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Nobleのコードをasync/awaitで記述するメモ

Last updated at Posted at 2019-02-14

公式のサンプルなどがコールバック地獄で結構辛いので、util.promisify()を使ってなんとかできないかと思うのですが、そこまで上手くはいかないです。

bluebirdのpromisifyAllを使うといい感じに出来ました。

参考: Nobleをbluebirdで更にスッキリさせる

npm i bluebird
'use strict';

const noble = require('noble');
const Promise = require('bluebird'); //Promisifyで利用

const peripheralUUID = 'xxxxxxxxxxxxxxx'; //各自書き換え
const serviceUUIDs = ['180d']; //各自書き換え
const characteristicUUIDs = ['2a39']; //各自書き換え

//discovered BLE device
const discovered = async (peripheral) => {
    // if(peripheral.advertisement.localName !== 'Heart Rate') return;
    if(peripheral.uuid !== peripheralUUID) return;
    noble.stopScanning(); //スキャン停止
    console.log(`[Found Device] ${peripheral.advertisement.localName}(${peripheral.uuid}) RSSI${peripheral.rssi}`);

    /**
     * ペリフェラルへのアクセス
     */
    const p = Promise.promisifyAll(peripheral); //Promisify
    await p.connectAsync();
    console.log(`[Connect Device] coneccting service & characteristic......`);
    
    /**
     * サービス&キャラクタリスティックへのアクセス
     */
    const services = await p.discoverSomeServicesAndCharacteristicsAsync(serviceUUIDs,characteristicUUIDs);
    const characteristic = services.reduce((pre, current) => (current.uuid === serviceUUIDs[0]))
                            .characteristics
                            .reduce((pre, current) => (current.uuid === characteristicUUIDs[0]));
    const c = Promise.promisifyAll(characteristic); //Promisify
    console.log(`[Connect characteristic] coneccting characteristic's Data......`);

    /**
     * キャラクタリスティックのデータにアクセス
     */
    const toggle = async () => {
        try {
            const data = await c.readAsync();
            let state = data.readUInt8(0);
            console.log(state);
            state = (state === 0) ? 1 : 0;
            await c.writeAsync(new Buffer.from([state]), true);
            setTimeout(() => toggle(), 1000); //1秒ごとに実行
        } catch (error) {
            console.log(error);        
        }
    }
    toggle();
}

//BLE scan start
const scanStart = () => {
    if(noble.state !== 'poweredOn'){
        noble.on('stateChange', scanStart)
    }else{
        noble.startScanning();
        noble.on('discover', discovered); //Discover
    }
}
scanStart();
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