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Bluetooth - Apple Notification Center Service

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Description

This example demonstrates how to receive Apple Notification Center Service (ANCS) Notifications, such as phone calls, calendar events, and so on and print them out to the VCOM.

The purpose of the Apple Notification Center Service is to give Bluetooth accessories (that connect to iOS devices through a Bluetooth Low Energy link) a simple and convenient way to access notifications that are generated on iOS devices.

Terminology

  • The Apple Notification Center Service is referred to as the ANCS.

  • The publisher of the ANCS service (the iOS device) is referred to as Notification Provider (NP).

  • Any client of the ANCS service (an accessory) is referred to as a Notification Consumer (NC).

  • A notification displayed on an iOS device in the iOS Notification Center is referred to as iOS notification.

  • A notification sent by a GATT characteristic as an asynchronous message is referred to as a GATT notification.

The Apple Notifications Center Service

In its basic form, the ANCS exposes three characteristics:

  • Notification Source: UUID: 9FBF120D-6301-42D9-8C58-25E699A21DBD (notifiable)

  • Control Point: UUID: 69D1D8F3-45E1-49A8-9821-9BBDFDAAD9D9 (writable with response)

  • Data Source: UUID: 22EAC6E9-24D6-4BB5-BE44-B36ACE7C7BFB (notifiable)

All these characteristics require authorization for access.

Support for the Notification Source characteristic is mandatory, whereas support for the Control Point characteristic and Data Source characteristic is optional.

Note: In this demo project only the Notification Source characteristic is used.

A GATT notification delivered through the Notification Source characteristic contains the following information:

  • EventID: This field informs the accessory whether the given iOS notification was added, modified, or removed. The enumerated values for this field are defined in EventID Values.

  • EventFlags: A bitmask whose set bits inform an NC of specificities with the iOS notification. For example, if an iOS notification is considered “important”, the NC may display a more aggressive user interface (UI) to properly alert the user. The enumerated bits for this field are defined in EventFlags.

  • CategoryID: A numerical value providing a category in which the iOS notification can be classified. The NP will make a best effort to provide an accurate category for each iOS notification. The enumerated values for this field are defined in CategoryID Values.

  • CategoryCount: The current number of active iOS notifications in the given category. For example, if two unread emails are sitting in a user’s email inbox and a new email is pushed to the user’s iOS device, the value of CategoryCount is 3.

  • NotificationUID: A 32-bit numerical value that is the unique identifier (UID) for the iOS notification. This value can be used as a handle in commands sent to the Control Point characteristic to interact with the iOS notification.

For more information about ANCS, see the specification page.

ANCS Implementation

The software flow is as follows:

  1. First, the software initializes the peripherals, the Bluetooth stack, and logging to the virtual COM port.

  2. After the sl_bt_evt_system_boot_id event arrives, it sets up the security manager to bond with an iOS device. Then, it starts advertising.

  3. After the sl_bt_evt_gatt_mtu_exchanged_id event is received, the device is connected, and the connection parameters are negotiated. Then, the device starts searching for the ANCS service in the remote GATT with the sl_bt_gatt_discover_primary_services_by_uuid API.

  4. If it finds the ANCS service, it will start searching for the notification source characteristic in the remote GATT with the sl_bt_gatt_discover_characteristics_by_uuid API.

  5. If the notification source characteristic is found in the remote GATT, the device tries to subscribe to characteristic notification with the sl_bt_gatt_set_characteristic_notification API. If the iOS device and the EFR module are not bonded, subscribing is not possible. After the bonding is completed, enable the characteristic notification again and subscribing should work.

  6. Receiving a sl_bt_evt_gatt_characteristic_value_id event with the att_opcode == gatt_handle_value_notification means the a GATT notification is received from the remote device. In this case, the notification type is determined based on the notification UID and printed out with the ancCharValueReceivedCallback function.

The activity diagram below shows the described flow.

Flow diagram

Gecko SDK version

GSDK v4.2.1

Hardware Required

NOTE: Tested boards for working with this example:

Board ID Description
BRD2703A EFR32xG24 Explorer Kit - XG24-EK2703A
BRD2704A SparkFun Thing Plus Matter - MGM240P - BRD2704A
BRD2601B EFR32xG24 Dev Kit - xG24-DK2601B
BRD4314A BGM220 Bluetooth Module Explorer Kit - BGM220-EK4314A
BRD4108A BG22 Bluetooth SoC Explorer Kit - BG22-EK4108A

Connections Required

Connect the Bluetooth Development Kits to the PC through a compatible-cable. For example, a micro USB cable for the BGM220 Bluetooth Module Explorer Kit.

Setup

To test this application, you can either create a project based on an example project or start with a "Bluetooth - SoC Empty" project based on your hardware.

Create a project based on an example project

  1. From the Launcher Home, add your hardware to My Products, click on it, and click on the EXAMPLE PROJECTS & DEMOS tab. Find the example project with the filter "ancs".

  2. Click Create button on the Bluetooth - Apple Notification Center Service example. Example project creation dialog pops up -> click Create and Finish and Project should be generated. board

  3. Build and flash this example to the board.

Start with a "Bluetooth - SoC Empty" project

  1. Create a Bluetooth - SoC Empty project for your hardware using Simplicity Studio 5.

  2. Copy the attached src/app.c file into your project (overwriting existing app.c).

  3. Open the .slcp file. Select the SOFTWARE COMPONENTS tab and install the software components:

    • [Services] → [IO Stream] → [IO Stream: USART] → default instance name: vcom

    • [Platform] → [Board] → [Board Control] → enable Virtual COM UART

    • [Application] → [Utility] → [Log]

  4. Build and flash the project to your device.

Note:

How It Works

Follow the below steps to test the example:

  1. On your PC open a terminal program, such as the Console that is integrated into Simplicity Studio or a third-party tool terminal like TeraTerm to receive the logs from the virtual COM port.

  2. Open the EFR Connect app on your iOS device.

  3. Find your device in the Bluetooth Browser, advertising as "Empty Example", and tap Connect. Then you need accept the pairing request and allow application to display your iOS device notifications when connected for the first time.

    paring

  4. Now you should get ANCS notifications, as shown below when you get an email, a text message, an incoming call, and so on.

    ancs