Posts Tagged ‘motion sensor’

Arduino – (Very) Basic motion tracking with 2 PIR sensors

Arduino 2PIR motion tracker

Took me a little while to get started but I’ve managed to wire 2 PIR infrared sensors with an Arduino to sense motion either on the left or on the right side. The result will trigger an LED to represent each PIR sensor then I also added in a servo to be controlled – so it turns left when triggered by the left sensor and so on.

First have a look at my previous tutorial – Arduino PIR motion detector circuit. Now we’re going to use 2 of them and this isn’t that different from just using one of them. However this is only a first attempt so I’ve not calibrated anything properly, for instance we can’t ascertain velocity or true direction of movement because these sensors aren’t that precise and have a wide range of detection. But hey, it’s a start!

Arduino PIR Motion Sensor Circuit Parts

2x 220 Ohm resistor (Red, Red, Brown, Gold)
2x 10K Ohm resistor (Brown, Black, Orange, Gold)
2x PIR sensor
1x Servo (has to need no more than 5v supply)
2x LED
Arduino Deumilanove w/ ATMEGA328
Breadboard / Prototyping board
Jumper/ Connector wires
Optional 9V DC power supply or use the USB power for the Arduino
You will also need a soldering iron and solder if you use the same PIR as myself.
Some sort of  temporary adhesive to hold the sensors in place.

Arduino Infrared Motion Detector Circuit

So you’ll see that its really just a lot of wires. The PIRs I’ve soldered on the wires and on their output pin there’s a 10K Ohm resistor for each going between them and the positive rail on the breadboard. The LED’s are the same layout as the basic blink tutorials, 220 Ohm resistor between the positive pin (the longer one) and the Arduino pin.


PIR Motion Sensor Arduino Code

This isn’t too bad. Basically we set 2 sensors and have a few if statements to do shit based on if they turn on or off, so essentially they’re treated just like a couple of switches.
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LUCKYLARRY.CO.UK - 2 3pin PIR sensors to track basic motion.

We have 1 sensor for left, 1 for right.

The left sensor is triggered, the LED for the left comes on and the servo moves until no motion is detected.
The same happens if the right sensor is triggered.

If both sensors detect motion then its likely the object may be between the 2 but given the field of detection
its not going to be precice. Enjoy!


#include                                                 // Include servo library, you can get it from
Servo myservo;                                                    // Create a servo object
int pos = 0;                                                      // Variable to store the servo position in degrees
int pinPIRleft = 4;                                               // left infrared sensor, digital pin 4
int pinLEDleft = 8;	                                          // left LED, digital pin 8
int pinPIRright = 2;                                              // right sensor, digital pin 2
int pinLEDright = 10;                                             // right LED, digital pin 10

void setup() {
  pinMode(pinLEDleft, OUTPUT);                                    // set LEDs as outputs
  pinMode(pinLEDright, OUTPUT);
  pinMode(pinPIRleft, INPUT);                                     // set sensors as inputs
  pinMode(pinPIRright, INPUT);
  myservo.attach(9);                                              // set the servo to digital pin 9

void loop() {

  if (digitalRead(pinPIRleft) == LOW) {                           // if left detects motion
    digitalWrite(pinLEDleft, HIGH);                               // turn on LED
    if ((pos < 180) && (digitalRead(pinPIRright) == HIGH)) {      // if less than 180 degrees and the right sensor is off then move servo
      pos += 1;                                                   // increment servo degrees by +1
      myservo.write(pos);                                         // write the position to the servo
  } else {
    digitalWrite(pinLEDleft, LOW);                                // otherwise turn off LED and no servo movement

  if (digitalRead(pinPIRright) == LOW) {
    digitalWrite(pinLEDright, HIGH);
    if ((pos >= 1) && (digitalRead(pinPIRleft) == HIGH)) {
      pos -= 1;
  } else {
    digitalWrite(pinLEDright, LOW);

  if ((digitalRead(pinPIRleft) == LOW) && (digitalRead(pinPIRright) == LOW)) {
    // do something here if both sensors detect movement.

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And here it is in action:

Well, you could add a 3rd sensor to validate that an object is in front of both sensors, you’ll see that I’ve angled my sensors to try and work this with just 2 sensors. Perhaps limiting the field of detection for each sensor might also be a good thing to make it more precise.

Arduino – motion triggered camera

Nikon D80 Motion sensor trigger

So having worked out that I can make a remote for my Nikon D80 to do some timelapse photography. I started thinking of things I can do to trigger the remote, below video shows it working but you’ll need sound to hear the shutter going.

First of all check out my tutorial for making the remote as this builds on that tutorial – also saves me having to recap and explain that. Arduino Nikon intervalometer infrared remote for timelapse photography.

Ok so now you know how I’m going to trigger the camera to take pictures. So now we need the sensor, for this I’m going to use a PIR (Pyroelectric InfraRed sensor) IC that works like a switch turning on when motion is detected, the one I’m using is basically a couple of IR emitters and sensors under a Fresnel lens – word of warning make sure you get the power supply right as they tend to smoke otherwise!. It works by measuring any difference to the background temperature and infrared radiation. I’ve also added an LED to signal when the PIR is on or off.

The biggest challenge for this was making sure the camera didn’t keep triggering for the length of time the PIR was active – sometimes it would be active for 5 or seconds after initial movement, so I wanted to capture say 2 photos for each time it was triggered.

For lazyness I’ve left my camera in auto setting so that it *should* autofocus along with everything else – e.g. exposure times and apertures.

Arduino Motion Tracker Parts

220 Ohm resistor (Red, Red, Brown, Gold)
10K Ohm resistor (Brown, Black, Orange, Gold)
PIR sensor
Infrared emitting diode
Arduino Deumilanove w/ ATMEGA328
Breadboard / Prototyping board
Jumper/ Connector wires
Optional 9V power supply (here) or use the USB power for the Arduino
You will also need a soldering iron and solder if you use the same PIR as myself.

The Arduino Motion Detector Circuit

You may not be able to see but I’ve used the power supply from the Arduino to power the breadboard. The PIR gets its supply from this and there’s a 10k Ohm resistor between its output pin and pin 4 on the Arduino. The LED has a 220 Ohm resistor between that and the digital pin 9. The IR LED I’ve left in pin 13 and grounded – for a better system I would solder on a couple of wires to allow more flexibility with transmitting the signal. Also for the PIR, the one I have I had to solder a few jumper wires into the back of it just so you know.


Arduino Motion Sketch / Code

Based off of my remote tutorial I’ve just added in a few extra things really. An output for the LED, an input for the PIR and a chunk of code to limit the taking of photos.
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LUCKYLARRY.CO.UK - IR Remote control for Nikon using Arduino with motion trigger

Uses a PIR sensor to trigger the camera remote/ IR led if a change in background
temperature is detected.


int currentState = 0;                                   // set a variable to store a count.
int pinPIR = 4;                                         // digital pin 4 for PIR
int pinLED = 9;                                         // digital pin 9 for LED
int pinIRLED = 13;                                      // assign the Infrared emitter/ diode to pin 13

void setup() {
  pinMode(pinIRLED, OUTPUT);                            // set the pin as an output
  pinMode(pinLED, OUTPUT);                              // set the LED pin as ouput
  pinMode(pinPIR, INPUT);                               // set the PIR pin as an input

// sets the pulse of the IR signal.
void pulseON(int pulseTime) {
  unsigned long endPulse = micros() + pulseTime;        // create the microseconds to pulse for
  while( micros() < endPulse) {
    digitalWrite(pinIRLED, HIGH);                       // turn IR on
    delayMicroseconds(13);                              // half the clock cycle for 38Khz (26.32×10-6s) - e.g. the 'on' part of our wave
    digitalWrite(pinIRLED, LOW);                        // turn IR off
    delayMicroseconds(13);                              // delay for the other half of the cycle to generate wave/ oscillation


void pulseOFF(unsigned long startDelay) {
  unsigned long endDelay = micros() + startDelay;       // create the microseconds to delay for
  while(micros() < endDelay);

void takePicture() {
  for (int i=0; i < 2; i++) {
    pulseON(2000);                                      // pulse for 2000 uS (Microseconds)
    pulseOFF(27850);                                    // turn pulse off for 27850 us
    pulseON(390);                                       // and so on
  }                                                     // loop the signal twice.

void loop() {

  if ((digitalRead(pinPIR) == LOW) && (currentState <= 2)) { // count to limit the taking of photos
    takePicture();                                      // take the picture
    digitalWrite(pinLED, HIGH);                         // turn LED on
  } else {
    digitalWrite(pinLED, LOW);
    currentState = 0;                                   //reset the count when the PIR is off.

  delay(2000);                                          // delay for 2 seconds - 2 seconds between taking photos if the PIR is active for more than 2 seconds.

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I think adding in another PIR would help me make some kind of turret system. Also you could use the ultrasonic range finder jobby, the SRF-05, to detect the distance and if less than say 3 metres take the photo etc.. I'm also going to try and setup a trip-wire system to trigger the camera :)