Bluetooth

Technical

• Packet based Protokoll

PHY

• on the PHY BT makes a small network called Piconet …

• Frequency hopping

• TDD = Time Division Duplex topology

• TDMA = Time Division Multiple Access

physical links

• are those the connections??? .. probably not

• SCO = Synchronous connection oriented

• ACL = Asynchronous Connectionless

• Bluetooth Packet Format = Access Code(72 bits) + Header(54 bits) + Payload (0 to 2745 bits)

the protocol stack

protocols bluetooth uses

• Hostless System: wenn die Host stack und Controler stack protos am gleichen uC laufen … spaart einen uC … eg in headsets
• Control stack
  • die protos, die auf der BT Hardware implementiert sind (in hardware, oder um uC auf der BT karte)
  • ACL = Asynchronous Connectionless
  • SCO = Synchronous connection oriented
  • LMP = Link Management Protocol
  • HCI = Host Controller Interface
  • LE LL = Low Energy Link Layer
• Host stack
  • die protos, die im Betriebssystem implementiert sind
  • L2CAP = Logical Link Control and Adaptation Protokoll
  • BNEP = Bluetooth Network Encapsulation Protokoll
  • RFCOMM = Radio Frequency Communication
  • SDP = Serice Discovery Protokoll
  • TCS = Telephony Control Protokoll
  • ATT = Low Energy Attribute Protokoll
  • SMP = Low Energy Security Manager Protokoll

Bluetooth Profile

• beschreibt Dinge, die ein Device kann …
• damit ein Gerät eine bestimmte funktionalität kann … muss es bestimmte profile implementieren
• jedes Profil hat eine uuid … aber 16bit lang statt 128
• eg:
  • A2DP = Advanced Audio Distribution Profile
  • GATT = Generic Attribute Profile
    • is eg BLE = Bluetooth Low Energy … datenübertragung mit wenig Energie, bei kleinen Datenmengen
  • HFP = Hands Free Profile
    • dass schlechte Audio, welches noch SCO = Synchronous connection oriented verwendet
  • HID = Human Input Device
    • usb devices … over bluetooth
  • PAN = Personal Area Network
    • networking .. mit dem BNEP = Bluetooth Network Encapsulation Protokoll
  • SSP = Serial Port Profile
    • serielle ports… verwendet dann das RFCOMM = Radio Frequency Communication proto
  • …
• see: https://de.wikipedia.org/wiki/Bluetooth-Profile

Dual Mode

Devices, that support BLE = Bluetooth Low Energy and the classical Bluetooth

commands for info

• inxi -Eaz
• hciconfig -a

wireshark filter

not btl2cap.cid 0x03cc and not bthci_evt.code 0x13

History

• the name really comes from a skandinavian King: Harald Bluetooth in an old Vikins story

  • they wanted other names PAN and RadioWire, but then stayed on Bluetooth

• the Logo is a kombination of the Runes of those King’s initials: (https://en.wikipedia.org/wiki/Haglaz) and (https://en.wikipedia.org/wiki/Berkanan)