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BTnodes - Jan Beutel and Oliver Kasten
Computer EngineeringComputer Engineeringand Networks Laboratoryand Networks Laboratory
BTnodesA Distributed Platform for
Sensor NodesHard- and Software Architecture
February 13, 2003
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BTnodes - Jan Beutel and Oliver Kasten
ProjectsSmart everyday objects
– by attaching sensor nodes:– self aware– context sensitive– cooperative– integration into computing environment
Ad hoc networking scenarios– integrated application protocols– scalable multi-hop routing
February 13, 2003
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BTnodes - Jan Beutel and Oliver Kasten
A device magnitudes smaller than a PDA …equally flexible and programmable …
… and supporting Bluetooth.
Architecture Considerations
SensingCommunication Computation
February 13, 2003
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BTnodes - Jan Beutel and Oliver Kasten
BTnode
February 13, 2003
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BTnodes - Jan Beutel and Oliver Kasten
Consumer Electronics Integration
PDA
BTnode PC Peripherals
BTnodeMobile Phone
Camera
February 13, 2003
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BTnodes - Jan Beutel and Oliver Kasten
Backend Connectivity i
Connectivity to– application servers– other networks
BTnodes
Bluetooth Gateway
Internet
LocalApplication
February 13, 2003
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BTnodes - Jan Beutel and Oliver Kasten
Backend Connectivity iiAT commands
– GSM dial in– SMS send/ receive– GSM cell information
BTnode
GSM phone
GSM
GSM Infrastructure
PSTN
Modem pool
Dial-inserver
Internet
February 13, 2003
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BTnodes - Jan Beutel and Oliver Kasten
61 mm
40 m
m
Hardware DetailsIntegrated
PIFA AntennaLEDs,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)
February 13, 2003
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BTnodes - Jan Beutel and Oliver Kasten
Power Consumption
SensingTX/RX
Idle SensingTX/RX
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
t
P
February 13, 2003
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BTnodes - Jan Beutel and Oliver Kasten
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
System Software
February 13, 2003
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BTnodes - Jan Beutel and Oliver Kasten
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
February 13, 2003
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BTnodes - Jan Beutel and Oliver Kasten
Over-the-air Software UpdatesBootloader support of the MCU
– new firmware in XHOP payload– Flash reprogramming from pre-
cached data– reprogramming of single node and
by network flooding
Per-hop performance– transmitting 10 kB: ~0.8 sec– writing to Flash: ~0.2 sec
Overall performance– ~10s to transmit, write and reboot
with 80 kB firmware
February 13, 2003
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BTnodes - Jan Beutel and Oliver Kasten
Projects using BTnodes200 units with 13 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,CHNTTDoCoMo, Munich, GE
Ptolemy Group, UC Berkeley, USAArt of Technology, Zurich, CH
DistLab, Diku, Copenhagen, DKLAP, EPF Lausanne, CH
CS Department, Lancaster University, UK
Bill of material 50 parts
Parts 90 CHFAssembly 15 CHFBluetooth 65 CHF
Unit cost @ 200 units 170 CHF
February 13, 2003
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BTnodes - Jan Beutel and Oliver Kasten
Hands-on experienceFrom tool installation to first application in less than a day
20 student projectscompleted
Hackfest
held for the second
time tomorrow
