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 component support is implemented.

Parameters

• General Options

  Property	Type	Value/Description	Default	Required
  controller	string	ANALOG, MPU6050, ADXL345, ADXL335, MMA7361. The Name of the controller to use	“ANALOG”	no

• Analog Options (controller: "ANALOG")

  Property	Type	Value/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	Type	Value/Description	Default	Required
  sensitivity	Number	16 bit value. The sensitivity for the +- 250 setting of this device	16384	no

• MMA7361 Options (controller: "MMA7361")

  Property	Type	Value/Description	Default	Required
  sleepPin	Number or String	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

Property Name	Description	Read Only
id	A user definable id value. Defaults to a generated uid	No
zeroV	The current zeroV value (or values). May be different from initial values if auto-calibrated.	No
pins	The pins defined for X, Y, and Z.	No
pitch	The pitch angle in degrees.	Yes
roll	The roll angle in degrees.	Yes
x	Value of x axis in G forces.	Yes
y	Value of y axis in G forces.	Yes
z	Value of z axis in G forces.	Yes
acceleration	The magnitude of the acceleration in G forces.	Yes
inclination	The incline of the device in degrees.	Yes
orientation	The orientation of the device (-3, -2, -1, 1, 2, 3).	Yes

Component Initialization

Analog

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

MPU6050

// 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
new five.Accelerometer({
  controller: "MPU6050",
  sensitivity: 16384 // optional
});

ADXL345

// 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
new five.Accelerometer({
  controller: "ADXL345"
});

ADXL335

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

MMA7361

// 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
new five.Accelerometer({
  controller: "MMA7361",
  pins: ["A0", "A1", "A2"],
  sleepPin: 13,
  autoCalibrate: true,
  // override the zeroV values if you know what 
  // they are from a previous autoCalibrate
  zeroV: [320, 365, 295] 
});

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() {
    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 any reading changes.

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

Examples

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