Download - Telos Fourth Generation WSN Platform Joseph Polastre UC Berkeley Moteiv Corporation

Telos Fourth Generation WSN Platform

Joseph PolastreUC Berkeley Moteiv Corporation

2TinyOS Technology Exchange II: 2/11/2005

Design Principlesfor WSN Platforms (from HotChips 2004)

Wireless Sensor NetworksMust operate for many yearsNeed low duty cycles to achieve long lifetimes

Key to Low Duty Cycle Operation:Sleep – majority of the timeWakeup – quickly start processingActive – minimize work & return to sleep


Sleep

Majority of time, node is asleep >99%

Minimize sleep current through Isolating and shutting down individual circuits Using low power hardware

Need RAM retention Run auxiliary hardware components from low

speed oscillators (typically 32kHz) Perform ADC conversions, DMA transfers, and bus

operations while microcontroller core is stopped


Overhead of switching from Sleep to Active Mode

Wakeup

Microcontroller Radio (FSK)

10ns – 4ms typical1– 10 ms typical

2.5 ms

292 ns


Active

Microcontroller Fast processing, low active

power Avoid external oscillators

Radio High data rate, low power

tradeoffs Narrowband radios

Low power, lower data rate, simple channel encoding, faster startup

Wideband radios More robust to noise, higher

power, high data rates

External Flash (stable storage) Data logging, network code

reprogramming, aggregation High power consumption Long writes

Radio vs. Flash 250kbps radio sending 1 byte

Energy : 1.5J Duration : 32s

Atmel flash writing 1 byte Energy : 3J Duration : 78s


Telos

New design started in September 2003>12 months of work by 2+ grad students

PrinciplesEasy to useStandards basedLowest power consumption

Low standby/active current, short wakeup times


Telos Platform Low Power

Minimal port leakage Hardware isolation and buffering

Robust Hardware flash write protection Integrated antenna (50m-125m) Standard IDC connectors

Standards Based USB IEEE 802.15.4 (CC2420 radio)

High Performance 10kB RAM, 16-bit core, extensive double buffering 12-bit ADC and DAC (200ksamples/sec) DMA transfers while CPU off


TelosMeeting the Low Power Goal

All values measured at room temperature (approximately 25oC) at 3V supply voltageSource: “Telos: Enabling Low Power Wireless Sensor Network Research”

To appear, IPSN/SPOTS, April 2005


Telos Performance

200ksamples/sec sampling rate, DMA transfers, DAC Increased performance & functionality over existing designs

New “link quality indicator” predicts average packet loss

Distance (ft) Distance (ft) Distance (ft)

Pac

ket

Suc

cess

Ave

rage

LQ

I

RS

SI

Flat field range test @ 4” off ground (125m @ 1m elevation)


Prometheus:

Perpetually Powered Telos

Solar energy scavenging system for Telos

Super capacitors buffer energy

Lithium rechargeable battery as a emergency backup

Possible due to low voltage (1.8V) and low power (<15mW) consumption of Telos

Duty Cycle Light Required System Lifetime

1% 5 hrs / 1 mo 43 years

10% 5 hrs / 4 days 4 years

100% 10 hrs / 1 day 1 year

Visit the poster later today…

Source: “Perpetual Environmentally Powered Sensor Networks”

To appear, IPSN/SPOTS, April 2005


Experimentation with the Telos Platform:

Telos Sensor BoardPolastre and Dutta

Event-driven sensorboard design Configurable Sensors with Interrupt Wakeup

Microphone -- Sampling up to 200ksamples/second Variable gain, noise gating, low pass filter, configurable wakeup

Speaker – Full dynamic range 100-20000Hz >700mW output to 8 ohm speaker, 100-20000Hz

Accelerometer -- +/-5g, interrupts on light taps to heavy shaking Light sensor -- Photodiode with amplifier, configurable gain

Low Voltage operation matches Telos design principles Lithium Ion battery recharged by USB

Visit the demo later today…


TelosDesigns and Availability

Designs and Layout provided to the open source community under BSD license Available at TinyOS.net Many Telos clones now exist

Many other Telos projects in the works Telos AC adapter, Telos fire alarm system…

Tmote is the family of motes that use Telos as the reference design Commercialized by Moteiv Corporation

Download - Telos Fourth Generation WSN Platform Joseph Polastre UC Berkeley Moteiv Corporation

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