Presentation to look at Android's Bluetooth Stack for Sydney Android Meetup http://www.meetup.com/Android-Australia-User-Group-Sydney/events/227303382/

1. Nanik Tolaram
nanikjava@yahoo.com
naniktolaram.com
ANDROIDANDROID
BLUETOOTHBLUETOOTH
STACKSTACK

2. 
topic 2

topic 3

topic 4
Thank YouThank You
!!

3. • Android Platform Engineer@ BlocksGlobal.comAndroid Platform Engineer@ BlocksGlobal.com
• ScreenerOS –ScreenerOS – www.screener.digitalwww.screener.digital &&
LumenHealth – www.lumenhealth.coLumenHealth – www.lumenhealth.co
• Android writer for magazine.odroid.comAndroid writer for magazine.odroid.com
• AOSP Contributor - now and then :)AOSP Contributor - now and then :)
About MeAbout Me

4. The StackThe Stack

5. BluetootBluetoot
hh• Bluetooth Classic vs Bluetooth Low EnergyBluetooth Classic vs Bluetooth Low Energy
• Single Mode vs Dual ModeSingle Mode vs Dual Mode
• Different way of programmingDifferent way of programming
• Android devices are Dual Mode devicesAndroid devices are Dual Mode devices

6. Classic vsClassic vs
BLEBLE
Classic BLE
Streaming Data (headset,
speaker, etc)
Low data transfer
Up to 7 slaves Large no of slaves
Standard profiles (SPP, DUN,
PAN)
Profiles based on Generic Attribute Profile
(GATT)
Weak connection setup Strong connection setup
Wider coverage Shorter coverage
Power hungry Low power

7. Bluetooth LowBluetooth Low
EnergyEnergy• Master Slave RoleMaster Slave Role
• Low Latency Connection - 3msLow Latency Connection - 3ms

8. Generic Access ProfileGeneric Access Profile
• PRE ConnectionPRE Connection
• Determines connection, advertising and howDetermines connection, advertising and how
devices interactsdevices interacts
• Define roles –Define roles – PeripheralsPeripherals andand CentralCentral
• DefineDefine payload for Advertising Data and Scanpayload for Advertising Data and Scan
ResponseResponse
• Advertising ProcessAdvertising Process

9. Generic AttributeGeneric Attribute
ProfileProfile• POST ConnectionPOST Connection
• Define way for data transfer between devicesDefine way for data transfer between devices

Profiles → collection of
Services

Services → distinguished by
UUID

Characteristics → encapsulates
a single data point

10. Bluetooth ProfilesBluetooth Profiles
Source https://www.facebook.com/raytaccorporation/photos/a.557851494377619.1073741829.169782503184522/576294762533292/?type=3

11. BluetoothBluetooth
StackStack
App1
Android Bluetooth Framework
Bluetooth Stack
(Bluedroid / BlueZ)
Linux Kernel + FirmwareLinux Kernel + Firmware
Bluetooth Hardware
App2 App3 App4

12. Bluetooth SystemBluetooth System
FilesFiles• bluetooth.default.sobluetooth.default.so
(external/bluetooth/bluedroid)(external/bluetooth/bluedroid)
• libbluetooth_jni.so (packages/app/Bluetooth/jni)libbluetooth_jni.so (packages/app/Bluetooth/jni)
• libbt-utils.so (external/bluetooth/bluedroid)libbt-utils.so (external/bluetooth/bluedroid)
• libbt-vendor.so (hardware/<vendor>)libbt-vendor.so (hardware/<vendor>)
• libbt-hci.so (external/bluedroid/main)libbt-hci.so (external/bluedroid/main)

13. SwitchingSwitching
OnOn
libhardware.solibhardware.so
bluetooth.default.sobluetooth.default.so
Linux KernelLinux Kernel
libbluetooth_jni.solibbluetooth_jni.so
Bluetooth.apkBluetooth.apk

14. Bluez vsBluez vs
BluedroidBluedroid• Community drivenCommunity driven
• Initiate by community vs vendorInitiate by community vs vendor
• Bluez very strong in Linux worldBluez very strong in Linux world
• Bluedroid strong in Android worldBluedroid strong in Android world

15. ClassicClassic
ProgrammingProgramming• Using BluetoothSocketUsing BluetoothSocket
• Pairing process using PINPairing process using PIN
• Blocking call when connectingBlocking call when connecting
• Thread management (important !)Thread management (important !)
• Managed state connectionManaged state connection

16. BLEBLE
ProgrammingProgramming• Android 4.3+ (API 18)Android 4.3+ (API 18)
• Setting Up Bluetooth AdapterSetting Up Bluetooth Adapter
• Scanning for BLE devicesScanning for BLE devices
• Connecting to GATTConnecting to GATT
• Reading AttributesReading Attributes
• Receive NotificationReceive Notification

17. DemDem
oo

18. ThankThank
YouYou