1. Telos Fourth Generation WSN Platform
Joseph Polastre
UC Berkeley Moteiv Corporation
Develop control abstraction

2. 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:
Sleep – majority of the time
Wakeup – quickly start processing
Active – minimize work & return to sleep

3. Sleep Majority of time, node is asleep Minimize sleep current through
>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

4. Wakeup Overhead of switching from Sleep to Active Mode Microcontroller
Radio (FSK)
292 ns
10ns – 4ms typical
2.5 ms
1– 10 ms typical

5. Active Microcontroller Radio External Flash (stable storage)
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

6. Telos New design started in September 2003 Principles
>12 months of work by 2+ grad students
Principles
Easy to use
Standards based
Lowest power consumption
Low standby/active current, short wakeup times

7. Telos Platform Low Power Robust Standards Based High Performance
Minimal port leakage
Hardware isolation and buffering
Robust
Hardware flash write protection
Integrated antenna (50m-125m)
Standard IDC connectors
Standards Based
USB
IEEE (CC2420 radio)
High Performance
10kB RAM, 16-bit core, extensive double buffering
12-bit ADC and DAC (200ksamples/sec)
DMA transfers while CPU off

8. 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

9. 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 4” off ground 1m elevation)
Distance (ft)
Packet Success
Average LQI
RSSI

10. Prometheus: Perpetually Powered 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
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
Visit the poster later today…
Source: “Perpetual Environmentally Powered Sensor Networks” To appear, IPSN/SPOTS, April 2005

11. Visit the demo later today…
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
Variable gain, noise gating, low pass filter, configurable wakeup
Speaker – Full dynamic range Hz
>700mW output to 8 ohm speaker, Hz
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…

12. 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