Accelerometer

The Accelerometer class constructs objects that represent a single Accelerometer sensor attached to the physical board.

Supported Accelerometers:

• Analog (Like the Tinkerkit 2/3-Axis Accelerometer)
• MPU6050 (I2C IMU)
• ADXL345 (I2C)
• ADXL335 (Analog)
• MMA7361 (Analog)

This list will continue to be updated as more Analog devices are confirmed.

Parameters

• General Options

Property Name	Type	Value(s)	Description	Default	Required
controller	string	ANALOG, MPU6050, ADXL345, ADXL335, MMA7361	The Name of the controller to use	"ANALOG"	no

• Analog Options (controller: "ANALOG")

Property Name	Type	Value(s)	Description	Default	Required
pins	Array of Strings	["A*"]	The String analog pins that X, Y, and Z (optional) are attached to	none	yes
sensitivity	Number	Varies by device	This value can be identified in the device's datasheet.	96 (Tinkerkit)	no
aref	Number	Voltage reference	This is the value of the VCC pin	5	no
zeroV	Number or Array	0-1023	The analog input when at rest, perpendicular to gravity. When an array, specifies the zeroV for the individual axes.	478	no
autoCalibrate	Boolean	true/false	Whether to auto-calibrate the `zeroV` values. The device must be initialized with X/Y axes perpendicular to the earth, and the Z axis pointing to the sky.	false	no

• MPU6050 Options (controller: "MPU6050")

Property Name	Type	Value(s)	Description	Default	Required
sensitivity	Number	16 bit value	The sensitivity for the +- 250 setting of this device	16384	no

• MMA7361 Options (controller: "MMA7361")

Property Name	Type	Value(s)	Description	Default	Required
sleepPin	Number or String	Digital Pin Address	The digital pin that controls the sleep pin on the device. If you don't set this pin, you need to pull it up to Vcc with a 10k resistor.	null	no

Shape

{ 
  id: A user definable id value. Defaults to a generated uid
  zeroV: The current zeroV value (or values).  
          May be different from initial values if auto-calibrated.
  pins: The pins defined for X, Y, and Z.
  pitch: The pitch angle in degrees. READONLY
  roll: The roll angle in degrees. READONLY
  x: Value of x axis in G forces. READONLY
  y: Value of y axis in G forces. READONLY
  z: Value of z axis in G forces. READONLY
  acceleration: The magnitude of the acceleration in G forces. READONLY
  inclination: The incline of the device in degrees. READONLY
  orientation: The orientation of the device (-3, -2, -1, 1, 2, 3). READONLY 
}

Controller Initializations

// Create an analog Accelerometer object:
// 
//   - attach X and Y to "A0" and "A1" respectively
//
var accelerometer = new five.Accelerometer({
  pins: ["A0", "A1"],
  sensitivity: 96, // optional
  aref: 5,         // optional
  zeroV: 478       // optional
});

// Create an MPU-6050 Accelerometer object:
//
//  - attach SDA and SCL to the I2C pins on your board (A4 and A5 for the Uno)
//  - specify the MPU6050 controller
var accelerometer = new five.Accelerometer({
  controller: "MPU6050",
  sensitivity: 16384 // optional
});

// Create an ADXL345 Accelerometer object:
//
//  - attach SDA and SCL to the I2C pins on your board (A4 and A5 for the Uno)
//  - specify the ADXL345 controller
var accelerometer = new five.Accelerometer({
  controller: "ADXL345"
});

// Create an ADXL335 Accelerometer object:
//
//  - attach Xout, Yout and Zout to A0, A1, A2
//  - specify the ADXL335 controller
var accelerometer = new five.Accelerometer({
  controller: "ADXL335",
  pins: ["A0", "A1", "A2"]
});

// Create an MMA7361 Accelerometer object:
//
// - attach Xo, Yo, and Zo to A0, A1, A2
// - specify the MMA7361 controller
// - optionally, specify the sleepPin
// - optionally, set it to auto-calibrate
// - optionally, set the zeroV values.  This can be done when retrieving them after an autoCalibrate
var accelerometer = new five.Accelerometer({
    controller: "MMA7361",
    pins: ["A0", "A1", "A2"],
    sleepPin: 13,
    autoCalibrate: true,
    zeroV: [320, 365, 295] // override the zeroV values if you know what they are from a previous autoCalibrate
  });

Usage

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

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

  var accelerometer = new five.Accelerometer({
    pins: ["A0", "A1"]
  });

  accelerometer.on("change", function(err, data) {
    console.log("X: %d", this.x);
    console.log("Y: %d", this.y);
  });
});

API

• hasAxis(name) Does the device support the axis?

if (accelerometer.hasAxis("z")) {
  console.log(accelerometer.z)
}

• enable() Enable the device and events (enabled by default). For devices that can be put to sleep (like the MMA7361), wake it up.

accelerometer.enable();

• disable() Disable the device and events. For devices that can be put to sleep (like the MMA7361), put it to sleep.

accelerometer.disable();

Events

• change The "change" event is emitted whenever the value of the accelerometer changes more then the threshold value allows.

• data The "data" event is fired as frequently as the user defined freq will allow in milliseconds. ("data" replaced the "read" event)

Examples

• Tinkerkit Accelerometer
• MPU6050 Accelerometer
• MMA7361 Accelerometer
• Accelerometer
• Accelerometer Pan and Tilt