2C object depends on the board you are using. For boards with labeled SCL and SDA pins, you can:

import board

Now, to initialize the I2C bus:

i2c = board.I2C()

Once you have created the I2C interface object, you can use it to instantiate the RTC object:

rtc = adafruit_ds1307.DS1307(i2c)

To set the time, you need to set datetime to a time.struct_time object:

rtc.datetime = time.struct_time((2017,1,9,15,6,0,0,9,-1))

After the RTC is set, you retrieve the time by reading the datetime attribute and access the standard attributes of a struct_time such as tm_year, tm_hour and tm_min.

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

Contributing

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

Documentation

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

Table of Contents

Simple test

Ensure your device works with this simple test.

examples/ds1307_simpletest.py
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# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT

# Simple demo of reading and writing the time for the DS1307 real-time clock.
# Change the if False to if True below to set the time, otherwise it will just
# print the current date and time every second.  Notice also comments to adjust
# for working with hardware vs. software I2C.

import time
import board
import adafruit_ds1307

i2c = board.I2C()
rtc = adafruit_ds1307.DS1307(i2c)

# Lookup table for names of days (nicer printing).
days = ("Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday")


# pylint: disable-msg=using-constant-test
if False:  # change to True if you want to set the time!
    #                     year, mon, date, hour, min, sec, wday, yday, isdst
    t = time.struct_time((2017, 10, 29, 15, 14, 15, 0, -1, -1))
    # you must set year, mon, date, hour, min, sec and weekday
    # yearday is not supported, isdst can be set but we don't do anything with it at this time
    print("Setting time to:", t)  # uncomment for debugging
    rtc.datetime = t
    print()
# pylint: enable-msg=using-constant-test

# Main loop:
while True:
    t = rtc.datetime
    # print(t)     # uncomment for debugging
    print(
        "The date is {} {}/{}/{}".format(
            days[int(t.tm_wday)], t.tm_mday, t.tm_mon, t.tm_year
        )
    )
    print("The time is {}:{:02}:{:02}".format(t.tm_hour, t.tm_min, t.tm_sec))
    time.sleep(1)  # wait a second

adafruit_ds1307 - DS1307 Real Time Clock module

CircuitPython library to support DS1307 Real Time Clock (RTC).

This library supports the use of the DS1307-based RTC in CircuitPython.

Beware that most CircuitPython compatible hardware are 3.3v logic level! Make sure that the input pin is 5v tolerant.

  • Author(s): Philip R. Moyer and Radomir Dopieralski for Adafruit Industries

Implementation Notes

Hardware:

Software and Dependencies:

Notes:

  1. Milliseconds are not supported by this RTC.
  2. Alarms and timers are not supported by this RTC.
  3. Datasheet: https://datasheets.maximintegrated.com/en/ds/DS1307.pdf
class adafruit_ds1307.DS1307(i2c_bus)[source]

Interface to the DS1307 RTC.

Parameters:i2c_bus (I2C) – The I2C bus the device is connected to

Quickstart: Importing and using the device

Here is an example of using the DS1307 class. First you will need to import the libraries to use the sensor

import time
import board
import adafruit_ds1307

Once this is done you can define your board.I2C object and define your sensor object

i2c = board.I2C()  # uses board.SCL and board.SDA
rtc = adafruit_ds1307.DS1307(i2c)

Now you can give the current time to the device.

t = time.struct_time((2017, 10, 29, 15, 14, 15, 0, -1, -1))
rtc.datetime = t

You can access the current time accessing the datetime attribute.

current_time = rtc.datetime
datetime

Gets the current date and time or sets the current date and time then starts the clock.

datetime_register

Current date and time.

disable_oscillator

True if the oscillator is disabled.

Indices and tables