RTC Pi on a Raspberry Pi with Raspbian wheezy
Created 02/10/2015 | A tutorial showing how to use the RTC Pi on a Raspberry Pi.
This page details how to setup the RTC Pi on the Raspbian “wheezy” image from http://www.raspberrypi.org/downloads
Step 1: With your Raspberry Pi switched off install the RTC Pi on the Raspberry Pi GPIO port and insert a CR2032 coin battery into the battery holder. Using the RTC Pi without a battery installed may damage the RTC Pi and will stop it from appearing on the I2C bus.
Step 2: Follow the instructions on how to install and configure I2C on Raspbian Linux.
Step 3: Once you have installed I2C check that the RTC Pi has been detected using:
sudo i2cdetect -y 0 # (if using v1 Raspberry Pi or)
sudo i2cdetect -y 1 # (if using v2 Raspberry Pi)
The RTC Pi should appear on channel 68 as shown in the screen shot below. If the RTC Pi does not appear check that the battery is installed correctly and is fully charged:
Step 3: Enable I2C by running:
sudo nano /etc/modprobe.d/raspi-blacklist.conf
Find the I2C line where the I2c is black listed
blacklist i2c-bcm2708
Comment it out by replacing it with the line below
#blacklist i2c-bcm2708
Step 4: set the bash shell to root by typing (sudo bash) and then run:
echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-0/new_device (if you have a version 1 Raspberry Pi or)
echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device (if you have a version 2 Raspberry Pi)
Type (exit) to drop out of the root bash shell.
Step 5: You can check the current time on the RTC Pi with:
sudo hwclock -r
If this is the first time you have run the RTC Pi it will display a date of January 1st 2000.
Step 6: If the Raspberry Pi is connected to the internet the correct date and time should be set automatically otherwise you can set the current date and time using:
date -s "2 OCT 2006 18:00:00"
You can check the current linux date with the command (date). To save the date onto the RTC Pi use the following command:
sudo hwclock -w
Verify the date has been saved onto the RTC Pi with:
sudo hwclock -r
Step 7: Now you have the RTC Pi running with the current date and time the next step is to make it load when the Raspberry Pi boots.
Edit the modules file:
sudo nano /etc/modules
Add rtc-ds1307 at the end of the file and save it.
Step 8: Next you want to add the RTC Pi at boot by editing /etc/rc.local
sudo nano /etc/rc.local
Add the following at the bottom of the page above exit 0.
echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-0/new_device (if you have a version 1 Raspberry Pi or)
echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device (if you have a version 2 Raspberry Pi)
sudo hwclock -s
Save the file and reboot your Raspberry Pi.
sudo reboot
If everything worked correctly the RTC Pi should be initialised on boot and the current date and time will be loaded into Linux.