"Unable to connect to device" with bluetoothSerial.connect()

[JeremDlcn]

I made an ionic app with a connection between a Android phone and a HC-05 on an Arduino Uno. When i use the method .connect() with a .subscribe() in order to connect the device or catch error, the only error that i console.log is "Unable to connect to device".

Is there any way to know more about my error because a message with "unable to connect" don't help me to resolve my problem Thanks.

import { Component } from '@angular/core';
import { BluetoothSerial } from '@ionic-native/bluetooth-serial/ngx';
import { AlertController, ToastController } from '@ionic/angular';

@Component({
  selector: 'app-home',
  templateUrl: 'home.page.html',
  styleUrls: ['home.page.scss'],
})
export class HomePage {
  pairedList: pairedlist;
  listToggle: boolean = false;
  pairedDeviceID: number = 0;
  dataSend: string = "";

  constructor(private alertCtrl: AlertController, private bluetoothSerial: BluetoothSerial, private toastCtrl: ToastController) {
    this.checkBluetoothEnabled();
  }

  checkBluetoothEnabled() {
    this.bluetoothSerial.isEnabled().then(success => {
      this.listPairedDevices();
    }, error => {
      this.showError("Please Enable Bluetooth")
    });
  }

  listPairedDevices() {
    this.bluetoothSerial.list().then(success => {
      this.pairedList = success;
      this.listToggle = true;
    }, error => {
      this.showError("Please Enable Bluetooth")
      this.listToggle = false;
    });
  }

  selectDevice() {
    let connectedDevice = this.pairedList[this.pairedDeviceID];
    if (!connectedDevice.address) {
      this.showError('Select Paired Device to connect');
      return;
    }
    let address = connectedDevice.address;
    let name = connectedDevice.name;
    this.connection(address);
  }

  connection(address: string) {
    // Attempt to connect device with specified address, call app.deviceConnected if success
    this.bluetoothSerial.connect(address).subscribe(success => {
      this.deviceConnected();
      this.showToast("Successfully Connected");
    }, error => {
      console.log("Connection Error" +  error);
      this.showError("Error:Connecting to Device");
    });
  }

  deviceConnected() {
    // Subscribe to data receiving as soon as the delimiter is read
    this.bluetoothSerial.subscribe('\n').subscribe(success => {
      this.handleData(success);
      this.showToast("Connected Successfullly");
    }, error => {
      this.showError(error);
    });
  }

  deviceDisconnected() {
    // Unsubscribe from data receiving
    this.bluetoothSerial.disconnect();
    this.showToast("Device Disconnected");
  }

  handleData(data) {
    this.showToast(data);
  }

  sendData() {
    this.dataSend += '\n';
    this.showToast(this.dataSend);
    this.bluetoothSerial.write(this.dataSend).then(success => {
      this.showToast(success);
    }, error => {
      this.showError(error)
    });
  }

  async showError(error) {
    const alert = await this.alertCtrl.create({
      message: 'Error',
      subHeader: error,
      buttons: ['Dismiss']
    });
    await alert.present();
  }

  async showToast(msj: string) {
    const toast = await this.toastCtrl.create({
      message: msj,
      duration: 1000
    });
    toast.present();
  }
}
interface pairedlist {
  "class": number,
  "id": string,
  "address": string,
  "name": string
}```

[rajneshbiz]

I am getting the same information can someone please guide ?

thanks for little help.

[joran-github]

In order to connect a client, you have to start a server socket on the other device.

The code that manage the sever part is disabled in this library. So, you can only build a client.

I succeed to make it working from Android to Android by uncomenting a part code and by changing UUID.

To sum up: this library is not complete, it has been build for a specific use case (connection with Arduino) and seems to not be maintained anymore. It's a shame that ionic proposes it as a bluetooth serial solution in their documentation!

[ashefor]

I had similar issue and battled for hours but it turns out all I had to do was connect and pair my phone and bluetooth printer manually from my phone bluetooth settings and then came back to the app to proceed and worked fine