Computer EngineeringComputer Engineeringand and NetworksNetworks LaboratoryLaboratory

BTnodesApplications and Architecture

Compared

Jan Beutel, Oliver Kasten, Matthias Ringwald

Juli 10, 2003

Slide 2

Initial Projects

Smart everyday objectsby attaching sensor nodes:– self aware– context sensitive– cooperative– integration into computing environment

Ad hoc networking scenarios– integrated application protocols– scalable multi-hop routing

Wearable Computing

Juli 10, 2003

Slide 3

Consumer Electronics Integration

PDA

BTnode PC Peripherals

BTnodeMobile Phone

Camera

Juli 10, 2003

Slide 4

Backend Connectivity

Bluetooth Gateway

Internet

LocalApplication

Connectivity to– application servers– other networks

Clusters of mobile networks– using GSM– using SMS services– Wireless LAN– interfacing to other sensor

networks

BTnodes

Juli 10, 2003

Slide 5

Bluetooth Piconets

S1’’ S2’’

S3’’M’’

S1 S2

S3M

S2'

S1'

M'

Communication organized in piconets– controlled by one master– up to 7 active slaves– 255 inactive (parked) slaves

Master-Slave– implements centralized control– synchronization of all slaves– only master-slave communication

Multiple piconets– separate channels– no coordination

Juli 10, 2003

Slide 6

Bluetooth Host Controller Interface– standard interface for protocol software – providing access to lower levels of the protocol stack

HCI_COMMANDHCI_EVENT

OGF OCF PARAMETERS

Bluetooth module

Host processor

Physical interfaceHost Controller Interface

RFBaseband

Audio Link Manager

L2CAP

SDP

Applications

RFCOMM ...

UART

Juli 10, 2003

Slide 7

Bluetooth Connections

Connected

Disconnected

Managed by the host controller

Statemachine for each connection

Link Layer Control & Adaptation (L2CAP)– connection-oriented– connectionless data– protocol multiplexing for a

single “air interface”– packet segmentation and reassembly– channel abstraction– encryption– security– …

Req Conn Req Disc

RFCOMM

RF

Baseband

Audio Link Manager

Applications

SDP ...

L2CAP

Host Controller Interface

Juli 10, 2003

Slide 8

Hardware RequirementsAutonomous wireless communication and computing platform

based on a Bluetooth radio module and a microcontroller.

Requirements– small form factor, low component count– standardized wireless interface– flexible and cost effective deployment of large quantities of

networking nodes

Juli 10, 2003

Slide 9

Hardware Details

61 mm

40 m

m

Generic Sensor Interfaces

UART and I2C Data Interfaces

Memory128 kB Flash244 kB SRAM4 kB EEPROM

IntegratedPIFA Antenna

LEDs,Reset,Clocks

CommunicationEricsson Bluetooth Module

CPUAtmel ATmega 128L MCU8-Bit RISC (max. 8 MHz ~8MIPS)

Power Management

Juli 10, 2003

Slide 10

Designing for Power Aware OperationFeatures

– optional switchable power supply for Bluetooth module– MCU with 6 power down modes, low idle/sleep current– frequency scaling: 7.3 MHz - 57 kHz

– single power supply (3.6 – 16 V), single internal voltage (3.3 V) – battery charge indicator– direct current access shunts for all components– internal Vcc available at every connector to power external sensor

modules

Power consumption @ 7.3 MHz [mW] max typ Lifetime [h]*– Bluetooth Connected/CPU On 250 160 12-19– Bluetooth Idle/CPU On 95 67 32-45– Bluetooth Off/CPU Idle 15 12 202-252– Bluetooth Off/CPU Sleep 6 <0.5 504-6048

*on 840 mAh Li-ion

Juli 10, 2003

Slide 11

Power Consumption Details

P

SensingTX/RX

Idle SensingTX/RX

t

Sensor Network Example: 10% duty cycle

Operation Power consumption [mW] Lifetime [h]*4 sec sensing 12 2522 sec communication 160 1954 sec idle 0.5 6048

Total duty cycle ~ 6.5 mW 421*on 840 mAh Li-ion

Juli 10, 2003

Slide 12

System Software

Lightweight OS– event-driven application model– cooperative multithreading– device drivers (UART, RTC, ADC, ...)

Programming– standard C language– high-level Bluetooth interface– system software available as library – emulation environment on Linux

Juli 10, 2003

Slide 13

Multiple Drivers and the Dispatcher

void handler( /* ... */ ) {}void main() {

btn_disp_ev_reg( RECEIVE_EV, handler, 0 );btn_disp_run();

}

handler()

read buffer

event buffer

Dispatcher

EVENT, handler funcRECEIVE_EV, handler()OTHER_EV, func2()

btn_disp_run()

RECEIVE_EV

Application handler()

read()

Driver

received_irq()Hardware

Juli 10, 2003

Slide 14

Better Avalanche Rescue through Sensors

#7#2

#4

#292

80

9 m

3 2 45 1

No Airpoc

ket

orientation, mobility

air pocket detection

heart rate, oxygen saturation

oxygen sensor

accelerometer, inclination

oximeter

Juli 10, 2003

Slide 15

Bluetooth enabled AppliancesCommunication with other Bluetooth enables devices

– standard Bluetooth profiles for SMS, object push and RFCOMM

BTnode enabled Egg Carton SMS from Egg Carton Interactive Dialog

Juli 10, 2003

Slide 16

XHOP/R-DSR Multihop NetworkBluetooth multihop source routing prototype

– integrated scalable application protocol

– based on Dynamic Source Routing (CMU)

– routing across piconet borders to support >8 nodes

Remote topology discovery– script like command

language in the payload

Performance– 1-2 sec per hop,

depending on inquiries

Juli 10, 2003

Slide 17

Other Projects using BTnodes

200 units with 16 research groups– smart objects– routing– wearable computing– perceptual computing– operating systems

VTT, FI DSG, ETH Zurich, CH

PCCV, ETH Zurich, CHTecO, University of Karlsruhe, GE

PLAY, Interactive Institute, SE TIK, ETH Zurich, CH

IFE Wearable Lab, ETH Zurich, CHNTT DoCoMo, Munich, GE

Ptolemy Group, UC Berkeley, USAArt of Technology, Zurich, CH

DistLab, Diku, Copenhagen, DKLAP, EPF Lausanne, CH

CS Department, Lancaster University, UKLSL, EPF Lausanne, CH

TinyOS Group, UC Berkeley, USAUniversity of Uppsala, SE

Bill of material 50 parts

Parts 60 USDAssembly 5 USDBluetooth 45 USD

Unit cost @ 200 units 110 USD

Juli 10, 2003

Slide 18

Hands-on experience

From tool installation to first application in less than a day

20 student projects completed

Bootcamp held

twice for related

research projects