HC-SR04 Ultrasonic Range Finder

This ultrasonic range finder is supprisingly accurate and easy of use.
You only need to send it a 10us TTL pulse and will receive a pulse withits width indicating detected distance.

Features

•  Distance measurement range: 2cm - 400cm
• Accuracy: 0.3cm
• Detect angle: 15 degree
• Single +5V DC operation
• Current comsuption: 15mA

How Works

HC-SR04 consists of ultrasonic transmitter, receiver, and controlcircuits.
When trigged it sends out a series of 40KHz ultrasonic pulses andreceives echo from an object.
The distance between the unit and the object is calculated by measuringthe traveling time of sound and output it as the width of a TTL pulse.

How To Use It

To measure distance you need to generate a trig signal and drive it tothe Trig Input pin.
The trig signal leve must meet TTL level requirements (i.e. High level> 2.4V, low level < 0.8V) and its width must be greater than 10us.
At the same time you need to monitor the Output pin by measuring thepulse width of output signal. The detected distance can be calculatedby the formula below.

Distance = ( Pulse Width * Sound Speed) /  2

where the pulse width is in unit of second and sound speed is in unitof meter/second.
Normally sound speed is 340m/s under room temperature.


Notes:

1. The width of trig signal must be greater than 10us
2. The repeat interval of trig signal should be greater than 60ms toavoid interference between connective measurements.
   

Specifications

Operating Voltage
+5V DCOperating Current
15mAOperating Frequency40KHzMaximum Distance400cmMinimum Distance2cmDetect Angle15 degreeResolution0.3cmInput Trig Signal>10us TTL pulseOutput SignalTTL pulse with widthrepresenting distanceWeight9 g
Dimension45 x 20 x 15 mm

Documents

•    Manual