DS3231 RTC Module

Targets Raspberry Pi
1

If you need your Pi to save the date and time when shut down and it does not have internet access to use NTP servers you need an RTC hwclock.
I just bought a DS3231 RTC Module and it was really easy to install and use.

1. Shut down your Pi2/Zero.
2. Plug in the module on the first 5 pins on the left pin row.
3. Edit /boot/confix.txt to add ‘dtoverlay=i2c-rtc,ds3231’.
4. Reboot the Pi.
5. Sync the swclock with the DS3231: sudo hwclock --systohc
6. Check to see if the hwclock now has the correct time set: sudo hwclock -r

All done :slight_smile:

2

I have now seen that the above instructions doesn’t seem to work on Jessie, but fear not. These seems to:

  1. Shut down your Pi.
  2. Plug in the module on the first 5 pins on the left pin row.
  3. Edit /boot/config.txt to add ‘dtoverlay=i2c-rtc,ds3231’ to the end of the file.
  4. Edit /lib/udev/hwclock-set
    Out-comment(#) the following:

#if [-e /run/systemd/system ]; then #exit #fi
And the two lines containing ‘–systz’.
5. Save the file and Reboot the Pi.
6. Set the system clock to the correct date/time: ‘sudo date -s “17 FEB 2016 21:00:00”’
7. Write the system time to the RTC module: sudo hwclock -w
8. Check to see if the time has been successfully written to the RTC: sudo hwclock -r

For the final test, shutdown the Pi, remove it’s internet connection(cable or wi-fi).
Remove the power cable and let it be shut down over night. Check the time on the next boot.

It has worked for me on two Pi Zeros running Jessie, hope it does for you :slight_smile: