Real Time Clock Configuration
Real Time Clock
based on the PCF8523, an I2C device at location 0x68. Follow the steps below to configure the RTC.
Step 1 - Install Updates
pi@raspberrypi ~ $ sudo apt-get update
pi@raspberrypi ~ $ sudo apt-get upgrade
pi@raspberrypi ~ $ sudo reboot
Step 2 - Enable a RTC device tree
pi@raspberrypi ~ $sudo nano /boot/config.txt
Edit the pi configuration and add an overlay for the PCF8523:
pi@raspberrypi ~ $dtoverlay=i2c-rtc,pcf8523
Step 3 - Turn off the fake hardware clock
pi@raspberrypi ~ $ sudo apt-get -y remove fake-hwclock
pi@raspberrypi ~ $ sudo update-rc.d -f fake-hwclock remove
pi@raspberrypi ~ $ sudo systemctl disable fake-hwclock
Step 4 - Enable the real hardware RTC
pi@raspberrypi ~ $ sudo nano /lib/udev/hwclock-set
Comment out these three lines:
#if [ -e /run/systemd/system ] ; then
# exit 0
#fi
Comment out these two lines
#/sbin/hwclock --rtc=$dev --systz --badyear
#/sbin/hwclock --rtc=$dev --systz
Step 5 - Set the clock
When you initially get the clock working, the clock will have the wrong date and time.
Read the current hardware clock data and time
pi@raspberrypi ~ $ sudo hwclock -D -r
Set the correct Raspberry Pi date and time
pi@raspberrypi ~ $ date --set="20200413 21:14"
Write the correct date and time to the hardware RTC
pi@raspberrypi ~ $ sudo hwclock -w