1

The BTnode StoryReflections on Almost a Decade of Mote Class Devices

Jan Beutel, ETH Zurich

2

Success of the BTnode Project

The BTnodes are enabling

• Experimental Research

– XTC/S-XTC, DSN, SNIF, Lighthouse, WSN Metrics

• Engineering Education

– Lectures, tutorials and theses

• Project Collaborations

– Smart Buildings, PermaSense

• Industrial Cooperation

– Siemens, Art of Technology

• ...

2004

2002

2000

2

BTnode rev1

BTnode rev2

BTnode rev3

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The Starting Points in 2000

The BTnode Story

4

Prominent Visions of the Time…

3 2 14 33 59155

226299

215

10

200

400

600

800

1000

1200

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

ACM Publications with "Sensor Networks" in the Title

Total Annual

[MobiCom 1999]

[MobiCom 1999]

[MobiCom 2000]

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Electrical Engineering meets Computer Science

Jan Beutel

– EE background (ETH Zurich)

– Visiting researcher @ Berkeley Wireless Research Center

– PicoRadio Project Kickoff

– Starting on a PhD in Computer Engineering

Oliver Kasten

– CS background (TU Darmstadt)

– Visiting researcher @ ICSI, Berkeley

– Starting on a PhD in Pervasive Computing

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Early Influences from Berkeley

[ASPLOS 2000][Master Thesis, UC Berkeley, 2000]

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Our Own Project Drivers in 2000

•Smart everyday objects– self aware

– context sensitive

– cooperative

– integration into computing environment

• Wearable computing

•Mobile and ad hoc networking– integrated application protocols

– scalable multi-hop routing

• NCCR MICS (Terminodes) only started in 2002

display

context sensor array:

camera, light,

microphone,

GPS

distributed

reconfigurable

computer

body area

network:

wireless

communication:

WLAN, GSM,

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BTnode rev1 – Feasibility

The BTnode Story

9

BTnode rev1 – The First 4 Units

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Dual Design Strategy

• Hardware design and first cardboard prototype

• Developer kit mock-ups

– Speeding up software development

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Education: First Master Thesis based on BTnodes

• Atmel ATmega103L

– 8-Bit RISC CPU @ 3.6 MHz

– 4kB SRAM, 128kB Flash

– Only one hardware UART

– GCC toolchain

• Ericsson Bluetooth

– Point to point only

– Limited availability

– Lacking documentation

• Software

– Event driven scheduler[Master Thesis, ETH Zurich, 2000]

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Research: Bluetooth Experimentation – Inquiry Delay

1minquiring unit inquired unitN

um

ber

of

inquirie

s co

mple

ted p

er

inte

rval

Time intervals [ms]

50% (750 out of 1500) inquiriescompletedwithin interval [0, 1900] ms

= 2.2s

x50=1.9s

x95=4.7sx99=5.4s

[Kasten, PACT ‘01]

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Research: Configurable Bluetooth Ethernet Bridge

WURM hardware architecture

• CPU for:

– Legacy C-code, binary only code

– Low-intensity, background tasks

• Reconfigurable unit for:

– High-performance tasks

– Low-power tasks

• Multiple Bridges can be controlled from one host

[Walder, Personal and Ubiquitous Computing, ISWC ’02]

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Research: Bluetooth Enabled Appliances

• Communication with other Bluetooth enables devices

• Standard Bluetooth profiles for SMS, OBEX and RFCOMM

BTnode enabled Egg Carton SMS from Egg Carton Interactive Dialog

[Siegemund, Ubicomp ’02]

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BTnode rev2 – Prototype Series

The BTnode Story

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BTnode rev2 – Prototype Series with 200 Units

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61 mm

40 m

m

BTnode rev2.2 – Hardware Details

IntegratedPIFA Antenna

LEDs,Reset,Clocks

CommunicationEricsson Bluetooth Module

Generic Sensor Interfaces

UART and I2C Data Interfaces

Power Management

Memory128 kB Flash64 kB SRAM4 kB EEPROM

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

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Getting the Details Right...

• Example: design error (256k vs 64k memory chips)

– 1 month for debugging the memory interface

– 200 hand-patched BTnode rev2

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Research: TinyBT using dual Bluetooth BTnodes

• Dual frontend BTnodes

• Allowing formation of transparent Scatternets

• Bluetooth for TinyOS– good power performance due to

high throughput of Bluetooth

[Leopold, SenSys ‘03]

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Research: Prototyping Wireless Sensor Networks

• Lightweight OS

– Event-driven model

– Simple scheduler using callbacks

– Low level device drivers

– Stripped down Bluetooth stack

• Programming

– Standard C language

– System software as library

[Beutel, EWSN ‘04]

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Research: Bluetooth Multihop Network Topologies

– Initial experiments

– Time-multiplexed, dumbbell-like connections

XHOP

Large, connected

topologies

Simple, top-down

tree-building

TreeNet

Distributed tree

topology formation

Random connection

points

Streaming data

DSNtrees

[Computer Communications 2005 , SensSys ’04, IPSN ‘05]

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Research: Network Topologies Experimentation

[Beutel, IPSN 2005]

• TreeNet puzzle

– MICS Research demo at Monte Verita review 2003

– Based on BTnode rev2

– Multihop routing

– Remote execution

– First Scatternet implementation

• DSNtrees

– Based on BTnode rev3

– Largest Bluetooth network

– 70+ nodes

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Education: How fast is it to get going?

• From tool installation to first applications in less than a day

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After 3 Years of BTnodes…

• 200 units disseminated with 16 research groups

– Smart objects

– Routing algorithms

– Wearable computing

– Perceptual computing

– Software and operating systems

• Need for more devices apparent

– At the end of 2003, we only had a few specimens left to ourselves...

• Limiting factor

– Radio capabilities

VTT, FI

DSG, ETH Zurich, CH

PCCV, ETH Zurich, CH

TecO, University of Karlsruhe, GE

PLAY, Interactive Institute, SE

TIK, ETH Zurich, CH

IFE Wearable Lab, ETH Zurich, CH

NTT DoCoMo, Munich, GE

Ptolemy Group, UC Berkeley, USA

Art of Technology, Zurich, CH

DistLab, Diku, Copenhagen, DK

LAP, EPF Lausanne, CH

CS Department, Lancaster University, UK

LSL, EPF Lausanne, CH

TinyOS Group, UC Berkeley, USA

University of Uppsala, SE

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BTnode rev3 –Commercialization

The BTnode Story

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A new Era – Outsourcing and Commercialization

• Cooperation with ETH spin-off „Art of Technology“

– Advisory role as design house

– Sourcing of all components

– Outsourcing to contract manufacturer

– Quality control

– Responsible for sales and product shipments

Prototype 2nd Generation 3rd Generation

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BTnode rev3 – Commercialization with over 800 Units

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BTnode rev3 – Hardware Architecture Details

• System core– Atmel ATmega128– 256 kB SRAM– Generic IO/peripherals– Switchable power supplies– Extension connectors

• Dual radio system

• Bluetooth radio– 2.4 GHz Zeevo ZV4002

• Low-power radio– 433-915 MHz ISM

Chipcon CC1000

• On-board antennas58 mm

32

.5 m

m

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The BTnut System Software

• Multi-threaded OS frame in C– Standard open-source tools

• Built on top of Nut/OS framework– Oriented towards networking applications

– Non-preemptive, cooperative multi-threading

• Rapid prototyping– HW emulation on Linux PC

• Debugging support– Built in OS tracer (μsec resolution)

– Storage of OS events

[btnode]$trace oneshot TRACE mode ONESHOT, restarted

[btnode]$trace TRACE STATUS

Mode is ONESHOT

Size is 500

contains 77 elements

[btnode]$trace print 10

TRACE contains 500 items, printing 10 items.

TAG PC/Info Time[s:ms:us]

---------------------------------------------------

Thread Yield idle 13:524:336

Thread Sleep LED 13:524:604

Thread Yield idle 13:581:857

simulate

emulateupload

compile

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The BTnode Platform – Beyond Hard- and Software…

• Hardware and system software don’t yet make a platform…

• Documentation resources

• Demo applications and tutorial

• Developer kit & Installer CDROM

• The BTnode community

– Development hosted on sourceforge.net

– Webpage & Mailing list

The BTnode Platform is a system solution for fast-prototyping of sensor network applications.

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Education: Lectures and Labs

• Graduate labs using the BTnode Tutorial

– Embedded Systems (EE, 150 students)

– Wireless Sensor Networks (CS, 30 students)

• Biannual undergraduate robotics lab using Lego Mindstorms

• 60+ successfully completed student projects

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Education: Hands-on Conference Tutorials

• Build your own WSN application in under 3 hours

– Originating in lectures at ETH Zurich

– Minimum prerequisites required

– Introduction to BTnodes

– Installation of tools

– My first multi-hop BTnut app

– Interfacing to handhelds/SMS

• Held at EWSN 2007 and INSS 2007

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Research: In-situ Power Profiling Function

0 100 200 300 400 500 600 700 800 900 100010

15

20

25

30

35

40

45

50

Slave sniff

Master sniff

Slave active

Master active

mA

samplesStandby

[Negri, EWSN ’06, CCNC ‘06]

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• Bluetooth Mesh Networking based on BTnode Spec

Research: Topology Control Algorithms

Paper-grade algorithm to robust implementation

[Wattenhofer ‘04]

Experiments, measurements and evaluation

[Dyer, AHSP ‘07]

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Research: Deployment of Sensor Networks

• Tools and methodology for deployment and validation

[Ringwald, DCOSS ‘07]

[Wöhrle, EmNets ‘07]

Passive Inspection

[Beutel, IPSN ‘05, EWSN ‘07]

Testbeds

Automated Testing

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Project: PermaSense Testbed

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Industry: Siemens Building Technologies

• Safety Critical Sensor Networks for Buildings

• CTI Project with Siemens Building Technologies (Zug)

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Looking Back – Outreach

The BTnode Story

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Research Impact

• Spurred interdisciplinary research

• 100+ scientific publications based on or related to BTnodes

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Worldwide Technology Transfer

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Kore

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DK

Pakis

tan

CH D S

CH D D

BTnode rev3 sales 2004-2007BTnodes

USB Adapter

Developer Kits

• BTnode rev3 devices sold to customers from 17 countries

• Commercial replicas resulting from open source policy

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A True NCCR MICS Success Story

• BTnodes have been present at every MICS event

– Presentations, Posters, Demos, Hands-on Tutorials, Reviews, Industry Forum, Conferences, Newsletter, Press, …

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Recognition in the ETH Annual Report 2006

• BTnodes are one of four highlight features

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http://www.btnode.ethz.ch

BTnode Online Resources