Bluetooth LE with CoreBluetooth

My talk introducing Bluetooth Low Energy and Apple's CoreBluetooth API for iOS and OS X.

Presented at Melbourne Cocoaheads, Feb 2013.

Transcript

1. Bluetooth LE
   with CoreBluetooth
   Chris Miles
   http:/
   /chrismiles.info/
   @chrismiles
   Melbourne CocoaHeads – Feb 2013
   

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2. CoffeeAddict
   (demo)
   

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3. Bluetooth Low Energy
   A feature of Bluetooth 4.0
   Low power, low latency wireless applications
   Healthcare, fitness, security, home
   entertainment, home automation, proximity,
   toys, ...
   

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4. Bluetooth Low Energy
   

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5. Bluetooth Low Energy
   No system-level pairing
   Device “driver” embedded in app
   No need for MFI Licensing
   “Indies” can build both the hardware and
   software
   

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6. Bluetooth LE
   iPhone 4S onwards
   iPad 3rd gen onwards
   iPad Mini
   iPod Touch 5th Gen
   Recent MacBook Pros and Airs and Mac Mini
   iOS Simulator
   

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7. CoreBluetooth
   #import
   - (void)scanForDevices
   {
   CBCentralManager *centralManager = [[CBCentralManager alloc] initWithDelegate:self
   queue:nil];
   [centralManager scanForPeripheralsWithServices:@[@"180D"] // heart rate service
   options:nil];
   self.centralManager = centralManager;
   }
   

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8. CoreBluetooth
   #pragma mark - CBCentralManagerDelegate
   - (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral
   *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI
   {
   NSString *localName = [advertisementData objectForKey:CBAdvertisementDataLocalNameKey];
   if (localName && [localName rangeOfString:@"HRM"].location != NSNotFound) {
   ! // Found heart rate monitor
   !
   ! [self stopScanningForDevices];
   !
   ! self.wahooHRMPeripheral = peripheral; // must retain it
   ! peripheral.delegate = self;
   !
   ! [central connectPeripheral:peripheral options:nil];
   }
   }
   - (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral
   *)peripheral
   {
   NSArray *services = @[ [CBUUID UUIDWithString:@"180D"] ];
   [peripheral discoverServices:services];
   }
   

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9. CoreBluetooth
   #pragma mark - CBPeripheralDelegate
   - (void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error
   {
   for (CBService *service in peripheral.services) {
   ! [peripheral discoverCharacteristics:nil
   forService:service];
   ! }
   }
   }
   

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10. CoreBluetooth
    - (void)peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService
    *)service error:(NSError *)error
    {
    if ([service.UUID isEqual:[CBUUID UUIDWithString:@"180D"]]) {
    for (CBCharacteristic *characteristic in service.characteristics) {
    if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:@"2A39"]]) {
    // Enable heart rate sensor
    UInt8 value = 0x01;
    NSData *data = [NSData dataWithBytes:&value
    length:sizeof(value)];
    [peripheral writeValue:data
    forCharacteristic:characteristic
    type:CBCharacteristicWriteWithResponse];
    }
    else if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:@"2A37"]]) {
    // Request heart rate notifications
    [peripheral setNotifyValue:YES
    forCharacteristic:characteristic];
    }
    }
    }
    }
    

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11. CoreBluetooth
    - (void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:
    (CBCharacteristic *)characteristic error:(NSError *)error
    {
    if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:@"2A37"]]) {
    // BPM
    ! NSData *data = [characteristic value];
    !
    ! const uint8_t *reportData = [data bytes];
    ! uint16_t bpm = 0;
    !
    ! if ((reportData[0] & 0x01) == 0) {
    ! /* uint8 bpm */
    ! bpm = reportData[1];
    ! }
    ! else {
    ! /* uint16 bpm */
    ! bpm = CFSwapInt16LittleToHost(*(uint16_t *)(&reportData[1]));
    ! }
    !
    ! [self didReceiveHeartrate:bpm];
    }
    }
    

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12. CBCentralManager
    CBPeripheral
    CBService
    CBCharacteristic
    NSData
    Central Scanning
    Peripheral Advertising
    Peripheral
    Service
    Characteristic
    Value
    Heartrate
    BPM
    Location
    85 “Chest”
    

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13. CoreBluetooth
    iOS Device can be a peripheral
    CBPeripheralManager, CBCentral
    CBMutableService, CBMutableCharacteristic
    New in iOS 6
    

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14. CoreBluetooth
    Event-based peripherals
    App can be suspended, is woken up on
    event
    Session-based peripherals
    Full access to peripheral in background
    Requires info.plist entry
    iOS Background Modes
    

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15. CoreBluetooth
    Session 703 “Core Bluetooth 101”
    Session 705 “Advanced Core Bluetooth”
    https:/
    /developer.apple.com/hardwaredrivers/
    BluetoothDesignGuidelines.pdf
    WWDC 2012
    

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16. TI SensorTag
    Accelerometer
    Gyroscope
    Magnetometer
    IR Temperature + ambient
    Barometric pressure
    Humidity
    

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17. TI SensorTag
    

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18. TI SensorTag
    Texas Instruments
    US$25 !!
    http:/
    /www.ti.com/sensortag
    SensorTag iOS app in App Store
    

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19. Chris Miles
    Freelance iOS Specialist
    Software Engineer
    http:/
    /chrismiles.info/
    @chrismiles
    

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