Example Distributed Sensor Network with TinyOS Motes

RPI ECSE – 6965/4694

Daniel Casner

2007 April 13th

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Outline

• Hardware

• Applications

• Implementation (software)

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Hardware

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Hardware

• Processing– ATmega128L– 7MHz– 64Kb RAM

• Radio– 900 MHz– 38.4 Kbps

• Storage– Program: 128Kb flash– Data: 512Kb flash

• Sensors (10 bit ADC)– Magnetometer (x,y)– Microphone– Photo– Seismic– Temperature

• Actuators– Piezoelectric buzzer

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Applications

• Temperature Estimation– Measure local temperature– Repeatedly average with neighbors– Converges to global average

• Event Notification– Detect an event– Notify whole network

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Initializing the Network

Storeneighbor

information

Power OnWait to hear

from neighborsIs new?

No

Yes

Broadcastexistence Hear from

neighbor

Periodically rebroadcast our

existence

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Source Code

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Distributed averaging algorithm

1. Take a number

2. Pick a random person

3. Average your two numbers

4. Both of you store the new number• It should be between 1 and 100

5. Go to step 2 and repeat

6. When you see the same number several times in a row, sit down.

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Even node j

On the MotesOdd node i

Send current estimate to random odd neighbor

Update local estimate

Measure local temperature

Measure local temperature

Receive message

Messagetype Returned

estimateNACK

Receive message

Average with local estimate

Send NACK

Send update

Is busy?NoYes

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Deadlock

1

4 2

3

Now what?

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With Even/Odd Roles

1

4 2

3

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Source Code

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Multi-hop event routingAt each node: Node i

Network initialization(identify all neighbors)

Initialize sensors

Send event notification to all

neighbors k ≠ j ≠ i

Node j

Detect eventReceive event

notification from neighbor

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Source Code

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References

• Source code on LMS• TinyOS – www.tinyos.net

– Download– Tutorials– Examples

• Crossbow – www.xbow.com– Mica2 Motes

• UC Berkeley – webs.cs.berkeley.edu– Original TinyOS and Mote development

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Mica2 Specifications

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Demonstrations

Off / Initializing

Neighbor discovery

Switching modes

Temp estimation

Photo event

detection

Event detected