Measuring Distance with Raspberry Pi and HC SR04 Utrasonic Sensor from I...

For Arduino Ultrasonic Module HC-SR04 Distance Transducer Sensor

http://www.icstation.com/arduino-ultrasonic-module-sr04-distance-transducer-sensor-p-1389.html 

1. Product feature
HC-SR04
ultrasonic module can offer non-contact distance sensing function with
the range of 2cm - 400cm. And the range accuracy is up to 2mm. This
module includes ultrasonic transmitter, receiver and control circuit.

2. Module technical parameters

• Working Voltage : 5V(DC)
• Static current: Less than 2mA.
• Output signal: Electric frequency 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 signal: 10us TTL impulse
• Echo signal : output TTL PWL signal