johnny-five/lib/joystick.js

var Board = require("./board");
var Emitter = require("events").EventEmitter;
var util = require("util");
var Fn = require("./fn");
var priv = new Map();
var axes = ["x", "y"];

function Multiplexer(options) {
  this.pins = options.pins;
  this.io = options.io;

  // Setup these "analog" pins as digital output.
  this.io.pinMode(this.pins[0], this.io.MODES.OUTPUT);
  this.io.pinMode(this.pins[1], this.io.MODES.OUTPUT);
  this.io.pinMode(this.pins[2], this.io.MODES.OUTPUT);
  this.io.pinMode(this.pins[3], this.io.MODES.OUTPUT);
}

Multiplexer.prototype.select = function(channel) {
  this.io.digitalWrite(this.pins[0], channel & 1 ? this.io.HIGH : this.io.LOW);
  this.io.digitalWrite(this.pins[1], channel & 2 ? this.io.HIGH : this.io.LOW);
  this.io.digitalWrite(this.pins[2], channel & 4 ? this.io.HIGH : this.io.LOW);
  this.io.digitalWrite(this.pins[3], channel & 8 ? this.io.HIGH : this.io.LOW);
};

var Controllers = {
  ANALOG: {
    initialize: {
      value: function(opts, dataHandler) {
        var axisValues = {
          x: null,
          y: null
        };

        opts.pins.forEach(function(pin, index) {
          this.io.pinMode(pin, this.io.MODES.ANALOG);
          this.io.analogRead(pin, function(value) {
            axisValues[axes[index]] = value;

            if (axisValues.x !== null && axisValues.y !== null) {
              dataHandler({
                x: axisValues.x,
                y: axisValues.y
              });

              axisValues.x = null;
              axisValues.y = null;
            }
          }.bind(this));
        }, this);
      }
    },
    toAxis: {
      value: function(raw, axis) {
        var state = priv.get(this);
        return Fn.constrain(Fn.fscale(raw - state[axis].zeroV, -511, 511, -1, 1), -1, 1);
      }
    }
  },
  ESPLORA: {
    initialize: {
      value: function(opts, dataHandler) {
        // References:
        //
        // https://github.com/arduino/Arduino/blob/master/libraries/Esplora/src/Esplora.h
        // https://github.com/arduino/Arduino/blob/master/libraries/Esplora/src/Esplora.cpp
        //
        var multiplexer = new Multiplexer({
          // Since Multiplexer uses digitalWrite,
          // we have to send the analog pin numbers
          // in their "digital" pin order form.
          pins: [18, 19, 20, 21],
          io: this.io
        });
        var channels = [11, 12];
        var index = 1;
        var axisValues = {
          x: null,
          y: null
        };

        this.io.pinMode(4, this.io.MODES.ANALOG);

        var handler = function(value) {
          axisValues[axes[index]] = value;

          if (axisValues.x !== null && axisValues.y !== null) {
            dataHandler({
              x: axisValues.x,
              y: axisValues.y
            });

            axisValues.x = null;
            axisValues.y = null;
          }

          // Remove this handler to all the multiplexer
          // to setup the next pin for the next read.
          this.io.removeListener("analog-read-4", handler);

          setTimeout(read, 10);
        }.bind(this);

        var read = function() {
          multiplexer.select(channels[index ^= 1]);
          this.io.analogRead(4, handler);
        }.bind(this);

        read();
      }
    },
    toAxis: {
      value: function(raw, axis) {
        var state = priv.get(this);
        return Fn.constrain(Fn.fscale(raw - state[axis].zeroV, -511, 511, -1, 1), -1, 1);
      }
    }
  }
};


/**
 * Joystick
 * @constructor
 *
 * five.Joystick([ x, y[, z] ]);
 *
 * five.Joystick({
 *   pins: [ x, y[, z] ]
 *   freq: ms
 * });
 *
 *
 * @param {Object} opts [description]
 *
 */
function Joystick(opts) {
  if (!(this instanceof Joystick)) {
    return new Joystick(opts);
  }

  var controller = null;

  var state = {
    x: {
      invert: false,
      value: 0,
      previous: 0,
      zeroV: 0,
      calibrated: false
    },
    y: {
      invert: false,
      value: 0,
      previous: 0,
      zeroV: 0,
      calibrated: false
    }
  };

  Board.Component.call(
    this, opts = Board.Options(opts)
  );

  if (opts.controller && typeof opts.controller === "string") {
    controller = Controllers[opts.controller.toUpperCase()];
  } else {
    controller = opts.controller;
  }

  if (controller == null) {
    controller = Controllers.ANALOG;
  }

  Board.Controller.call(this, controller, opts);

  if (!this.toAxis) {
    this.toAxis = opts.toAxis || function(raw) {
      return raw;
    };
  }

  state.x.zeroV = opts.zeroV === undefined ? 0 : (opts.zeroV.x || 0);
  state.y.zeroV = opts.zeroV === undefined ? 0 : (opts.zeroV.y || 0);

  state.x.invert = opts.invertX || opts.invert || false;
  state.y.invert = opts.invertY || opts.invert || false;

  priv.set(this, state);

  if (typeof this.initialize === "function") {
    this.initialize(opts, function(data) {
      var isChange = false;
      var computed = {
        x: null,
        y: null
      };

      Object.keys(data).forEach(function(axis) {
        var value = data[axis];
        var sensor = state[axis];

        // Set the internal ADC reading value...
        sensor.value = value;

        if (!state[axis].calibrated) {
          state[axis].calibrated = true;
          state[axis].zeroV = value;
          isChange = true;
        }

        // ... Get the computed axis value.
        computed[axis] = this[axis];

        var absAxis = Math.abs(computed[axis]);
        var absPAxis = Math.abs(sensor.previous);

        if ((absAxis < absPAxis) ||
          (absAxis > absPAxis)) {
          isChange = true;
        }

        sensor.previous = computed[axis];
      }, this);

      this.emit("data", {
        x: computed.x,
        y: computed.y
      });

      if (isChange) {
        this.emit("change", {
          x: computed.x,
          y: computed.y
        });
      }
    }.bind(this));
  }

  Object.defineProperties(this, {
    x: {
      get: function() {
        return this.toAxis(state.x.value, "x") * (state.x.invert ? -1 : 1);
      }
    },
    y: {
      get: function() {
        return this.toAxis(state.y.value, "y") * (state.y.invert ? -1 : 1);
      }
    }
  });
}

util.inherits(Joystick, Emitter);

/* istanbul ignore else */
if (!!process.env.IS_TEST_MODE) {
  Joystick.Controllers = Controllers;
  Joystick.purge = function() {
    priv.clear();
  };
}

module.exports = Joystick;