Accelerometer

Rick Waldron edited this page Feb 20, 2018 · 47 revisions

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

Supported Accelerometers:

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, LSM303C. 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

Simplified array of X and Y axis pins, all defaults:

new five.Accelerometer(["A0", "A1"]);

Options object with pins property, array of X and Y axis pins, all defaults:

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

Options object with pins property, array of X and Y axis pins:

new five.Accelerometer({
  pins: ["A0", "A1"],
  sensitivity: 96, // optional
  aref: 5,         // optional
  zeroV: 478       // optional
});
// 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
});

LIS344AL

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
});

MPU6050

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"
});

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"]
});

ADXL335

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]
});

MMA7361

LSM303C

// Create an LSM303C Accelerometer object:
//
//  - attach SDA and SCL to the I2C pins on your board (A4 and A5 for the Uno)
//  - specify the LSM303C controller
new five.Accelerometer({
  controller: "LSM303C"
});

imu-lsm303c.png

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 measurements can be reported.

Examples

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