Ultrasonic Range Finder is a simple method of calculating distance from an obstacle from a distance without any physical contact. It employs an ultrasonic distance sensor which uses sound pulses to measure distance. By emitting an ultrasonic pulse and timing how long does it takes to hear an echo, this project can easily estimate how far the object is. This project also employs a LCD to display the distance and a buzzer for cautioning if the obstacle is too close to the sensor.
To initiate a distance measurement, we need to send a 5V high signal to the Trig pin for at least 10 µs. When the module receives this signal, it will emit 8 pulses of ultrasonic sound at a frequency of 40 KHz from the transmitting transducer. Then it waits and listens at the receiving transducer for the reflected signal. If an object is within range, the 8 pulses will be reflected back to the sensor. When the pulse hits the receiving transducer, the Echo pin outputs a high voltage signal. The length of this high voltage signal is equal to the the total time the 8 pulses take to travel from the transmitting transducer, be reflected off the object, and travel back to the receiving transducer. However, since we only want to measure the distance to the object, we divide this time in half to get the time variable in the d = s x t equation above. Since the speed of sound is known, we also know the s variable, and now we can solve the equation for distance.
Step 1: Components Required:
1. Arduino (I have used Uno)
2. Ultrasonic Range Sensor (HC-SR04)
The HC-SR04 ultrasonic range finder has four pins: Vcc, Trig, Echo, and GND. The Vcc pin supplies the power to generate the ultrasonic pulses. The GND pin is connected to ground. The Trig pin is where the Arduino sends the signal to start the ultrasonic pulse. The Echo pin is where the ultrasonic range finder sends the information about the duration of the trip taken by the ultrasonic pulse to the Arduino.
3. Piezo Buzzer
5. Trim Pot
6. USB cable
7. Jumper wires
Step 2: Connections
The connections for the circuit is quite easy. I have attached a Fritzing document for the connections.
Step 3: Code
The code for this project is very simple. I have attached the doc for the code. Make sure you connect the correct pin numbers of the LCD according to your code.