boost-movehub/src/peripherals/Peripheral.js

Connects with your Lego Boost Movehub vie Bluetooth Low Energy (BLE).

const { EventEmitter } = require("events");

const PortInputFormatSetup = require("../messages/PortInputFormatSetup");

const DEFAULT_OPTIONS = {
  logger: {}
};

/**
 * This is the base class for all the peripherals of an Movehub.
 */
class Peripheral extends EventEmitter {
  /**
   * @param {Number} ioType Peripheral Device Type ID (One of `Peripheral.DEV_*`)
   * @param {Number} portId Port ID this peripheral is connected to
   * @param {object} [options.ioMembers] If this has severeal members, it is a virtual device
   * @param {object} [options.logger]
   */
  constructor(ioType, portId, options = DEFAULT_OPTIONS) {
    super();
    this.displayName = "Peripheral";
    this.subscriptionActive = false;
    this.ioType = ioType;
    this.portId = portId;
    this.logger = options.logger || {};
    this.isVirtualDevice = options.ioMembers && options.ioMembers.length > 1;
    this.lastValue = null;
  }

  _log(type, ...message) {
    this.logger[type] &&
      this.logger[type](
        `[${this.displayName}]`,
        new Date().toISOString(),
        ...message
      );
  }

  /**
   * Creates a message that starts subscribing to updates.
   *
   * @param {number} [mode] Mode in which updates should come in (One of `<YourPeripheral>.MODE_*`)
   */
  subscribe(mode = this.defaultMode) {
    return PortInputFormatSetup.build(this.portId, { mode });
  }

  /**
   * Disable from all updates from hub.
   */
  unsubscribe() {
    return PortInputFormatSetup.build(this.portId, {
      notificationEnabled: PortInputFormatSetup.DISABLE_NOTIFICATONS
    });
  }

  /**
   * Handle acknowledge message for prior subscribe or unsubscribe.
   *
   * @param {PortInputFormat} msg
   */
  receiveSubscriptionAck(msg) {
    this.subscriptionActive = msg.notificationEnabled;
    this.emit(msg.notificationEnabled ? "subscribed" : "unsubscribed");
    this._log("debug", "ack", msg.toString());
    this.mode = msg.mode;
  }

  /**
   * Sets the value received by the Hub.
   *
   * @param {number} value
   */
  setValue(value) {
    this.lastValue = value;
    /**
     * Fires when a new value is set on a Peripheral.
     * @event Peripheral#value
     * @param {number} value
     */
    this.emit("value", value);
  }

  /**
   * Async method to get the current value. If no value was received yet,
   * it waits for a value to be received before resolving.
   */
  async getValueAsync() {
    if (this.lastValue !== null) {
      return this.lastValue;
    }
    return new Promise(resolve => {
      this.once("value", resolve);
    });
  }
}

/**
 * Defined in https://lego.github.io/lego-ble-wireless-protocol-docs/index.html#io-type-id
 */
Peripheral.DEV_MOTOR = 0x0001; // 1
Peripheral.DEV_SYSTEM_TRAIN_MOTOR = 0x0002; // 2
Peripheral.DEV_BUTTON = 0x0005; // 5
Peripheral.DEV_LED_LIGHT = 0x0008; // 8
Peripheral.DEV_VOLTAGE = 0x0014; // 20
Peripheral.DEV_CURRENT = 0x0015; // 21
Peripheral.DEV_PIEZO_SOUND = 0x0016; // 22
Peripheral.DEV_RGB_LIGHT = 0x0017; // 23
Peripheral.DEV_TILT_EXTERNAL = 0x0022; // 34
Peripheral.DEV_MOTION_SENSOR = 0x0023; // 35
Peripheral.DEV_VISION_SENSOR = 0x0025; // 37
Peripheral.DEV_MOTOR_EXTERNAL_TACHO = 0x0026; // 38
Peripheral.DEV_MOTOR_INTERNAL_TACHO = 0x0027; // 39
Peripheral.DEV_TILT_INTERNAL = 0x0028; // 40

module.exports = Peripheral;