Telos Fourth Generation WSN Platform

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Telos Fourth Generation WSN Platform

• Joseph Polastre
• UC Berkeley Moteiv Corporation

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Design Principlesfor WSN Platforms (from
HotChips 2004)

• Wireless Sensor Networks
• Must operate for many years
• Need low duty cycles to achieve long lifetimes
• Key to Low Duty Cycle Operation
• Sleep majority of the time
• Wakeup quickly start processing
• Active minimize work return to sleep

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Sleep

• Majority of time, node is asleep
• gt99
• 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

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Wakeup

• Overhead of switching from Sleep to Active Mode

• Microcontroller

• Radio (FSK)

292 ns
10ns 4ms typical
2.5 ms
1 10 ms typical
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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 1.5mJ
• Duration 32ms
• Atmel flash writing 1 byte
• Energy 3mJ
• Duration 78ms

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Telos

• New design started in September 2003
• gt12 months of work by 2 grad students
• Principles
• Easy to use
• Standards based
• Lowest power consumption
• Low standby/active current, short wakeup times

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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

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TelosMeeting the Low Power Goal
All values measured at room temperature
(approximately 25oC) at 3V supply voltage Source
Telos Enabling Low Power Wireless Sensor
Network ResearchTo appear, IPSN/SPOTS, April
2005
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Telos Performance

• 200ksamples/sec sampling rate, DMA transfers, DAC
• Increased performance functionality over
  existing designs
• New link quality indicator predicts average
  packet loss

Flat field range test _at_ 4 off ground (125m _at_ 1m
elevation)
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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
  (lt15mW) consumption of Telos

Visit the poster later today
Source Perpetual Environmentally Powered Sensor
NetworksTo appear, IPSN/SPOTS, April 2005
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Experimentation with the Telos PlatformTelos
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
• gt700mW 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
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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