Transcript Telos (UCB) and Tmote (Moteiv) Fourth Generation WSN Platform

Telos
Fourth Generation WSN Platform
Joseph Polastre
UC Berkeley
Moteiv Corporation
Design Principles
for 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:
– majority of the time
 Wakeup – quickly start processing
 Active – minimize work & return to sleep
 Sleep
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Sleep

Majority of time, node is asleep
 >99%

Minimize sleep current through
 Isolating and shutting down
 Using low power hardware
 Need RAM retention

individual circuits
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

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
Fast processing, low active
power
 Avoid external oscillators

External Flash (stable storage)
Data logging, network code
reprogramming, aggregation
 High power consumption
 Long writes
Radio

High data rate, low power
tradeoffs
 Narrowband radios


Low power, lower data rate,
simple channel encoding,
faster startup
Radio vs. Flash

More robust to noise, higher
power, high data rates
250kbps radio sending 1 byte
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Wideband radios


Energy : 1.5mJ
Duration : 32ms
Atmel flash writing 1 byte

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Energy : 3mJ
Duration : 78ms
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Telos

New design started in September 2003
 >12

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



Robust

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Hardware flash write protection
Integrated antenna (50m-125m)
Standard IDC connectors
Standards Based

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
Minimal port leakage
Hardware isolation and buffering
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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Telos
Meeting the Low Power Goal
All values measured at room temperature (approximately 25oC) at 3V supply voltage
Source: “Telos: Enabling Low Power Wireless Sensor Network Research”
To 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
Distance (ft)
RSSI
Average LQI
Packet Success
Flat field range test @ 4” off ground (125m @ 1m elevation)
Distance (ft)
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Distance (ft)
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Prometheus:
Perpetually Powered Telos
Duty Cycle Light Required System Lifetime



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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
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
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Experimentation with the Telos Platform:
Telos Sensor Board
Polastre and Dutta


Event-driven sensorboard design
Configurable Sensors with Interrupt Wakeup

Microphone -- Sampling up to 200ksamples/second

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Speaker – Full dynamic range 100-20000Hz

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Variable gain, noise gating, low pass filter, configurable wakeup
>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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Telos
Designs 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
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