PIR sensor detects motion only when a very near motion to the IR sensor and when the cover opened

Question

I am tying to implement something using PIR sensor and Arduino UNO. I did the wiring like this

VCC - 5v
GND - GND
Dout - Pin 3

Here is my code

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)
  {
    Serial.println("Detected motion");
    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);
    }
  }
}

But after calibration its not at all showing its detects some motion when there are many. I tried more sensitivity by turning the right potentiometer all towards right (Clockwise). Still nothing detected.

Then I tried removing the White cover of sensor and it detected some motion only when I touched the sensor.

I tried with another sensor, it works the same. It detect some movement only when I touched it.

What should be wrong?? Both sensors are damaged??

Answer 1

You have provided Arduino code, but if your problem is with the sensor (as you seem to be asking in the question) then that code is just a distraction.

So apply one of the standard troubleshooting techniques: Split the system into parts, and investigate the signal(s) between those sections.

In your case, you can easily investigate just the sensor's behaviour using a DMM or scope etc. (or even a small, high-efficiency red LED with a series 220 ohm resistor to 0V, in my experience) to visualise and understand its output signal with different stimuli (no Arduino connected for this testing).

• Is the sensor's output correct, when not connected to the Arduino?
  • No - then investigate the sensor and how you are using it. Ignore the Arduino code for now.
  • Yes - then stop worrying about the sensor, as you described in the question. It's time to debug your Arduino code.