sudo apt-get install build-essential php5 php5-dev

cd php-sdhumming/src
phpize
./configure
make
sudo make install

Edit php-sdhumming/conf/etc/php5/mods-available/sdhumming.ini
Adjust the value of sdhumming.model and sdhumming.info

cd php-sdhumming/conf
sudo cp ./etc/php5/mods-available/sdhumming.ini /etc/php5/mods-available/sdhumming.ini 
cd /etc/php5/cli/conf.d/
sudo ln -s ../../mods-available/sdhumming.ini 50-sdhumming.ini 
cd /etc/php5/apache2/conf.d/
sudo ln -s ../../mods-available/sdhumming.ini 50-sdhumming.ini
sudo service apache2 restart