Digital I / O
http://playground.arduino.cc/Code/NewPing
http://richarduino.com/ultrasonic-sensor-arduino-project/
http://randomnerdtutorials.com/complete-guide-for-ultrasonic-sensor-hc-sr04/
0,50 €
Aliexpress
Suport sensor ultrasons HC-SR04 (4 forats)
Suport sensor ultrasons HC-SR04 (2 forats)