Update README.md

README.md

@@ -9,7 +9,7 @@ On Raspberry Pi, issue these commands to install required packages need to run t
 
 ```
 $ sudo apt-get update
-$ sudo apt-get install python-gi-cairo python-smbus
+$ sudo apt-get install python-gi-cairo python-smbus i2c-tools
 ```
 
 
@@ -27,6 +27,23 @@ $ python pps-singletact
 To reset the graph, long touch at upmost-left screen (near the 700 value)
 Or by mouse triple clicks or by SPACE key (keyboard)
 
+By default, I2C (the communication protocol used to communicate with the SingleTact device) is not enabled on the Pi. I2C can be enabled in the raspi-config tool.
+
+```
+$ sudo raspi-config
+```
+Select Advanced Options -> I2C – Enable/Disable automatic loading, and then select yes.
+
+If running Raspbian releases before 3.18 the following config file must be edited.
+```
+$ sudo nano /etc/modprobe.d/raspi-blacklist.conf 
+```
+Comment out the following by adding a “#” to the start of each line.
+```
+blacklist spi-bcm2708
+blacklist i2c-bcm2708
+```
+
 
 AUTORUN
 =======
@@ -41,7 +58,6 @@ then
 
 ```
 $ sudo top
-
 ```
 kill the python process, usually press k enter and then 9.