Nov 13, 2018 I’m trying to scan bluetooth devices for a room presence sensor, but the MAC addresses i’m getting make no sense, though admittedly i’m a noob regarding bluetooth and BLE. I have an android watch which i’m trying to monitor, and it appears twice in the output on every scan - once with a MAC address which i dont recognize (and seems to change on every reset), under the BLE distance. 14) And one more thing - Car Scanner provides the widest variety of features for FREE across the Play Market. The app requires a Wi-Fi or Bluetooth or Bluetooth 4.0 (Bluetooth LE) OBD2 ELM327 compatible adapter (device) to work. ELM327 devices plugs into the diagnostics socket in the car and gives your phone access to car diagnostics. This guide is Part One of a planned three-part series. In this first part, we focus on ejecting Expo and setting up React Native to interface with the Bluetooth capabilities of the phone. In the second part, we’ll explore a simple Bluetooth app, and in the third, we’ll re-build the same app using Expo’s future Bluetooth API.

• Bluetooth Scanner App Mac Download
• Bluetooth Scanner App Mac Computer

What's Bluetooth?

Bluetooth is a wireless technology that makes short-range connections between devices (like your Mac, and a mouse or keyboard) at distances up to 10 meters (approximately 30 feet).

And with Bluetooth, your iPhone or iPad can create a 'Personal Hotspot' to provide Internet access for your Mac through your wireless service provider. Learn more about creating a Personal Hotspot with your iOS device.

Find out if your Mac has Bluetooth

Most Mac computers come with Bluetooth technology built-in. You can check to see if your computer supports Bluetooth:

• Look for the Bluetooth icon in the menu bar. If the Bluetooth icon is present, your computer has Bluetooth.
• Choose System Preferences from the Apple menu, then click Bluetooth. If the Bluetooth preferences lists options for enabling Bluetooth and making your device discoverable, Bluetooth is installed.
• From theApplemenu, choose About this Mac, then click More Info. Select Bluetooth from the Hardware section. If the Hardware Setting section shows information, your system has Bluetooth installed.
  

About Bluetooth menu bar icons

The Bluetooth menu bar icon in the upper-right of your display gives you information about the status of Bluetooth and connected devices:

Bluetooth is on, but there are no devices connected to your Mac. If you expect a wireless device to be connected, make sure it's turned on.

Bluetooth is on and at least one wireless device is connected.

At least one wireless device has a low battery. Click the Bluetooth icon to identify the affected device, then replace its batteries.

Bluetooth is off. Click the Bluetooth icon using a wired mouse or trackpad or the built-in trackpad on your Mac notebook and select Turn Bluetooth On.
Mac computers without built-in trackpads won’t allow Bluetooth to be turned off unless a USB mouse is connected.

Bluetooth is offline and unavailable. Restart your Mac. If the Bluetooth status doesn’t change, disconnect all USB devices and restart your Mac again. If Bluetooth continues to show as unavailable, you might need to get your Mac serviced.

Pair your Mac with a Bluetooth device

Bluetooth wireless devices are associated with your computer through a process called pairing. After you pair a device, your Mac automatically connects to it anytime it's in range.

If your Mac came with a wireless keyboard, mouse, or trackpad, they were pre-paired at the factory. Turn on the devices and your Mac should automatically connect to them when your computer starts up.

If you purchased your Apple wireless devices separately, learn how to pair them with your Mac.

After you pair a Bluetooth device with your Mac, you should see it listed in Bluetooth preferences:

Remove a Bluetooth device from your Mac

If you want to remove (unpair) a Bluetooth device from your Mac's device list, follow these steps:

1. Choose Apple menu > System Preferences, then click Bluetooth.
2. Hover the pointer over the device you want to remove, then click the button that appears next to the device's name.

After you remove a Bluetooth device, you'll have to repeat the pairing process if you want to use it again.

Connect to Bluetooth devices after wake or startup

Bluetooth devices are usually available a few moments after your Mac completes its startup process. After waking from sleep, your Mac should find Apple wireless devices right away. Other wireless devices can take up to 5 seconds to be recognized. You might need to click a button on your wireless mouse to wake it up.

Some Bluetooth devices, such as audio headsets, might disconnect to conserve the device's battery power after no audio or data is present for a certain amount of time. When this happens, you might need to push a button on the device to make it active again. Check the documentation that came with your device for more information.

Wake your computer with Bluetooth devices

You can click your paired Bluetooth mouse or press a key on your paired Bluetooth keyboard to wake your Mac. You might need to press the space bar on the keyboard.

If clicking the mouse or pressing a key doesn't wake the computer, you might need to allow wireless devices to wake up your computer:

1. Choose Apple menu > System Preferences, then click Bluetooth.
2. Click Advanced.
3. Select the checkbox next to Allow Bluetooth Devices to wake this computer.
   

Connect multiple Bluetooth devices to one computer

The official Bluetooth specifications say seven is the maximum number of Bluetooth devices that can be connected to your Mac at once.

However, three to four devices is a practical limit, depending on the types of devices used. Some devices require more Bluetooth data, so they're more demanding than other devices.t perform reliably, try turning off devices you aren't using or unpair them from your Mac.

Fix interference from other household devices

Bluetooth shares the 2.4 GHz ISM band with other household devices such as cordless telephones, wireless networks, baby monitors, and microwave ovens. If you see issues with your Bluetooth devices that you suspect might be due to frequency congestion, see AirPort and Bluetooth: Potential sources of wireless interference for further information.

Press startup keys on a Bluetooth keyboard

You can press keys immediately after startup to have your Mac perform functions like selecting a startup disk, using the recovery partition, or resetting NVRAM.

Learn more at Startup key combinations for Mac.

Communicating with Bluetooth devices over JavaScript

What if I told you websites could communicate with nearby Bluetooth devicesin a secure and privacy-preserving way? This way, heart rate monitors, singinglightbulbs, and even turtles could interact directly with a website.

Until now, the ability to interact with Bluetooth devices has been possibleonly for platform-specific apps. The Web Bluetooth API aims to change this andbrings it to web browsers as well.

Before we start #

This article assumes you have some basic knowledge of how Bluetooth LowEnergy (BLE) and the Generic Attribute Profile (GATT) work.

Even though the Web Bluetooth API specification is not finalized yet, the specauthors are actively looking for enthusiastic developers to try out this API andgive feedback on the spec and feedback on the implementation.

A subset of the Web Bluetooth API is available in Chrome OS, Chrome for Android6.0, Mac (Chrome 56) and Windows 10 (Chrome 70). This means you should be ableto request and connect to nearby Bluetooth Low Energy devices,read/write Bluetooth characteristics, receive GATT Notifications, knowwhen a Bluetooth device gets disconnected, and even read and write toBluetooth descriptors. See MDN's Browser compatibility table for moreinformation.

For Linux and earlier versions of Windows, enable the#experimental-web-platform-features flag in chrome://flags.

Bluetooth Scanner App Mac Download

Available for origin trials #

In order to get as much feedback as possible from developers using the WebBluetooth API in the field, Chrome has previously added this feature in Chrome53 as an origin trial for Chrome OS, Android, and Mac.

The trial has successfully ended in January 2017.

Security requirements #

To understand the security tradeoffs, I recommend the Web Bluetooth SecurityModel post from Jeffrey Yasskin, a software engineer on the Chrome team,working on the Web Bluetooth API specification.

HTTPS only #

Because this experimental API is a powerful new feature added to the web, it ismade available only to secure contexts. This means you'll need to build withTLS in mind.

User gesture required #

As a security feature, discovering Bluetooth devices withnavigator.bluetooth.requestDevice must be triggered by a user gesture suchas a touch or a mouse click. We're talking about listening topointerup, click, and touchend events.

Get into the code #

The Web Bluetooth API relies heavily on JavaScript Promises. If you're notfamiliar with them, check out this great Promises tutorial. One more thing,() => {} are simply ECMAScript 2015 Arrow functions.

Request Bluetooth devices #

This version of the Web Bluetooth API specification allows websites, running inthe Central role, to connect to remote GATT Servers over a BLE connection. Itsupports communication among devices that implement Bluetooth 4.0 or later.

When a website requests access to nearby devices usingnavigator.bluetooth.requestDevice, the browser prompts user with a devicechooser where they can pick one device or simply cancel the request.

The navigator.bluetooth.requestDevice function takes a mandatory object thatdefines filters. These filters are used to return only devices that match someadvertised Bluetooth GATT services and/or the device name.

For instance, to request Bluetooth devices advertising the Bluetooth GATTBattery Service:

If your Bluetooth GATT Service is not on the list of the standardized BluetoothGATT services though, you may provide either the full Bluetooth UUID or a short16- or 32-bit form.

You can also request Bluetooth devices based on the device name being advertisedwith the name filters key, or even a prefix of this name with the namePrefixfilters key. Note that in this case, you will also need to define theoptionalServices key to be able to access some services. If you don't, you'llget an error later when trying to access them.

Finally, instead of filters you can use the acceptAllDevices key to show allnearby Bluetooth devices. You will also need to define the optionalServiceskey to be able to access some services. If you don't, you'll get an error laterwhen trying to access them.

Caution:This may result in a bunch of unrelated devices being shown in the chooser andenergy being wasted as there are no filters. Use it with caution.

Connect to a Bluetooth device #

So what do you do now that you have a BluetoothDevice? Let's connect to theBluetooth remote GATT Server which holds the service and characteristicdefinitions.

Read a Bluetooth Characteristic #

Here we are connected to the GATT Server of the remote Bluetooth device. Now wewant to get a Primary GATT Service and read a characteristic that belongs tothis service. Let's try, for instance, to read the current charge level of thedevice's battery.

In the example below, battery_level is the standardized Battery LevelCharacteristic.

If you use a custom Bluetooth GATT characteristic, you may provide either thefull Bluetooth UUID or a short 16- or 32-bit form toservice.getCharacteristic.

Note that you can also add a characteristicvaluechanged event listener on acharacteristic to handle reading its value. Check out the Read CharacteristicValue Changed Sample to see how to optionally handle upcoming GATTnotifications as well.

Bluetooth Scanner App Mac Computer

Write to a Bluetooth Characteristic #

Writing to a Bluetooth GATT Characteristic is as easy as reading it. This time,let's use the Heart Rate Control Point to reset the value of the Energy Expendedfield to 0 on a heart rate monitor device.

I promise there is no magic here. It's all explained in the Heart Rate ControlPoint Characteristic page.

Receive GATT notifications #

Now, let's see how to be notified when the Heart Rate Measurementcharacteristic changes on the device:

The Notifications Sample shows you to how to stop notifications withstopNotifications() and properly remove the added characteristicvaluechangedevent listener.

Disconnect from a Bluetooth Device #

To provide a better user experience, you may want to listen for disconnection eventsand invite the user to reconnect:

You can also call device.gatt.disconnect() to disconnect your web app from theBluetooth device. This will trigger existing gattserverdisconnected eventlisteners. Note that it will NOT stop bluetooth device communication if anotherapp is already communicating with the Bluetooth device. Check out the DeviceDisconnect Sample and the Automatic Reconnect Sample to dive deeper.

Caution:Bluetooth GATT attributes, services, characteristics, etc. are invalidated whena device disconnects. This means your code should always retrieve (throughgetPrimaryService(s), getCharacteristic(s), etc.) these attributes afterreconnecting.

Read and write to Bluetooth descriptors #

Bluetooth GATT descriptors are attributes that describe a characteristic value.You can read and write them to in a similar way to Bluetooth GATTcharacteristics.

Let's see for instance how to read the user description of the measurementinterval of the device's health thermometer.

In the example below, health_thermometer is the Health Thermometer service,measurement_interval the Measurement Interval characteristic, andgatt.characteristic_user_description the Characteristic User Descriptiondescriptor.

Now that we've read the user description of the measurement interval of thedevice's health thermometer, let's see how to update it and write a customvalue.

Samples, demos and codelabs #

All Web Bluetooth samples below have been successfully tested. To enjoy thesesamples to their fullest, I recommend you install the BLE Peripheral SimulatorAndroid App which simulates a BLE peripheral with a Battery Service, a Heart RateService, or a Health Thermometer Service.

Beginner #

• Device Info - retrieve basic device information from a BLE Device.
• Battery Level - retrieve battery information from a BLE Device advertising Battery information.
• Reset Energy - reset energy expended from a BLE Device advertising Heart Rate.
• Characteristic Properties - display all properties of a specific characteristic from a BLE Device.
• Notifications - start and stop characteristic notifications from a BLE Device.
• Device Disconnect - disconnect and get notified from a disconnection of a BLE Device after connecting to it.
• Get Characteristics - get all characteristics of an advertised service from a BLE Device.
• Get Descriptors - get all characteristics' descriptors of an advertised service from a BLE Device.

Combining multiple operations #

• GAP Characteristics - get all GAP characteristics of a BLE Device.
• Device Information Characteristics - get all Device Information characteristics of a BLE Device.
• Link Loss - set the Alert Level characteristic of a BLE Device (readValue & writeValue).
• Discover Services & Characteristics - discover all accessible primary services and their characteristics from a BLE Device.
• Automatic Reconnect - reconnect to a disconnected BLE device using an exponential backoff algorithm.
• Read Characteristic Value Changed - read battery level and be notified of changes from a BLE Device.
• Read Descriptors - read all characteristic's descriptors of a service from a BLE Device.
• Write Descriptor - write to the descriptor 'Characteristic User Description' on a BLE Device.

Check out our curated Web Bluetooth Demos and official Web Bluetooth Codelabs as well.

Libraries #

• web-bluetooth-utils is a npm module that adds some convenience functions tothe API.
• A Web Bluetooth API shim is available in noble, the most popular Node.js BLEcentral module. This allows you to webpack/browserify noble without the needfor a WebSocket server or other plugins.
• angular-web-bluetooth is a module for Angular that abstracts away all theboilerplate needed to configure the Web Bluetooth API.

Tools #

• Get Started with Web Bluetooth is a simple Web App that will generate allthe JavaScript boilerplate code to start interacting with a Bluetooth device.Enter a device name, a service, a characteristic, define its properties andyou're good to go.
• If you're already a Bluetooth developer, the Web Bluetooth Developer StudioPlugin will also generate the Web Bluetooth JavaScript code for yourBluetooth device.

Tips #

A Bluetooth Internals page is available in Chrome atchrome://bluetooth-internals so that you can inspect everything about nearbyBluetooth devices: status, services, characteristics, and descriptors.

I also recommend checking out the official How to file Web Bluetooth bugspage as debugging Bluetooth can be hard sometimes.

What's next #

Check the browser and platform implementation status first to know which partsof the Web Bluetooth API are currently being implemented.

Though it's still incomplete, here's a sneak peek of what to expect in the nearfuture:

• Scanning for nearby BLE advertisementswill happen with navigator.bluetooth.requestLEScan().
• A new serviceadded event will track newly discovered Bluetooth GATT Serviceswhile serviceremoved event will track removed ones. A new servicechangedevent will fire when any characteristic and/or descriptor gets added orremoved from a Bluetooth GATT Service.

Resources #

• Stack Overflow: https://stackoverflow.com/questions/tagged/web-bluetooth
• Chrome Feature Status: https://www.chromestatus.com/feature/5264933985976320
• Chrome Implementation Bugs: https://crbug.com/?q=component:Blink>Bluetooth
• Web Bluetooth Spec: https://webbluetoothcg.github.io/web-bluetooth
• Spec Issues: https://github.com/WebBluetoothCG/web-bluetooth/issues
• BLE Peripheral Simulator App: https://github.com/WebBluetoothCG/ble-test-peripheral-android

Acknowledgements #

Thanks to Kayce Basques for reviewing this article.Hero image by SparkFun Electronics from Boulder, USA.