Note the EEPROM can be left out.

DS1307 Real Time Clock Raspberry Pi I2C Interface

by Lewis Loflin

Note one can use any pre-made module.

Updated latest Raspbian 2019.

First let's do an update of the system if you haven't already:

~ $ sudo apt-get update && sudo apt-get upgrade

Some of these may already be installed:

~ $ sudo apt-get install i2c-tools python-smbus

Stop! If running latest Rasbian with i2c enabled the DS1307 works by default.

Setting the RTC Clock

The RTC module must be loaded by the kernel by running:

~ $ sudo modprobe rtc-ds1307

Now you need to be running as the super user; type in:

~ $ sudo bash

Then, if you have a Rev.2 Raspberry Pi or later:

~ $ echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device

Or if you have the older Rev.1 Raspberry Pi, use:

~ $ echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-0/new_device

Then:

~ $ sudo geany /boot/config.txt

Add:

# hardware clock

device_tree=bcm2710-rpi-3-b.dtb

dtparam=i2c_arm=on

dtoverlay=12c-rtc,ds1307

Assuming leafpad is your text editor (if not use geany) we need to have the i2c modules loaded by default at boot time so add the following to /etc/modules opened in a text editor:

~ $ sudo leafpad /etc/modules

Add if not already there:

i2c-dev

i2c-bcm2708

rtc-ds1307

Save and then exit the editor.

Rebbot Raspberry Pi.

Next you will need to add the DS1307 device creation at boot by editing the /etc/rc.local file by running

~ $ sudo leafpad /etc/rc.local

Add the following lines to the file: before exit:

echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device

sudo hwclock -s

date

Then reboot.

In terminal type sudo i2cdetect -y 1 (enter) and you should see:

This if the DS1307 is recognized:

pi@raspberrypi:~ $ sudo i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --

68 is now UU.

Now let's set the time

pi@raspberrypi:~ $ date

Sun Feb 10 13:50:51 EST 2019

Use your current time and date!

If not correct set the time-date. Change time-date in Linux command line:

~ $ date -s "28 APR 2019 10:42:00"

To update the RTC:

~ $ sudo hwclock -w

Check the DS1307 RTC:

~ $ pi@raspberrypi:~ $ sudo hwclock -r

To allow a user such as pi to access i2c from userspace if needed:

~ $ sudo adduser $USER i2c

Reboot and ready to go.

This is a collection of programs and hardware hacks related to mainly Raspberry Pi and Debian Linux.