Rick Waldron edited this page Feb 20, 2018 · 26 revisions

The IMU class constructs objects that represent a single IMU module attached to the physical board. An IMU is an Inertial Measurement Unit. IMUs come in all shapes and DOFs (Degrees of Freedom). They are often made up of several components like Accelerometers, Gyros, Thermometer, and Compass/Magnetometers.

Supported modules:

This list will continue to be updated as more component support is implemented.

Parameters

  • General Options

    Property Type Value/Description Default Required
    controller string BNO055, LSM303C, MPU6050. The Name of the controller to use "MPU6050" no
  • MPU6050 Options(controller: "MPU6050")

    Property Type Value/Description Default Required
    address Number 8-bit value. The address of the component (can be switched via ADO pin) 0x68 no

Shape

Some of these properties may or may not exist depending on whether the IMU supports it.

Property Name Description Read Only
accelerometer An instance of Accelerometer class. Yes
compass An instance of Compass class. Yes
gyro An instance of Gyro class. Yes
orientation An instance of Orientiation class. Yes
thermometer An instance of Thermometer class. Yes

Component Initialization

MPU6050

// Create an MPU-6050 IMU object:
//
//  - attach SDA and SCL to the I2C pins on your board (A4 and A5 for the Uno)
//  - specify the MPU6050 controller
new five.IMU({
  controller: "MPU6050",
  address: 0x68, // optional
  freq: 100      // optional
});

imu-mpu6050.png

BNO055

// Create an BNO055 IMU object:
//
//  - attach SDA and SCL to the I2C pins on your board (A4 and A5 for the Uno)
//  - specify the BNO055 controller
new five.IMU({
  controller: "BNO055"
});

imu-bno055.png

LSM303C

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

imu-lsm303c.png

Usage

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

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

  var accelerometer = new five.IMU({
    controller: "MPU6050"
  });

  accelerometer.on("data", function(err, data) {
    console.log("Accelerometer: %d, %d, %d", this.accelerometer.x, this.accelerometer.z, this.accelerometer.z);
    console.log("Gyro: %d, %d, %d", this.gyro.x, this.gyro.z, this.gyro.z);
    console.log("Temperature: %d", this.temperature.celsius);
  });
});

API

The IMU does not have an explicit API. Refer to the individual components for their APIs

Events

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

  • change The "change" event is fired whenever a corresponding "change" is fired from a component.

  • calibrated The "calibrated" event is fired whenever a corresponding "calibrated" is fired from a component.

Examples

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