Designed to be used in Raspbian and It is a highly accurate real-time clock which connects via the GPIO port on a Raspberry Pi. It uses the GND, SDA and SCL pins.
It utilises the highly accurate NXP PCF2127AT / PCF2129AT chip and features:
- Very accurate timekeeping (typically ±3ppm or <2 minutes deviation per year)
- Integrated crystal that compensates for temperature and age
- The supplied battery will keep the time for a very long time if the device isn’t used and considerably longer if it is
- 512 bytes of static RAM protected by the backup battery
- Coin Battery Included!
Set-up with LXTerminal
1. Download the latest version operation system of Raspbian “wheezy” and install.
2. Make sure we’ve got the latest firmware drivers.
sudo apt-get update
3. Download the RTC driver
4. Extract the RTC driver
tar xzvf rtc-3.6.11.tar.gz
5. Install the RTC driver
sudo dpkg -i rtc-3.6.11.deb
6. Copy the RTC module’s boot file to the Raspberry Pi boot directory.
sudo cp /boot/vmlinuz-3.6.11-atsw-rtc+ /boot/kernel.img
7. Open the ‘modules’ file in the nano text editor
sudo nano /etc/modules
8. Add the following text
9. Press ‘CTRL + X’ to exit, Type ‘Y’ to save those changes, Press ‘Enter’ to return
10. Open ‘rc.local’ for editing
sudo nano /etc/rc.local
11. Register the RTC module and set the system clock from the RTC.
echo pcf2127a 0x51 > /sys/class/i2c-adapter/i2c-1/new_device
( sleep 2; hwclock -s ) &
12. Press ‘CTRL + X’ to exit, Type ‘Y’ to save those changes, Press ‘Enter’ to return.
14. Set the system time.
sudo date MMDDHHMMYYYY.SS (MM= Month, DD= Date, HH= Hour, MM= Minute, YYYY= Year, SS= Second )
Example 2013 Jan 4 , 11:39:00 , sudo date 010411392013.00
15. Copy the system time into the clock module
sudo hwclock -w
16. To read the time from the clock module
sudo hwclock -r
17. To copy the time from the clock module to the system
sudo hwclock -s
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