File: src/io/DCMotor.js

 /**
  * Based on DCMotor.as originally written in as3.
  * Copyright (c) the Funnel development team
  * http://www.funnel.cc
  *
  * Ported to JavaScript by Jeff Hoefs
  * Copyright (c) 2011-2012 Jeff Hoefs <soundanalogous@gmail.com>
  *
  * Released under the MIT license. See LICENSE file for details.
  */

 JSUTILS.namespace('BO.io.DCMotor');

 BO.io.DCMotor = (function() {

   var DCMotor;

   // Dependencies
   var Pin = BO.Pin;

   /**
    * Creates an interface to an H-bridge to control the direction of rotation
    * of a motor shaft. You can rotate forward (clockwise), reverse or apply a
    * brake. See [Breakout/examples/actuators/dcmotor.html](https://github.com/soundanalogous/Breakout/blob/master/examples/actuators/dcmotor.html) for an example
    * application.
    *
    * <p>Tested successfully with the following H-bridge: SN754410<br>
    * Should also be compatible with the following:<br>
    * SN754410<br>
    * L293NE<br>
    * TA7291P<br>
    * TB6612FNG<br>
    * BD621F</p>
    *
    * @class DCMotor
    * @constructor
    * @param {IOBoard} board A reference to the IOBoard instance that the
    * servo is attached to.
    * @param {Pin} forwardPin A reference to the Pin connected to the forward
    * control of the H-bridge.
    * @param {Pin} reversePin A reference to the Pin connected to the reverse
    * control of the H-bridge.
    * @param {Pin} pwmPin A reference to the Pin connected to the pwm control
    * of the H-bridge.
    * @param {Number} minVoltage The minimum voltage (default = 1).
    * @param {Number} maxVoltage The maximum voltage (default = 9).
    * @param {Number} supplyVoltage The supply voltage (default = 9).
    */
   DCMotor = function(board, forwardPin, reversePin, pwmPin, minVoltage, maxVoltage, supplyVoltage) {
     "use strict";

     this.name = "DCMotor";

     minVoltage = minVoltage || 1;
     maxVoltage = maxVoltage || 9;
     supplyVoltage = supplyVoltage || 9;
     if (pwmPin === undefined) {
       pwmPin = null;
     }

     this._value = 0;
     this._offset = 0;
     this._range = 0;

     this._forwardPin = forwardPin;
     this._reversePin = reversePin;
     this._pwmPin = pwmPin;

     if (this._pwmPin !== null) {
       if (this._pwmPin.getCapabilities()[Pin.PWM]) {
         board.setDigitalPinMode(this._pwmPin.number, Pin.PWM);
       } else {
         console.log("warning: PWM is not available for the PWM pin");
         board.setDigitalPinMode(this._pwmPin.number, Pin.DOUT);
       }
     }

     if (this._forwardPin.getCapabilities()[Pin.PWM]) {
       board.setDigitalPinMode(this._forwardPin.number, Pin.PWM);
     } else {
       console.log("warning: PWM is not available for the forward pin");
       board.setDigitalPinMode(this._forwardPin.number, Pin.DOUT);
     }

     if (this._reversePin.getCapabilities()[Pin.PWM]) {
       board.setDigitalPinMode(this._reversePin.number, Pin.PWM);
     } else {
       console.log("warning: PWM is not available for the reverse pin");
       board.setDigitalPinMode(this._reversePin.number, Pin.DOUT);
     }

     this._offset = (minVoltage / supplyVoltage);
     this._range = (maxVoltage - minVoltage) / supplyVoltage;

     this.despin(false);

   };

   DCMotor.prototype = {

     constructor: DCMotor,

     /**
      * The value of the motor speed (-1.0 to 1.0). A speed of zero stops
      * the motor.
      * @property value
      * @type Number
      */
     set value(val) {
       this._value = Math.max(-1, Math.min(1, val));

       if (val > 0) {
         this.forward(this._value);
       } else if (val < 0) {
         this.reverse(-this._value);
       } else {
         this.despin();
       }
     },
     get value() {
       return this._value;
     },

     /**
      * @method despin
      * @param {Boolean} useBrake Default = true
      */
     despin: function(useBrake) {
       if (useBrake === undefined) {
         useBrake = true;
       }

       if (useBrake) {
         if (this._pwmPin === null) {
           this._forwardPin.value = 1;
           this._reversePin.value = 1;
         } else {
           this._forwardPin.value = 1;
           this._reversePin.value = 1;
           this._pwmPin.value = 1;
         }
       } else {
         if (this._pwmPin === null) {
           this._forwardPin.value = 0;
           this._reversePin.value = 0;
         } else {
           this._forwardPin.value = 0;
           this._reversePin.value = 0;
           this._pwmPin.value = 0;
         }
       }
       this._value = 0;
     },

     /**
      * @method forward
      * @param {Number} val The new voltage to set (0.0 to 1.0)
      */
     forward: function(val) {
       val = val || 1;
       this._value = Math.max(0, Math.min(1, val));

       if (this._pwmPin === null) {
         this._forwardPin.value = Math.max(0, Math.min(1, this._value * this._range + this._offset));
         this._reversePin.value = 0;
       } else {
         this._forwardPin.value = 1;
         this._reversePin.value = 0;
         this._pwmPin.value = Math.max(0, Math.min(1, this._value * this._range + this._offset));
       }
     },

     /**
      * @method reverse
      * @param {Number} val The new voltage to set (-1.0 to 0.0)
      */
     reverse: function(val) {
       val = val || 1;
       this._value = Math.max(0, Math.min(1, val)) * -1;

       if (this._pwmPin === null) {
         this._forwardPin.value = 0;
         this._reversePin.value = Math.max(0, Math.min(1, (this._value * this._range) * -1 + this._offset));
       } else {
         this._forwardPin.value = 0;
         this._reversePin.value = 1;
         this._pwmPin.value = Math.max(0, Math.min(1, (this._value * this._range) * -1 + this._offset));
       }
     }

   };

   return DCMotor;

 }());