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April 12, 2017 04:18
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PIR sensor for Arduino UNO
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/* | |
* ////////////////////////////////////////////////// | |
* //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 = 30; | |
//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 = 13; | |
///////////////////////////// | |
//SETUP | |
void setup(){ | |
Serial.begin(9600); | |
pinMode(pirPin, INPUT); | |
pinMode(ledPin, 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); | |
} | |
//////////////////////////// | |
//LOOP | |
void loop(){ | |
if(digitalRead(pirPin) == HIGH){ | |
digitalWrite(ledPin, HIGH); //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); | |
} | |
} | |
} |
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