This module is identical to the normal smbus module, but it allows to access
i2c devices already claimed by a kernel driveri (e.g. the hardware clock in our case).
This is the same as using the '-f' option on the i2c-get and i2c-set programs from i2c-tools.
You need the python-devel package for building this module:
sudo apt-get install python-dev
To build and install:
# For Python 2
$ make clean
$ make install
# For Python 3
$ make clean
$ PYTHON=python3 make install
This will install the module in the directory: /home/pi/.local/lib/python2.7/site-packages for Python 2
and in the directori /home/pi/.local/lib/python3.x/site-packages for Python 3..
Programs using this module therefore need to run as user pi.