PIR stands for Passive InfraRed. The
PIR Sensor detects motion up to 20 feet away by using a Fresnel lens
and infrared-sensitive element to detect changing patterns of passive
infrared emitted by objects in its vicinity. In this exercise you will build a simple motion detector using a PIR sensor. You will need the following components (from your kit):
Note: You will have to carefully place the PIR sensor on the corner of your breadboard so that it fits. Once you have built this circuit upload the following code: int ledPin = 13; // led connected to control pin 13 int pirSensor = 0; // the passive infra red sensor will be plugged at analog pin 0 byte val = 0; // variable to store the value read from the sensor pin int statePin = HIGH; // variable used to store the last LED status, to toggle the light int THRESHOLD = 5; // threshold value to decide when detected motion is movement or not void setup() { pinMode(ledPin, OUTPUT); // declare the ledPin as as OUTPUT Serial.begin(9600); // use the serial port } void loop() { val = analogRead(pirSensor); // read the sensor and store it in the variable "val" if (val >= THRESHOLD) { statePin = !statePin; // toggle the status of the ledPin (this trick doesn't use time cycles) digitalWrite(ledPin, statePin); // turn the led on or off Serial.println("Motion Detected"); // send the string "Motion Detected" back to the computer, followed by newline } delay(150); // A delay to avoid overloading the serial port } |