Note: Use the WIKI for latest informationen!

An ultrasonic sensor is an excellent way to detect obstacles.

Example: HC-SR04

• Distance 2 to 450 cm
• Current 15 mA

Wiring
Ultrasonic Module Trigger — Arduino Digital Pin
Ultrasonic Module Echo  — Arduino Digital Pin
Ultrasonic Module VCC (+5V) — Arduino VCC (+5V)
Ultrasonic Module GND — Arduino GND

  Demo Video

 
An internal schematics of the sensor can be found here.