PiFace Real Time Clock

PiFace Real Time Clock is a Real Time Clock (RTC) for the Raspberry Pi.

Install

Add the pifacertc service

Attach PiFace Clock, download the install script and copy it to your SD card. Make the script executable and then run it:

chmod +x install-piface-real-time-clock.sh
sudo ./install-piface-real-time-clock.sh

Alternatively, if you have internet access then this one-liner should do the trick:

wget https://raw.github.com/piface/PiFace-Real-Time-Clock/master/install-piface-real-time-clock.sh && chmod +x install-piface-real-time-clock.sh && sudo ./install-piface-real-time-clock.sh

Enable I2C

Run:

sudo raspi-config

Then navigate to Advanced Options > I2C and select yes to enable the ARM I2C interface.

Set the correct date

Reboot and then set the correct date with sudo date -s, for example:

sudo date -s "14 JAN 2014 10:10:30"

Replace 14 JAN 2014 10:10:30 with today's date and time.

Set the hardware clock

Finally, save the system clock to the hardware clock with:

sudo hwclock --systohc

Starting and Stopping the Service

After installing, PiFace RTC will start as a service (/etc/init.d/pifacertc) on boot. You can start, stop, enable on boot and disable on boot with the following commands:

sudo service pifacertc start
sudo service pifacertc stop
sudo service pifacertc defaults  # enable on boot
sudo service pifacertc remove    # disable on boot

Old versions

If you installed PiFace RTC using the old script (earlier than 2016-05-04) then you might need to remove the following lines from /etc/rc.local:

modprobe i2c-dev
# Calibrate the clock (default: 0x47). See datasheet for MCP7940N
i2cset -y 1 0x6f 0x08 0x47
modprobe i2c:mcp7941x
echo mcp7941x 0x6f > /sys/class/i2c-dev/i2c-$i/device/new_device
hwclock --hctosys