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