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Board

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Rick Waldron edited this page Apr 26, 2015 · 61 revisions

The Board class constructs objects that represent the physical board itself. All device objects depend on an initialized and ready board object.

Johnny-Five (sans IO Plugin) has been tested on, but is not limited to, the following boards:

For non-Arduino based projects, a number of IO Plugins are available:

See also: Multi-Board Support

Parameters

  • options Optional object of themselves optional parameters.

    | Property | Type | Value/Description | Required | |---------------|------------------|-----------------------------------------|------------------------------------------------------|----------| | id | Number, String | Any. User definable identification | no | | port | String or object | eg. /dev/ttyAM0, COM1, new SerialPort(). Path or name of device port/COM or SerialPort object | no | | repl | Boolean | true, false. Set to false to disable REPL | no | | debug | Boolean | true, false. Set to false to disable debugging output. Defaults to true | no |

Shape

{ 
  io: A reference to the IO protocol layer.
  id: A user definable id value. Defaults to a generated uid.
  repl: A reference to the active REPL.
}

Component Initialization

To initialize control of a board, construct an instance of the Board class.

When connecting to a USB serial device, such as an Arduino, you do not need to specify the device path or COM port, Johnny-Five will determine which to connect to and connect automatically.

new five.Board();

You may optionally specify the port by providing it as a property of the options object parameter.

// OSX
new five.Board({ port: "/dev/tty.usbmodem****" });

// Linux
new five.Board({ port: "/dev/ttyUSB*" });

// Windows
new five.Board({ port: "COM*" });

* Denotes system specific enumeration value (ie. a number)

You can specify a SerialPort object by providing it as a property of the options object parameter:

var SerialPort = require("serialport").SerialPort;
var five = require("johnny-five");
var board = new five.Board({
  port: new SerialPort("COM4", {
    baudrate: 9600,
    buffersize: 1
  })
});

Usage

A basic, but complete example usage of the Board constructor:

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

board.on("ready", function() {
  /*
    Initialize pin 13, which 
    controls the built-in LED
  */
  var led = new five.Led(13);
  
  /*
    Injecting object into the REPL
    allow access while the program
    is running. 
    
    Try these in the REPL: 
    
    led.on();
    led.off();
    led.blink();

    (One at a time to see each action)
  */
  this.repl.inject({
    led: led
  });
});

API

  • repl This is a reference to the active REPL automatically created by the Board class. This object has an inject method that may be called as many times as desired:

    • repl.inject(object) Inject objects or values, from the program, into the REPL session.

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

board.on("ready", function() {
  // Initialize an LED directly in the REPL
  this.repl.inject({
    led: new five.Led(13)
  });  
});
/*
  From the terminal...

  $ node program.js
  1423012815316 Device(s) /dev/cu.usbmodem1421
  1423012818908 Connected /dev/cu.usbmodem1421
  1423012818908 Repl Initialized  
  >> led.on();
  >> led.off();
  
*/

  • pinMode(pin, mode) Set the mode of a specific pin, one of INPUT, OUTPUT, ANALOG, PWM, SERVO. Mode constants are exposed via the Pin class

    Mode Value Constant
    INPUT 0 Pin.INPUT
    OUTPUT 1 Pin.OUTPUT
    ANALOG 2 Pin.ANALOG
    PWM 3 Pin.PWM
    SERVO 4 Pin.SERVO 
    // Set a pin to INPUT mode
var five = require("johnny-five");
var board = new five.Board();

board.on("ready", function() {
  
  // pin mode constants are available on the Pin class
  this.pinMode(13, five.Pin.INPUT);
});

  • analogWrite(pin, value) Write an unsigned, 8-bit value (0-255) to a digital pin.

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

board.on("ready", function() {
  // Assuming an Led is attached to pin 9, 
  // this will turn it on at full brightness
  // PWM is the mode used to write ANALOG 
  // signals to a digital pin
  this.pinMode(9, five.Pin.PWM);
  this.analogWrite(9, 255);
});

  • analogRead(pin, handler(voltage)) Register a handler to be called whenever the board reports the voltage value (0-1023) of the specified analog pin.

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

board.on("ready", function() {
  // Assuming a sensor is attached to pin "A1"
  this.pinMode(1, five.Pin.ANALOG);
  this.analogRead(1, function(voltage) {
    console.log(voltage);
  });
});

  • digitalWrite(pin, value) Write a digital value (0 or 1) to a digital pin.

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

board.on("ready", function() {
  // Assuming an Led is attached to pin 13, this will turn it on
  this.pinMode(13, five.Pin.OUTPUT);
  this.digitalWrite(13, 1);
});

  • digitalRead(pin, handler(value)) Register a handler to be called whenever the board reports the value (0 or 1) of the specified digital pin.

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

board.on("ready", function() {
  // Assuming a button is attached to pin 9
  this.pinMode(9, five.Pin.INPUT);
  this.digitalRead(9, function(value) {
    console.log(value);
  });
});

    Note: digitalRead will only call its handler when the value of the pin changes.

  • i2cConfig([milliseconds]) This must be called prior to any I2C reads or writes. Optionally accepts a period in milliseconds to delay between read operations.

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

board.on("ready", function() {
  this.i2cConfig();
  // Safely interact with I2C components
});

  • i2cWrite(address, arrayOfBytes) Write an arrayOfBytes to the component at address.

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

board.on("ready", function() {
  this.i2cConfig();
  this.i2cWrite(0x01, [0x02, 0x03]);
});

  • i2cWrite(address, register, arrayOfBytes) Write an arrayOfBytes to the component at address, for a specific register.

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

board.on("ready", function() {
  this.i2cConfig();
  this.i2cWrite(0x01, 0x00, [0x02, 0x03]);
});

  • i2cWriteReg(address, register, byte) Write a single byte to the component at address, for a specific register.

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

board.on("ready", function() {
  this.i2cConfig();
  this.i2cWrite(0x01, 0x00, 0x7e);
});

  • i2cRead(address, bytesToRead, handler(arrayOfBytes)) Repeatedly read the specified number of bytes (bytesToRead) and call handler with the results as arrayOfBytes.

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

board.on("ready", function() {
  this.i2cConfig();
  this.i2cRead(0x01, 0x02, 6, function(bytes) {
    console.log("Bytes read: ", bytes);
  });
});

  • i2cRead(address, register, bytesToRead, handler(arrayOfBytes)) Repeatedly read the specified number of bytes (bytesToRead), starting at a specific register, and call handler with the results as arrayOfBytes.

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

board.on("ready", function() {
  this.i2cConfig();
  this.i2cRead(0x01, 0x00, 6, function(bytes) {
    console.log("Bytes read: ", bytes);
  });
});

  • i2cReadOnce(address, register, bytesToRead, handler(arrayOfBytes)) Read the specified number of bytes (bytesToRead), starting at a specific register, and call handler with the results as arrayOfBytes.

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

board.on("ready", function() {
  this.i2cConfig();
  this.i2cReadOnce(0x01, 0x02, 6, function(bytes) {
    console.log("Bytes read: ", bytes);
    console.log("Done!");
  });
});

  • i2cReadOnce(address, bytesToRead, handler) Read the specified number of bytes (bytesToRead) and call handler with the results as arrayOfBytes.

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

board.on("ready", function() {
  this.i2cConfig();
  this.i2cRead(0x01, 6, function(bytes) {
    console.log("Bytes read: ", bytes);
    console.log("Done!");
  });
});

  • servoWrite(pin, angle) Write an angle in degrees from 0-180 to a servo.

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

board.on("ready", function() {
  this.pinMode(9, five.Pin.SERVO);
  this.servoWrite(9, 90);
});

  • shiftOut(dataPin, clockPin, isBigEndian, value) Write a byte to dataPin, followed by toggling the clockPin. Understanding Big and Little Endian Byte Order

  • wait(milliseconds, handler()) Register a handler to be called once in another execution turn and after milliseconds has elapsed.

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

board.on("ready", function() {
  // Assuming an Led is attached to pin 13
  this.pinMode(13, five.Pin.OUTPUT);

  // Turn it on...
  this.digitalWrite(13, 1);

  this.wait(1000, function() {
    // Turn it off...
    this.digitalWrite(13, 0);
  });
});

  • loop(milliseconds, handler()) Register a handler to be called repeatedly, in another execution turn, every milliseconds period.

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

board.on("ready", function() {
  var byte;

  // Assuming an Led is attached to pin 13
  this.pinMode(13, five.Pin.OUTPUT);

  // Homemade blink
  this.loop(500, function() {
    this.digitalWrite(13, (byte ^= 0x01));
  });
});

Events

  • connect This event will emit once the program has "connected" to the board. This may be immediate, or after some amount of time, but is always asynchronous. For on-board execution, connect should emit as soon as possible, but asynchronously.

  • ready This event will emit after the connect event and only when the Board instance object has completed any hardware initialization that must take place before the program can operate. This process is asynchronous, and completion is signified to the program via a "ready" event. For on-board execution, ready should emit after connect.

Examples

The JavaScript Robotics Programming Framework

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