/* * ////////////////////////////////////////////////// * //making sense of the Parallax PIR sensor's output * ////////////////////////////////////////////////// * * Switches a LED according to the state of the sensors output pin. * Determines the beginning and end of continuous motion sequences. * * @author: Kristian Gohlke / krigoo (_) gmail (_) com / http://krx.at * @date: 3. September 2006 * * kr1 (cleft) 2006 * released under a creative commons "Attribution-NonCommercial-ShareAlike 2.0" license * http://creativecommons.org/licenses/by-nc-sa/2.0/de/ * * * The Parallax PIR Sensor is an easy to use digital infrared motion sensor module. * (http://www.parallax.com/detail.asp?product_id=555-28027) * * The sensor's output pin goes to HIGH if motion is present. * However, even if motion is present it goes to LOW from time to time, * which might give the impression no motion is present. * This program deals with this issue by ignoring LOW-phases shorter than a given time, * assuming continuous motion is present during these phases. * */ ///////////////////////////// //VARS //the time we give the sensor to calibrate (10-60 secs according to the datasheet) int calibrationTime = 45; //the time when the sensor outputs a low impulse long unsigned int lowIn; //the amount of milliseconds the sensor has to be low //before we assume all motion has stopped long unsigned int pause = 5000; boolean lockLow = true; boolean takeLowTime; int pirPin = 3; //the digital pin connected to the PIR sensor's output int ledPin = 11; int led1=8; int led2=7; ///////////////////////////// //SETUP void setup(){ Serial.begin(9600); pinMode(pirPin, INPUT); pinMode(ledPin, OUTPUT); pinMode(led1,OUTPUT); pinMode(led2,OUTPUT); digitalWrite(pirPin, LOW); //give the sensor some time to calibrate Serial.print("calibrating sensor "); for(int i = 0; i < calibrationTime; i++){ Serial.print("."); delay(1000); } Serial.println(" done"); Serial.println("SENSOR ACTIVE"); delay(50); } void alert() { digitalWrite(led1,HIGH); digitalWrite(led2,LOW); delay(50); digitalWrite(led2,HIGH);digitalWrite(led1,LOW); delay(50); } void loop(){ if(digitalRead(pirPin) == HIGH){ analogWrite(ledPin, 50); alert(); digitalWrite(led1,LOW); digitalWrite(led2,LOW); ;//the led visualizes the sensors output pin state if(lockLow){ //makes sure we wait for a transition to LOW before any further output is made: lockLow = false; Serial.println("---"); Serial.print("motion detected at "); Serial.print(millis()/1000); Serial.println(" sec"); delay(50); } takeLowTime = true; } if(digitalRead(pirPin) == LOW){ digitalWrite(ledPin, LOW); //the led visualizes the sensors output pin state if(takeLowTime){ lowIn = millis(); //save the time of the transition from high to LOW takeLowTime = false; //make sure this is only done at the start of a LOW phase } //if the sensor is low for more than the given pause, //we assume that no more motion is going to happen if(!lockLow && millis() - lowIn > pause){ //makes sure this block of code is only executed again after //a new motion sequence has been detected lockLow = true; Serial.print("motion ended at "); //output Serial.print((millis() - pause)/1000); Serial.println(" sec"); delay(50); } } }