[TC] Arduino based distance sensor

Posted by Jayesh Yewale Posted on 9:27:00 PM with No comments

Here is a simple tutorial to build a Distance sensor which will show the distance from the distance sensor HC-SR04 ( Or any other compatible devices) to the wall or obstacles in front of the sensor in CentiMeters.This project uses a HCR-SR04 distance sensor and atmega 328 or any other atmega chip which is programmed using a arduino programming kit, SO the project is based on arduino. But our final Circuit will be a standalone circuit without attached arduino programmer.Hardware Used:

HC-SR04It is a simple Ultrasonic ranging module

hc-sr04

With Specifications:

power supply :5V DCquiescent current : <2mAeffectual angle: <15°ranging distance : 2cm – 500 cmAnd whose Sequence chart is

:

sequence chart. We can send a short ultrasonic pulse at t1 , and if any obstacles is there the received ultrasonic signal is converted to an electrical signal as Echo. If a 10μs width trigger pulse is sent to the signal pin, the Ultrasonic module will output eight 40kHz ultrasonic signal and detect the echo back. The measured distance is proportional to the echo pulse width and can be calculated by the formula above. If no obstacle is detected, the output pin will give a 38ms high level signal.

Arduino : Either a Arduino Board or a Arduino IC( Atmgea 328 , Atmega 128 , Atmega 8 etc ) with a programmer is used. To know more about Arduino visit the official arduino site http://arduino.cc

16*2 LCD

2X16 LCD

Wiring:SO If you are going to use arduino board then please connect devices as following:FOR LCD:* LCD RS pin to digital pin 12* LCD Enable pin to digital pin 11* LCD D4 pin to digital pin 5* LCD D5 pin to digital pin 4* LCD D6 pin to digital pin 3* LCD D7 pin to digital pin 2* LCD R/W pin to ground* 10Komhs Variable resistor with two ends to +5v and ground and the middle wipper ti LCD pin VO.If you also have back light in your LCD and want to enable it:* LCD A to +5v , LCD K to Ground.And LCD VSS to Ground , LCD VDD to +5v.FOR HC-SR04:* VCC to +5v , Gnd to Groung* “Trig” Pin to Digital pin 7* “Echo” Pin to Digital pin 8 And if You are not using Arduino Board instead using a Arduino IC after programming it then use the following schematic:

Software:

Here is a simple version of the software:

#define trigPin 7

#define echoPin 8

void setup() {

Serial.begin (9600);

pinMode(trigPin, OUTPUT);

pinMode(echoPin, INPUT);

}

void loop() {

int timetaken, dist;

digitalWrite(trigPin, HIGH);

delayMicroseconds(1000);

digitalWrite(trigPin, LOW);

timetaken = pulseIn(echoPin, HIGH);

dist = (timetaken/2) * 0.034049 ;

if (dist >= 300 || dist <= 0){

Serial.println(“Out Of Range”);

}

else {

Serial.println(“Distance in CM: “);

Serial.print(dist);

}

delay(500);

}

Theory:

Here , we are going to calculate the distance of the sensor and any object in front of it. At t1 we send the trigger signal , and at t2 we get the echo.so dt = t2-t1And as dt is the time for the sound taken to reach to the object and return back;The exact time taken by the sound to reach the object is : dt/2Now , Normal speed of sound is: 340.29 m / s And converting it to Centimeters per Micro Seconds gives : 0.034049 CM / microsecondsThe actual distance traveled by the sound or the distance between the sensor and the object is:(dt/2) * 0.034049