Telos Fourth Generation WSN Platform Joseph Polastre UC Berkeley Moteiv Corporation
Mar 27, 2015
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
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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
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Overhead of switching from Sleep to Active Mode
Wakeup
Microcontroller Radio (FSK)
10ns – 4ms typical1– 10 ms typical
2.5 ms
292 ns
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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 : 1.5J Duration : 32s
Atmel flash writing 1 byte Energy : 3J Duration : 78s
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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
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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 voltageSource: “Telos: Enabling Low Power Wireless Sensor Network Research”
To appear, IPSN/SPOTS, April 2005
9TinyOS Technology Exchange II: 2/11/2005
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)
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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 (<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
11TinyOS Technology Exchange II: 2/11/2005
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…
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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