Guide to gyro and accelerometer with Arduino including Kalman filtering

@psyoptica
Yes they are, but pins can have several capabilities.

For instance you can also use any analog pin as a digital pin like so:

pinMode(A0,OUTPUT);
digitalWrite(A0,HIGH);

You can read more about it in the datasheet: http://www.atmel.com/Images/Atmel-8271-8-bit-AVR-Microcontroller-ATmega48A-48PA-88A-88PA-168A-168PA-328-328P_datasheet.pdf.