Sunday, November 11, 2012

HC-SR04 Ultrasonic Sensor


Introduction:

The HC-SR04 Ultrasonic Sensor is a very affordable proximity/distance sensor that has been used mainly for object avoidance in various robotics projects . It essentially gives your Arduino eyes / spacial awareness and can prevent your robot from crashing or falling off a table. It has also been used in turret applications, water level sensing, and even as a parking sensor. This simple project will use the HC-SR04 sensor with an Arduino and a Processing sketch to provide a neat little interactive display on your computer screen.



Parts Required:
Freetronics Eleven or any compatible Arduino.
HC-SR04 Ultrasonic Sensor
Mini Breadboard 4.5cm x 3.5cm
Protoshieldand female header pins (not essential - but makes it more tidy)
Wiresto connect it all together




The Video:




The Arduino Sketch:



     The above sketch was created using Fritzing.





Arduino Code:
You can download the Arduino IDE from this site.

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/*
 HC-SR04 Ping distance sensor:
 VCC to arduino 5v 
 GND to arduino GND
 Echo to Arduino pin 7 
 Trig to Arduino pin 8
 
 This sketch originates from Virtualmix: http://goo.gl/kJ8Gl
 Has been modified by Winkle ink here: http://winkleink.blogspot.com.au/2012/05/arduino-hc-sr04-ultrasonic-distance.html
 And modified further by ScottC here: http://arduinobasics.blogspot.com.au/2012/11/arduinobasics-hc-sr04-ultrasonic-sensor.html
 on 10 Nov 2012.
 */


#define echoPin 7 // Echo Pin
#define trigPin 8 // Trigger Pin
#define LEDPin 13 // Onboard LED

int maximumRange = 200; // Maximum range needed
int minimumRange = 0; // Minimum range needed
long duration, distance; // Duration used to calculate distance

void setup() {
 Serial.begin (9600);
 pinMode(trigPin, OUTPUT);
 pinMode(echoPin, INPUT);
 pinMode(LEDPin, OUTPUT); // Use LED indicator (if required)
}

void loop() {
/* The following trigPin/echoPin cycle is used to determine the
 distance of the nearest object by bouncing soundwaves off of it. */ 
 digitalWrite(trigPin, LOW); 
 delayMicroseconds(2); 

 digitalWrite(trigPin, HIGH);
 delayMicroseconds(10); 
 
 digitalWrite(trigPin, LOW);
 duration = pulseIn(echoPin, HIGH);
 
 //Calculate the distance (in cm) based on the speed of sound.
 distance = duration/58.2;
 
 if (distance >= maximumRange || distance <= minimumRange){
 /* Send a negative number to computer and Turn LED ON 
 to indicate "out of range" */
 Serial.println("-1");
 digitalWrite(LEDPin, HIGH); 
 }
 else {
 /* Send the distance to the computer using Serial protocol, and
 turn LED OFF to indicate successful reading. */
 Serial.println(distance);
 digitalWrite(LEDPin, LOW); 
 }
 
 //Delay 50ms before next reading.
 delay(50);
}

The code above was formatted using hilite.me





Processing Code:
You can download the Processing IDE from this site.

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/* The following Processing Sketch was created by ScottC on
 the 10 Nov 2012 : http://arduinobasics.blogspot.com/
 
 Inspired by this Processing sketch by Daniel Shiffman:
 http://processing.org/learning/basics/sinewave.html
 
*/
import processing.serial.*;


int numOfShapes = 60; // Number of squares to display on screen 
int shapeSpeed = 2; // Speed at which the shapes move to new position
 // 2 = Fastest, Larger numbers are slower

//Global Variables 
Square[] mySquares = new Square[numOfShapes];
int shapeSize, distance;
String comPortString;
Serial myPort;

/* -----------------------Setup ---------------------------*/
void setup(){
 size(displayWidth,displayHeight); //Use entire screen size.
 smooth(); // draws all shapes with smooth edges.
 
 /* Calculate the size of the squares and initialise the Squares array */
 shapeSize = (width/numOfShapes); 
 for(int i = 0; i<numOfShapes; i++){
 mySquares[i]=new Square(int(shapeSize*i),height-40);
 }
 
 /*Open the serial port for communication with the Arduino
 Make sure the COM port is correct - I am using COM port 8 */
 myPort = new Serial(this, "COM8", 9600);
 myPort.bufferUntil('\n'); // Trigger a SerialEvent on new line
}

/* ------------------------Draw -----------------------------*/
void draw(){
 background(0); //Make the background BLACK
 delay(50); //Delay used to refresh screen
 drawSquares(); //Draw the pattern of squares
}


/* ---------------------serialEvent ---------------------------*/
void serialEvent(Serial cPort){
 comPortString = cPort.readStringUntil('\n');
 if(comPortString != null) {
 comPortString=trim(comPortString);
 
 /* Use the distance received by the Arduino to modify the y position
 of the first square (others will follow). Should match the
 code settings on the Arduino. In this case 200 is the maximum
 distance expected. The distance is then mapped to a value
 between 1 and the height of your screen */
 distance = int(map(Integer.parseInt(comPortString),1,200,1,height));
 if(distance<0){
 /*If computer receives a negative number (-1), then the
 sensor is reporting an "out of range" error. Convert all
 of these to a distance of 0. */
 distance = 0;
 }
 }
}


/* ---------------------drawSquares ---------------------------*/
void drawSquares(){
 int oldY, newY, targetY, redVal, blueVal;
 
 /* Set the Y position of the 1st square based on 
 sensor value received */
 mySquares[0].setY((height-shapeSize)-distance);
 
 /* Update the position and colour of each of the squares */
 for(int i = numOfShapes-1; i>0; i--){
 /* Use the previous square's position as a target */
 targetY=mySquares[i-1].getY();
 oldY=mySquares[i].getY();
 
 if(abs(oldY-targetY)<2){
 newY=targetY; //This helps to line them up
 }else{
 //calculate the new position of the square
 newY=oldY-((oldY-targetY)/shapeSpeed);
 }
 //Set the new position of the square
 mySquares[i].setY(newY);
 
 /*Calculate the colour of the square based on its
 position on the screen */
 blueVal = int(map(newY,0,height,0,255));
 redVal = 255-blueVal;
 fill(redVal,0,blueVal);
 
 /* Draw the square on the screen */
 rect(mySquares[i].getX(), mySquares[i].getY(),shapeSize,shapeSize);
 }
}

/* ---------------------sketchFullScreen---------------------------*/
// This puts processing into Full Screen Mode
boolean sketchFullScreen() {
 return true;
}

/* ---------------------CLASS: Square ---------------------------*/
class Square{
 int xPosition, yPosition;
 
 Square(int xPos, int yPos){
 xPosition = xPos;
 yPosition = yPos;
 }
 
 int getX(){
 return xPosition;
 }
 
 int getY(){
 return yPosition;
 }
 
 void setY(int yPos){
 yPosition = yPos;
 }
}

The code above was formatted using hilite.me

 
 



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