The markdown for the Johnny-Five wiki to describe the Reflectance Array

ir.reflectance.array.md

The IR.Reflect.Array class constructs an array of analog (digital arrays are not currently supported) reflectance sensors like the QTR-8A from Pololu.

Parameters

• pins An array Numbers or Strings for the analog sensor pins.

• emitter The pin where the emitter LED is attached. For these arrays, there is one pin that controls all of the emitters.

var eyes = new five.Sensor({
  emitter: 13,
  pins: ["A0", "A1", "A2", "A3", "A4", "A5"]
});

• options An object of property parameters.

Property Name	Type	Value(s)	Description	Required
pins	Array of Number, String	["A0", "I1", 5] (Any pin on board)	The pins that the sensors are connected to	yes
emitter	Number, String	"A0", 13 (Any pin on board)	The pin that the light emitter is connected to	yes
freq	Number	Milliseconds	The frequency in ms of data events. Defaults to 25ms	no

```js

Shape

{
  id: A user definable id value. Defaults to a generated uid
  pins: The pin addresses that the sensors are attached to

  isOn: Are the emitters on? READONLY
  isCalibrated: Does the array have calibration data? READONLY
  isOnLine: Is the array currently tracking a line? READONLY, isCalibrated===true
  sensors: An array of sensor objects that represent each sensor in the array. READONLY
  calibration: The current calibration data. READONLY
  raw: An array of raw values from all the sensors. READONLY
  values: If calibrated, an array of calibrated values (between 0 and 1000).  If not calibrated, raw data (between 0 and 1023). READONLY
  line: If calibrated, a value between 0 and (n-1)*1000+1. For example, 6 sensors will have a line between 0 and 5001. READONLY
}

Usage

var five = require("johnny-five"),
    board = new five.Board();

board.on("ready", function() {

  // Create a new `reflectance` hardware instance.
  var eyes = new five.IR.Reflect.Array({
    emitter: 13,
    pins: ["A0", "A1", "A2"], // any number of pins
    freq: 25
  });

  eyes.on('data', function(err, rawValues) {
    console.log( "Raw Values: ", rawValues );
  });

  eyes.on('line', function(err, lineValue) {
    console.log( "Line Position: ", lineValue);
  });

  eyes.enable();
});

API

• enable() Turn the light emitters on.

var eyes = new five.Sensor({
  emitter: 13,
  pins: ["A0", "A1"]
});

eyes.enable();

• disable() turn the light emitters off

var eyes = new five.Sensor({
  emitter: 13,
  pins: ["A0", "A1"]
});

eyes.disable();

• calibrate() Read all of the sensors and store the min/max values. Used to calculate calibrated values and line values. You should call calibrate() multiple times.

var eyes = new five.Sensor({
  emitter: 13,
  pins: ["A0", "A1"]
});

for(var i=0; i<100; i++) {
  eyes.calibrate();
}

• calibrateUntil(predicate) A convenience function that will call calibrate until a predicate function returns true. This allows you to decide when calibration is done. This trigger may be user input, time, or execution count. You decide.

var eyes = new five.Sensor({
  emitter: 13,
  pins: ["A0", "A1"]
});

var calibrating = true;
eyes.calibrateUntil(function() {
  return !calibrating;
});

setTimeout(function() { calibrating = false; }, 1000 ); // calibrate for one second

• loadCalibration(calibration) Prime the array with calibration data. This allows you to load calibration data from a file. You can get it from the device using the calibration after it has been calibrated.

var eyes = new five.Sensor({
  emitter: 13,
  pins: ["A0", "A1"]
});

eyes.loadCalibration({
  min: [37, 39],
  max: [1010, 1015]
});

Events

• data The "data" event is fired as frequently as the user defined freq will allow in milliseconds. It includes an array of the RAW data from the sensors.

• calibratedData The "calibratedData" event is fired as frequently as the user defined freq will allow in milliseconds. It also requires that the device has been calibrated. It includes an array of calibrated values between 0 and 1000.

• line The "line" event is fired as frequently as the user defined freq will allow in milliseconds. It also requires that the devide has been calibrated. It is a single value between 0 and (n-1)*1000+1. An array with 6 sensors will yield a value between 0 and 5001.