Core Bluetooth and BLE 101

Core BluetoothAllenlinli

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Wednesday, October

結構• ⼊入⾨門

• 簡介

• Hello World

• 中階

• 觀念解說

• Programming for Central

• 進階

• Background Processing

• Best Practices for Interacting with a Remote Peripheral Device

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⼊入⾨門簡介, Hello World

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簡介名詞與功⽤用

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BLE

• 藍⽛牙4.0分三類

• 傳統藍⽛牙技術• 藍⽛牙3.0⾼高速技術

• 最新的藍⽛牙低功耗技術（Bluetooth low energy）

• 特性：適合⼩小資料傳輸、傳輸時間少、休眠時間⻑⾧長、 低功耗

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BLE功能

• 靠⼀一顆鈕扣電池可使⽤用⼀一年• 理想傳輸距離為⼆二⼗十公尺• 也有遠距傳輸的規格可達理想傳輸距離七⼗十公尺

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BLE產品

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Core Bluetooth

• A iOS framework

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Peripheral & Central

• Central(中⼼心):

• 接收廣播，接收訊息• Peripheral(周邊):

• 發送廣播，傳送訊息

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Peripheral & Central• 例⼦子：⼼心跳偵測器(Peripheral)，發送⼼心跳頻率信號到⼿手機(Central)

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Hello World讓範例碼動起來

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Hello World

1. Mac限制2. 環境設定3. 跑Sample Code

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Ｍac限制

• 不能直接拿來使⽤用• XCode5的模擬器尚不⽀支援

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環境設定

• 安裝藍⽛牙設備到模擬器• 購買BLE dongle

• 設定mac•Testing Core Bluetooth Applications in the iOS Simulator•Step 1 - Set the NVRAM Setting•Step 2 - Attach the Bluetooth LE USB adapter•Step 3 - Verify the NVRAM Setting•Step 4 - Enable Bluetooth in the iOS Simulator

user$ sudo nvram bluetoothHostControllerSwitchBehavior="never"

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跑Sample Code

• BTLE Central Peripheral Transfer 官⽅方範例

• CoreBluetooth-Demo

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安裝BLE app

• 安裝BLE app到iPhone

• LightBlue - Bluetooth Low Energy

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Run Sample Code

• 連線：跑模擬器，開啓BLE app

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中階觀念解說 &

實作⾃自⼰己的第⼀一份程式

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觀念解說影⽚片與⽂文件

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參考⽂文件

• Core Bluetooth Programming Guide

• 以下觀念解說主要整理⾃自以上主要⽂文件

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Centrals & PeripheralsThe Two Key Players

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Centrals & Peripherals• 例⼦子：⼼心跳偵測器(Peripheral)，發送⼼心跳頻率信號到⼿手機(Central)

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Central的四個階段

• Discover

• Connect

• Explore

• Interact

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Discover(Advertising)

• Peripherals broadcast

• Central scan

• Size limit: 20 bytes

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Connect

• A central connect

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Explore

• A central discover services and characteristics of peripheral

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Structure of Peripheral

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BLE官⽅方網站

• BLE官⽅方網站 - service

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Interact

• Read

• Write

• Notify

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Programming for Central

Performing Common Central Role Tasks實作程式

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Outline

• Central manager object

• Discover

• Connect

• Explore

• Interact

• Read and write

• Subscribe

Performing Common Central Role Tasks

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Starting Up a Central

self.centralManager = [[CBCentralManager alloc] initWithDelegate:self queue:nil];

- (void)centralManagerDidUpdateState:(CBCentralManager *)central{ if (central.state != CBCentralManagerStatePoweredOn) { // In a real app, you'd deal with all the states correctly return; } // The state must be CBCentralManagerStatePoweredOn...

// ... so start scanning [self scan]; }

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Discover- (void)scan{ [self.centralManager scanForPeripheralsWithServices:@[[CBUUID UUIDWithString:TRANSFER_SERVICE_UUID]] options:@{ CBCentralManagerScanOptionAllowDuplicatesKey : @YES }]; NSLog(@"Scanning started");}

- (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI

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Connect

[self.centralManager connectPeripheral:peripheral options:nil];

- (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral{ NSLog(@"Peripheral Connected"); // Stop scanning [self.centralManager stopScan]; NSLog(@"Scanning stopped");

// Make sure we get the discovery callbacks peripheral.delegate = self;

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Explore

[peripheral discoverServices:nil];

[peripheral discoverServices:@[[CBUUID UUIDWithString:TRANSFER_SERVICE_UUID]]];

- (void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error { for (CBService *service in peripheral.services) { NSLog(@"Discovered service %@", service); ... } ...

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Explore

- (void)peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error{ // Again, we loop through the array, just in case. for (CBCharacteristic *characteristic in service.characteristics) { NSLog(@"Discovered characteristic %@", characteristic);

[peripheral discoverCharacteristics:nil];

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Read and Write Value

• Reading the Value of a Characteristic

• Writing the Value of a Characteristic

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Read Value

[peripheral readValueForCharacteristic:characteristic];

- (void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error{

NSData *data = characteristic // parse the data as needed ...

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Write Value

[peripheral writeValue:dataToWrite forCharacteristic:characteristic type:CBCharacteristicWriteWithResponse];

- (void)peripheral:(CBPeripheral *)peripheraldidWriteValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error { if (error) { NSLog(@"Error writing characteristic value: %@", [error localizedDescription]); } ...

for (CBCharacteristic *characteristic in service.characteristics) { // And check if it's the right one if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:TRANSFER_CHARACTERISTIC_UUID]]) { // If it is, subscribe to it [peripheral setNotifyValue:YES forCharacteristic:characteristic]; } }

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Notify

- (void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error{ if (error) { NSLog(@"Error discovering characteristics: %@", [error localizedDescription]); return; } NSString *stringFromData = [[NSString alloc] initWithData:characteristic.value encoding:NSUTF8StringEncoding];

for (CBCharacteristic *characteristic in service.characteristics) { if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:TRANSFER_CHARACTERISTIC_UUID]]) { [peripheral setNotifyValue:YES forCharacteristic:characteristic]; } }

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Background Processing

Core Bluetooth Background Processing for iOS Apps

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Foreground-Only Apps

• Central: Cannot scan for and discover advertising

• Peripheral: Advertising is disabled

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Take Advantage of Peripheral Connection Options

• Core Bluetooth provides a way to alert the user

• The user can decide whether bring the app back to the foreground.

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Core Bluetooth Background Execution Modes

• You must include the UIBackgroundModes key in your app’s Info.plist file.

• The system wakes up your app which is in background.

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Central Background Execution Mode

• The system wakes up your app when delegate methods are invoked.

• Multiple discoveries of an advertising peripheral are coalesced into one.

• The interval for scanning increases.

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Peripheral Background Execution Mode

• Allow your app to be woken up to handle read, write, and subscription requests.

• Allow your app to advertise:

• The local name of peripheral is not advertised.

• All service UUIDs can be discovered only by explicitly scanning for them.

• The frequency may decrease.

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Use Background Execution Modes Wisely• Try to minimize the amount of work you

do in the background.

• Must follow a few basic guidelines:

• Upon being woken up, an app has around 10 seconds complete a task.

• Should not use being woken up to perform extraneous tasks

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謝謝⼤大家

Wednesday, October