蓝牙低功耗当外设发送“指示”时订阅特征使用贵族

问题描述

我正在尝试使用 noble(https://github.com/abandonware/noble) BLE 读取我的血压值。 服务是1810，特征是2a35，但是buffer是空的。属性为：['指示']

我知道我必须订阅才能读取缓冲区，但我不知道该怎么做。有人可以帮忙吗？ 我使用此代码：

const noble = require('@abandonware/noble');


noble.on('stateChange',async (state) => {
    if (state === 'poweredOn') {
        console.log('Scanning');
        await noble.startScanningAsync([],false);
    } else {
        noble.stopScanning();
    }
});

noble.on('discover',peripheral => {
    // connect to the first peripheral that is scanned
    noble.stopScanning();
    const name = peripheral.advertisement.localName;
    console.log(`Connecting to '${name}' ${peripheral.id}`);
    connectAndSetUp(peripheral);
});

function connectAndSetUp(peripheral) {
    peripheral.connect(error => {
        console.log('Connected to',peripheral.id);

        // specify the services and characteristics to discover
        const serviceUUIDs = ['1810'];
        const characteristicUUIDs = ['2a35'];

        peripheral.discoverSomeServicesAndCharacteristics(
            serviceUUIDs,characteristicUUIDs,onServicesAndCharacteristicsDiscovered
        );
    });

    peripheral.on('disconnect',() => console.log('disconnected'));
}

function onServicesAndCharacteristicsDiscovered(error,services,characteristics) {
    console.log('Discovered services and characteristics');
    const echoCharacteristic = characteristics[0];
    console.log(echoCharacteristic);

    // console.log( echoCharacteristic.read());
   
    // data callback receives notifications
    echoCharacteristic.on('data',(data,isNotification) => {
        console.log(`Received: "${data}"`);
    });

    // echoCharacteristic.once('data',data => console.log("oii "+data));
    // subscribe to be notified whenever the peripheral update the characteristic
     echoCharacteristic.subscribe( (error) => {
        if (error) {
            console.error('Error subscribing to echoCharacteristic');
        } else {
            // console.log( echoCharacteristic.Buffer);
            console.log('Subscribed for echoCharacteristic notifications');
        }
    });
 }
    

解决方法

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