PIR Sensor - How do I connect it to the board

Other Hardware Sensors
1

I am no electrician and spent only a few hours with my Arduino. Yesterday I just picked up a PIR Sensor and I'm not sure where to start connecting the PIR or any other sensor for that matter. The LED needed a resistor and I'm guessing my answer is somewhere in this description of the PIR quoted below. Thanks for any help, explanation, or smart ars comments.

Key Specifications
? Power Requirements: 3 to 6 VDC; 12 mA @ 3 V, 23 mA @ 5 V
? Communication: Single bit high/low output
? Operating temperature: 32 to 122 °F (0 to 50 °C)
? Dimensions: 1.41 x 1.0 x 0.8 in (35.8 x 25.4 x 20.3 cm)

http://www.parallax.com/Portals/0/Downloads/docs/prod/sens/555-28027-PIRSensor-v2.0.pdf

2

Ohm's Law
V = IR

Which current(I) and Voltage do I pick from the sensor specs to do the calculation?

3

What is the spec of the LED you are trying to drive?

4

It's a motion sensor, the LED was my only point of reference and it needed a resistor. I'm curious how to hook a motion sensor to the Arduino.

Key Specifications
? Power Requirements: 3 to 6 VDC; 12 mA @ 3 V, 23 mA @ 5 V
? Communication: Single bit high/low output
? Operating temperature: 32 to 122 °F (0 to 50 °C)
? Dimensions: 1.41 x 1.0 x 0.8 in (35.8 x 25.4 x 20.3 cm)

5

You could power it from the 5V pin, or you could actually power it from an output pin - 23mA is well below the limit of 40mA.
No need for a resistor.

6

Thanks!

7

So I connected the PIR to Analogue 0 and to Digital 13 and when I print the value it is 0 even if I wave my hand in front of it. Any ideas?

/*
 *  Motion Detection 
 */

int motionPin = 0; //the motion sensor

void setup()
{
//  pinMode(ledPin, OUTPUT); //sets the led pin to output
  Serial.begin(9600);
}

void loop()
{
 int motionLevel = analogRead(motionPin); //Read the motionLevel
 Serial.println(motionPin);
 
}

motion.JPG
motion.JPG800×600 148 KB

8

Digital not analogue, see the pic and the code

/*

  • Motion Detection
    */

int calibrationTime = 30;
int motionPin = 3; //the motion sensor

void setup()
{
pinMode(motionPin, INPUT); //sets the led pin to output
digitalWrite(motionPin, LOW);
Serial.begin(9600);

}

void loop()
{
Serial.println(digitalRead(motionPin));

}

motion.JPG
motion.JPG1067×800 224 KB

9

What is connected to pin 13?
The PIR?
I don't see where you've turned it on.

10

The PIR is connected to pin 3. What do you mean by turned it on?

11 
 pinMode(motionPin, INPUT); //sets the led pin to output
    digitalWrite(motionPin, LOW);

Well, that's about as much confusion as I've seen in two lines of C.

What do you mean by turned it on?

"Supplied it with electrical current"

12

oops, "//sets the led pin to output" was a cut and paste mistake

pinMode(motionPin, INPUT); //sets the led pin to output
digitalWrite(motionPin, LOW);

13

I don't think the digitalWrite is necessary - the built-in pullups are disabled by default.

14

Thanks, I'll try it without.