PIR Motion Detector

Node library for PIR sensor

I used this one from Adafruit.

Adafruit has a lovely writeup on how PIRs work; I encourage you to read the details here. Here are some of the key pieces of information:

• IR detects warm bodies.
• There are two beams of IR sensitivity on the PIR.
• If both beams detect the same amount of IR, the sensor records that no warm bodies are present.
• When a warm body enters the field, the sensor records a positive charge differential.
• When a warm body leaves the field, the sensor records a negative charge differential.

Materials

• PIR motion detector
• Tessel

Connecting

The PIR I used has three pins. Here's how you connect it to Tessel:

• +5V on the PIR goes to Vin on Tessel's GPIO bank (this pin is 5V when Tessel is powered over USB)
• GND goes to any of the various GND pins on Tessel. There's one right next to Vin on the GPIO bank.
• OUT, the signal pin, goes to any of Tessel's various digital (G) pins. Note that the signal works on a maximum of 3.3V.

I've left the PIR sensor in the retriggering position (H for the Adafruit one), so the signal pin will be pulled high as long as the sensor detects movement.

Installation

npm install pir

Example

/*********************************************
This basic PIR example emits events when
a body is detected and when a body exits
the field.
*********************************************/

var tessel = require('tessel');
var pir = require('../').use(tessel.port['GPIO'].pin['G3']);

pir.on('ready', function (pir) {
  console.log('Ready and waiting...');
  pir.on('movement', function (time) {
    console.log('Something moved! Time ' + time);
  });
  pir.on('stillness', function (time) {
    console.log('All is still. Time ' + time);
  });
});

pir.on('error', function (err) {
  console.log(err);
});

Methods

# pir.read( [callback(data)] )
Reads the value of the pin: 1 for movement; 0 for stillness. Returns the value or outputs to callback.

Events

# pir.on( 'error', callback(error) )
Emitted on error connecting

# pir.on( 'ready', callback(err, pir) )
Emitted when the pir object is first initialized

# pir.on( 'movement', callback(time) )
Emitted when movement is first detected.

# pir.on( 'stillness', callback(time) )
Emitted at the onset of stillness.

# pir.on( 'change', callback(time, value) )
Emitted whenever the state changes. value is the pin.read value after the change.

Properties

# pir.movementtrue while movement detected; false while no movement detected

Licensing

Copyright Kelsey Breseman, Apache 2.0 Licensed.