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https://github.com/adafruit/adafruit_circuitpython_ds3231

Adafruit CircuitPython drivers for the DS3231 realtime clock.
https://github.com/adafruit/adafruit_circuitpython_ds3231

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Adafruit CircuitPython drivers for the DS3231 realtime clock.

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README 

        
Introduction

=============



.. image:: https://readthedocs.org/projects/adafruit-micropython-ds3231/badge/?version=latest

    :target: https://docs.circuitpython.org/projects/ds3231/en/latest/

    :alt: Documentation Status



.. image:: https://raw.githubusercontent.com/adafruit/Adafruit_CircuitPython_Bundle/main/badges/adafruit_discord.svg

    :target: https://adafru.it/discord

    :alt: Discord



.. image:: https://github.com/adafruit/Adafruit_CircuitPython_DS3231/workflows/Build%20CI/badge.svg

    :target: https://github.com/adafruit/Adafruit_CircuitPython_DS3231/actions/

    :alt: Build Status



.. image:: https://img.shields.io/badge/code%20style-black-000000.svg

    :target: https://github.com/psf/black

    :alt: Code Style: Black



The datasheet for the DS3231 explains that this part is an

"Extremely Accurate I²C-Integrated RTC/TCXO/Crystal". And,

hey, it does exactly what it says on the tin! This Real Time

Clock (RTC) is the most precise you can get in a small, low

power package.



Most RTCs use an external 32kHz timing crystal that is used

to keep time with low current draw. And that's all well and

good, but those crystals have slight drift, particularly when

the temperature changes (the temperature changes the oscillation

frequency very very very slightly but it does add up!) This

RTC is in a beefy package because the crystal is inside the

chip! And right next to the integrated crystal is a temperature

sensor. That sensor compensates for the frequency changes by

adding or removing clock ticks so that the timekeeping stays

on schedule.



This is the finest RTC you can get, and now we have it in a

compact, breadboard-friendly breakout. With a coin cell

plugged into the back, you can get years of precision

timekeeping, even when main power is lost. Great for

datalogging and clocks, or anything where you need to

really know the time.



.. image:: ../docs/_static/3013-01.jpg

    :alt: DS3231 Product Image



Dependencies

=============

This driver depends on:



* `Adafruit CircuitPython `_

* `Bus Device `_

* `Register `_



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:



.. code-block:: shell



    pip3 install adafruit-circuitpython-ds3231



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



.. code-block:: shell



    sudo pip3 install adafruit-circuitpython-ds3231



To install in a virtual environment in your current project:



.. code-block:: shell



    mkdir project-name && cd project-name

    python3 -m venv .venv

    source .venv/bin/activate

    pip3 install adafruit-circuitpython-ds3231



Usage Notes

===========



Basics

------



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



.. code:: python3



    import adafruit_ds3231

    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:



.. code:: python3



    import board



Now, to initialize the I2C bus:



.. code:: python3



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



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

the RTC object:



.. code:: python3



    rtc = adafruit_ds3231.DS3231(i2c)



Date and time

-------------



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



.. code:: python3



    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``.



.. code:: python3



    t = rtc.datetime

    print(t)

    print(t.tm_hour, t.tm_min)



Alarm

-----



To set the time, you need to set ``alarm1`` or ``alarm2`` to a tuple with a

``time.struct_time`` object and string representing the frequency such as "hourly":



.. code:: python3



    rtc.alarm1 = (time.struct_time((2017,1,9,15,6,0,0,9,-1)), "daily")



After the RTC is set, you retrieve the alarm status by reading the corresponding

``alarm1_status`` or ``alarm2_status`` attributes. Once True, set it back to False

to reset.



.. code:: python3



    if rtc.alarm1_status:

        print("wake up!")

        rtc.alarm1_status = False



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.