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DS1307
MicroPython driver for the DS1307 real time clock
This module provides a MicroPython driver for the DS1307 real time clock.
Acknowledgement: This module was derived in outline from the Adafruit circuit python DS1307 real time clock library. That library was authored by Philip R. Moyer and Radomir Dopieralski for Adafruit Industries. See repository: Adafruit_CircuitPython_DS1307.
Beware the DS1307 breakout works at 5V but many micro-controller and computer boards have a 3.3v logic level. Make sure that the SCL and SDA pins on the board used are 5v tolerant or level shifted to 3.3v!
The accompanying example code uses the SoftI2C class. With the Raspberry Pi Pico, using the SoftI2C class instead of the hardware I2C class can avoid EIO errors that may be otherwise experienced, perhaps due to I2C clock stretching (see: RP2: Hard I2C is intolerant of clock stretching).
Version
This is a production version (v104).
Usage
Here is an example of using the DS1307 class.
First you will need to import the MicroPython Pin and SoftI2C modules to use the sensor
from machine import Pin, SoftI2C
import ds1307
Once this is done you can construct a SoftI2C object and a ds1307.DS1307 object
# uses SoftI2C class and pins for Raspberry Pi pico
i2c0 = SoftI2C(scl=Pin(1), sda=Pin(0), freq=100000)
ds1307rtc = ds1307.DS1307(i2c0, 0x68)
Now you can give the current time to the DS1307 device using the class' datetime property. This takes a 7-tuple consisting of the year (4-digit format), month, day, hour (24-hour clock), minutes, seconds, weekday (in the range 0-6). Setting the time with this property also enables the clock's oscilator. The base for the weekday (that is zero) can be choosen according to user preferences. (The MicroPython port for the Pi pico sets Monday to zero for the pico internal RTC so Monday=0 may be a good choice for consistency.)
# set time (year, month, day, hours. minutes, seconds, weekday: integer: 0-6 )
ds1307rtc.datetime = (2022, 12, 18, 18, 9, 17, 6)
You can access the current time from the DS1307 using the datetime property. This property returns the date, time and weekday as a 7-tuple as follows: 4-digit year, month, day, hour (24-hour clock), minutes, seconds, weekday (in the range 0-6).
current_time = ds1307rtc.datetime
The datetimeRTC property returns the current time from the DS1307 in a format suitable for setting the Pico's internal real time clock. This is as an 8-tuple with the date as the first three elements followed by a None value, then the time and finally another None value. In order to set the Pico's clock the machine.RTC class must be imported.
from machine import RTC
machine.RTC().datetime(ds1307rtc.datetimeRTC)
Finally, the disable oscillator property may be useful to stop the clock when not in use and reduce demand on the standby battery.
See also the example code provided in this repository.
Features
The current time is set and access by means of properties. A 12 hour am/pm time stored in the DS1307 will be read as a 24 hour clock time. The time can only be set using 24-hour clock format
Interfaces and tested devices
The code uses the I2C interface of the DS1307.
This driver has been tested with a Raspberry Pi Pico and an Adafruit DS1307 breakout. As the DS1307 works at 5V and the Pico uses 3.3V logic, an I2C-compatible level shifter breakout was also used.
Requirements
This code has been tested with MicroPython version 1.19.1.
Datasheet
DS1307.pdf at Analog industries
Release notes
Version 104
Initial version