the particle computer system christian decker, albert krohn, michael beigl, tobias zimmer teco,...
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The Particle Computer System
Christian Decker, Albert Krohn, Michael Beigl, Tobias ZimmerTecO, University of KarlsruheInstitut for TelematicsTelecooperation Office (TecO)www.teco.edu
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Outline
A brief history on Particle Computer
Design requirements
Hardware
Communication protocol / Energy consumption
Particle System software
Future directions
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History of Particle Computer
Roots: EC project „Smart-Its“ (2001-2003) Goal: Augment mundane everyday objects by small
embedded electronic devices to form digital relationships
Typical Ubicomp approach
Particle 1.01 (TecO)
BTNode rev2 (ETH)
DIY Smart-It (Lancs)
Particle 2/29 (TecO)
BTNode rev3 (ETH)
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Domain
Researcher‘s office ~1200 single items
Regular office ~450 single items
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Platform Design Requirements
Support highly-mobile settings
Support ad-hoc collaboration
Environmental and activity sensing capabilities
Seamless infrastructure integration
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Particle System Architecture
Particle nodes + backend components Flat architecture / no middleware
Particle
UDP Network
ParticleDB
ParticleAnalyzer
Particle
Particle
Bridge
...
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Particle System Architecture
Particle nodes + backend components Flat architecture / no middleware
Particle
UDP Network
ParticleDB
ParticleAnalyzer
Particle
Particle
Bridge
...
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Particle System Architecture
Particle nodes + backend components Flat architecture / no middleware
Particle
UDP Network
ParticleDB
ParticleAnalyzer
Particle
Particle
Bridge
...
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Particle Communication Board
Particle Core board
PIC18F6720 microcontroller 5 MIPS@20MHz 128 KB ROM, 4 KB RAM TR1001 transceiver 512 KB flash memory 125 kbps data rate on 868MHz
(AwareCon protocol) Actuators (2 LED, 1 speaker) On-board sensors: Battery
Level, Movement Single AAA battery 15x48 mm (AAA size)
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Sensors
Sensor (a) 17x22 mm Acceleration sensor Temperature sensor Light sensor Infrared sensor Microphone
Sensor (b) Same features as sensor (a) Force sensor Additional PIC18F452 microcontroller
3rd party sensors can be integrated with the communication board overthe microproto board interface
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AwareCon Stack
Particle communication protocol, TDMA Implemented on PIC microcontroller Time frame commonly established Fully distributed, no master needed 1 slot = 13ms
~ 8ms communication phase ~ 5ms application phase
Highly scalable through CAN-like arbitration on RF
AwareCon Timeslot
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AwareCon - Arbitration
CAN arbitration on RF layer for all sending nodes Nodes select random number and interfere them on
channel (1 bit is dominant) Highest number wins
00,10,20,30,40,50,60,70,80,9
1
0 5 10 15 20 25 30 35 40 45 50 55
W-LANArbitration
AwareConArbitration
Number of Nodes
Pro
ba
bili
ty o
f n
o C
olli
sio
n RF-CAN: 50 nodes, 97% no collsions
WLAN: 50 nodes, 58% no collisions
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AwareCon – Ad hoc Capabilities
0 20 40 60 80 100 1200
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
delay [ms]
rela
tive
occ
urr
en
ce
synchronizing to network
synchronizing to single partner
12 ms book in time in synchronized network
40 ms for sync to single partner
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Energy ConsumptionV
olt
age (
V)
Date
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ConCom
Data encoded as tuples, strictly typed Type: 3 bytes, freely selectable Length: 1byte, data length Data: data to transmit
Subject = first tuple, identifies application Sentence = subject + [tuples]* Publish/subscribe model
Application subscribes on subject type Several application run parallel Tuple type reuse Cross-layer optimizations
Leng
thD
ata
...
Subject Tuple Tuple
Type
A B C 1 1
Leng
th
Dat
a
Type
S T E 2 23 5
AwareCon
ConCom
Physical
Link
Network
Transport
Application
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Cross layer optimization
Cross-layer optimization through ConCom Early shutoff for non-subscribed ConCom subjects
saves up to 91% energy
Sleep
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Particle System Architecture
ConCom is common communication language throughout the system
no middleware required
Particle
UDP Network
ParticleDB
ParticleAnalyzer
Particle
Particle
Bridge
...ConCom
ConCom
ConCom
ConCom
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Particle System Software
AwareCon Communication stack Acts like scheduler
(8ms communication, 5ms application) Hard realtime
Sensor library Access methods for all sensors Convert methods for sensor data Creates ConCom tuples
Application integrates with system libs to a single image
AwareCon
Hardware
Sensors
Application
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Particle File System
Uniform resource presentation and access model
Uniform, hierarchical namespace /dev/- direct resources, e.g. sensors,
memory, power supply, communication interface
/context/ - mediated resources, which access direct resources forcomputation, exported application functions
/usr/ - data files
Complete de-coupling of application from system libraries
AwareCon
Hardware
Sensors
Application
File System
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Access Model
Fundamental operations read(..) and write(..) – data transfer operations Resources are coupled with specific r/w methods
Example: read(1, buf, 1)
Additional operations open(..) mount(..)/umount(..) getType(..)Type System Type of resource, developer decides Compatibility in resource combinations
Resource identifier
Resource name Type Read Write
1 /dev/voltage 3 pFunc pFunc
...
VoltageSensorGet(int &v)
{
...
}
NOP()
{
;
}
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FS Application: Shell
Shell Login on a single Particle Shell functions are exported as resources in the file
system Interactively browse/call resources Combine resources through pipes
/bin/s_temp | /bin/ctupl ste | /bin/sendRF
Future work Shell scripts
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FS Application: Over-the-Air-Programming Programming is file copy!
Bridge
CompiledProgram
Particle
FTP Proxy
Network
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Performance
File system Up to 2^13 resources ~1900 bytes RAM ~2100 bytes ROM
File library ~10 kilobytes ROM
Access overhead *buf = f()
Call + store result 26 instruction cycles
read(fd,buf,1) lookup for function pointers + call + store result More parameters 100 instruction cycles
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Future Directions
Domain Move out of the office domain New target domain: business processes
Hardware Explore new communication standards (802.15.4 - zPart)
System software Build an OS around the file system
Sensor fusion Massive parallel sensor fusion in O(1) using radio channel
computing
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Further resources
http://particle.teco.edu