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 with its width indicating detected distance.
- Distance measurement range: 2cm - 400cm
- Accuracy: 0.3cm
- Detect angle: 15 degree
- Single +5V DC operation
- Current comsuption: 15mA
HC-SR04 consists of ultrasonic transmitter, receiver, and control circuits.
When trigged it sends out a series of 40KHz ultrasonic pulses and receives echo from an object.
The distance between the unit and the object is calculated by measuring the 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 to the 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 the pulse width of output signal. The detected distance can be calculated by the formula below.
Distance = ( Pulse Width * Sound Speed ) / 2
where the pulse width is in unit of second and sound speed is in unit of meter/second.
Normally sound speed is 340m/s under room temperature.
- The width of trig signal must be greater than 10us
- The repeat interval of trig signal should be greater than 60ms to avoid interference between connective measurements.
|Operating Voltage||+5V DC|
|Detect Angle||15 degree|
|Input Trig Signal||>10us TTL pulse|
|Output Signal||TTL pulse with width representing distance|
|Dimension||45 x 20 x 15 mm|