HC-SR04 - 4 pin Ultrasonic Distance Sensor Module With Mounting bracket for Arduino

Low cost ultrasonic transducer for measuring distances - used with Arduinos and other microcontrollers. Simple hookup, only Vcc + Gnd + Trig + Echo, this is the most cost effective way to measure distance with a microcontroller

Use  Arduino to create a very easy to use ultrasonic transducer

Features 

• Working Voltage: 5V(DC)
• Current: Less than 2mA
• Output Signal: high level 5V, low level 0V
• Sensor Angle: Not more than 15 degrees
• Detection Distance: 2cm-450cm
• High Precision: Up to 0.3cm
• Input Trigger: 10us TTL impulse
• Echo Signal: output TTL PWL signal

Detail Operation:

A 10us pulse is sent to the module, the module sends 8 x ultrasonic pulses of 40KHz out.

If a return pulse is detected, the High Level Pulse Width is a function of distance

a 38ms pulse width = no return pulse 

distance = (high level time * sound velocity (340M/S) / 2