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Board

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Rick Waldron edited this page Apr 24, 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(s) Description Required
    id Number, String Any User definable identification no
    port String or object "/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

Shape

{ 
  ready: A boolean value that indicates the readiness of the physical board
  io: A reference to the IO protocol layer.
  id: A user definable id value. Defaults to a generated uid
  pins: An array of all pin capabilities objects
  port: A string value of the device path or COM address
}

Component Initialization

The easiest way to initialize a board object is to call the Board constructor function with new. Don't worry about knowing your device's path or COM port, Johnny-Five will figure out which USB the board is plugged into and connect to that automatically.

new five.Board();

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

new five.Board({ port: "/dev/tty.usbmodemNNNN" });

or

new five.Board({ port: "COM1" });

or 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() {

  // Create an Led on pin 13
  var led = new five.Led(13);

  // Strobe the pin on/off, defaults to 100ms phases
  led.strobe();

});

API

  • repl This is a property of the board object that represents the automatically generated REPL that's created when a Johnny-Five program is executed. 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 object that can be controlled from the REPL session
  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  
  >> 
  (Since the led object is available here...)
  >> 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 analog 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);
  });
});

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

  • wait(ms, handler()) Register a handler to be called once in another execution turn and after the amount of time specified in milliseconds has passed.

    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(ms, handler()) Register a handler to be called repeatedly in another execution turn, every time the specified milliseconds has lapsed.

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

Events

  • connect This event will be emitted once the program has "connected" to the board. This may be immediate, or after some amount of time, but is always asynchronous.

  • ready This event will be emitted 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.

Examples

The JavaScript Robotics Programming Framework

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