Intro: Raspberry Pi - Real Time Clock (RTC)
In this project, we will be making a Real Time Clock (RTC) which keep the time for your Raspberry Pi even if it is turned off.
Real Time Clock is essential for every Micro-controllers to keep the time even if it is turned off. Without a Network Time Protocol (NTP), the system time and date will almost certainly be wrong. For some projects this is a vital problem especially if you are logging time stamps or performing other time sensitive operations.
It’s a fairly easy project and can be used either on its own or part of something bigger (Check it Out >> Raspberry Pi - Data Logging).
Step 1: List of Materials
For this project, we will be using:
- Raspberry Pi
- DS3231 module cost: ~2.00 USD
- Jumper Wire or Custom Proto Shield (Check it out how to make it >> )
Step 2: Hardware Connections
In general, the connections are very simple. Follow the instructions and images above, and you should have no problems.
Connecting RTC Module
- the VCC pin on Raspberry's 3V pin (P1-01)
- the GND pin to Raspberry’s GND (P1-06)
- the SDA (Serial Data Line) to Raspberry's pin 3, and
- the SCL (Serial Clock Line) to Raspberry's pin 5
P.S. Raspberry Pi first pin had a square soldering hole.
Step 3: Raspberry Pi Programming
First, setup the module
Update and upgrade your Pi
sudo apt-get update<br>sudo apt-get -y upgrade
Modify your system file
sudo nano /etc/modules
change or add the /etc/modules
Next, setup Raspberry's i2c communication
detect your rtc device
sudo i2cdetect -y 1<br>or<br>sudo i2cdetect -y 0
Modify your system line
sudo nano /etc/rc.local
Add the following two lines before the exit 0 line :
echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device <br>hwclock -s
Reboot your pi
Finally, setup date on RTC
change your Raspberry Pi system time
sudo date -s "20 NOV 2015 18:49:00"
write the rtc module
sudo hwclock -w
match your system and rtc module
sudo date; sudo hwclock -r
Step 4: Enjoy!
The final test is to determine if the RTC module is keeping time and that the Pi will use that time when it boots. The best way to do that is to :
- Power down Raspberry Pi (sudo halt),
- Remove the power cable,
- Remove the network connection ,
(Pi automatically synchronize time when connect to an internet)
- Attach the Pi to a monitor and keyboard,
- Leave it overnight
- Power it up and use “sudo date” to see what time the Pi thinks it is
After making sure that everything works smoothly, you can take this project into bigger project (Check it Out >> Raspberry Pi - Data Logging)!