Overview

1. Overview A System Architecture for Tiny Networked Devices One of the original sensor device/OS group

2. New Design Themes (Mobicom02 tutorials) • Long-lived systems that can be untetheredand unattended • Low-duty cycle operation with bounded latency • Exploit redundancy and heterogeneous tiered systems • Leverage data processing inside the network • Thousands or millions of operations per second can be done using energy of sending a bit over 10 or 100 meters (Pottie00) • Exploit computation near data to reduce communication • Self configuring systems that can be deployed ad hoc • Un-modeled physical world dynamics makes systems appear ad hoc • Measure and adapt to unpredictable environment • Exploit spatial diversity and density of sensor/actuator nodes • Achieve desired global behavior with adaptive localized algorithms • Can’t afford to extract dynamic state information needed for centralized control

3. High Level (Query Based) Interfaces are Good • Programming Apps is Hard • Limited power budget • Lossy, low bandwidth communication • Require long-lived, zero admin deployments • Distributed Algorithms • Limited tools, debugging interfaces • Queries abstract away much of the complexity • Burden on the database developers • Users get: • Safe, optimizable programs • Freedom to think about apps instead of details Tutorial from Sam Madden at EWSN ‘06

4. Sensor Network TinyDB Revisited SELECT MAX(mag) FROM sensors WHERE mag > thresh SAMPLE PERIOD 64ms • High level abstraction: • Data centric programming • Interact with sensor network as a whole • Extensible framework • Under the hood: • Intelligent query processing • Fault Mitigation App Query, Trigger Data TinyDB Cougar is very similar

5. Feature Overview • Declarative SQL-like query interface • Metadata management • Multiple concurrent queries • In-network, distributed query processing • Extensible w/ new attributes, commands, aggregates • In-network, persistent storage

6. Architecture TinyDB GUI JDBC TinyDB Client API DBMS PC side 0 Mote side TinyDB query processor 2 1 8 4 5 6 Sensor network 7

7. A System Architecture for Tiny Networked Devices Jason Hill http://www.cs.berkeley.edu/~jhill http://tinyos.millennium.berkeley.edu U.C. Berkeley 9/22/2000

8. Goals: • To develop an ultra low power networked sensor platform, including hardware and software, that enables low-cost deployment of sensor networks. • To be a system level bridge that combines advances in low power RF technology with MEMS transducer technology.

9. Key Characteristics of TNDs • Small physical size and low power consumption => Limited Physical Parallelism and Controller Hierarchy => primitive direct-to-device interface • Concurrency-intensive operation • flow-thru, not wait-command-respond => must handle multiple inputs and outputs simultaneously • Diverse in Design and Usage • application specific, not general purpose • huge device variation => efficient modularity => migration across HW/SW boundary • Largely Unattended & Numerous => robust operation => narrow interfaces

10. MobiSys Tutorial, San Francisco UC Berkeley Family of Motes

11. MobiSys Tutorial, San Francisco Mica2 and Mica2Dot • ATmega128 CPU • Self-programming • Chipcon CC1000 • FSK • Manchester encoding • Tunable frequency • Lower power consumption 1 inch

12. MobiSys Tutorial, San Francisco 5” x 2.5” x 3” size <$250 total 2-axis accelerometer COTS-BOTS (UCB)Commercial Off-The-Shelf roBOTS

13. MobiSys Tutorial, San Francisco Robomote (USC) • Less than 0.000047m3 • $150 each • Platform to test algorithms for adaptive wireless networks with autonomous robots

14. MobiSys Tutorial, San Francisco Designed for large-scale research in distributed robotics and ad-hoc wireless networking. $300 each MICAbot (Notre Dame)

15. MobiSys Tutorial, San Francisco Basic Sensor Board • Light (Photo) • Temperature • Prototyping space for new hardware designs

16. MobiSys Tutorial, San Francisco 8 External Analog Inputs using Block Screw Terminals External Probes 8 channel digital I/O 1 relay driver On board 12-bit ADC 0-2.5V, 0-3V, 0-5V Ranges Stable 2.5V Reference 3V and 5V power Designed by UCLA CENS w/ Crossbow and UCB Mica Interface Board

17. MobiSys Tutorial, San Francisco Light (Photo) Temperature Acceleration 2 axis Resolution: ±2mg Magnetometer Resolution: 134mG Microphone Tone Detector Sounder 4.5kHz Mica Sensor Board

18. MobiSys Tutorial, San Francisco PNI Magnetometer/Compass • Resolution: 400 mGauss • Three axis, under $15 in large quantities

19. MobiSys Tutorial, San Francisco Used for ranging Up to 2.5m range 6cm accuracy Dedicated microprocessor 25kHz element Ultrasonic Transceiver

20. MobiSys Tutorial, San Francisco Total Solar Radiation Photosynthetically Active Radiation Resolution: 0.3A/W Relative Humidity Accuracy: ±2% Barometric Pressure Accuracy: ±1.5mbar Temperature Accuracy: ±0.01oC Acceleration 2 axis Resolution: ±2mg Designed by UCB w/ Crossbow and UCLA Mica Weather Board Revision 1.5 Revision 1.0

21. MobiSys Tutorial, San Francisco H Bridge Standard Motor Interface On-board microprocessor Motor/Servo Board

22. MobiSys Tutorial, San Francisco Interfaces a mote with: Vibration Motors Super-bright LEDs Force Sensing Accelerometer Nitinol/Flexinol contractor“muscle wire” Peltier Junction Tool for HCI research using wireless devices Connexus Interface For More Information, See:Eric Paulos. “Connexus: An Evocative Interface” Workshop on “Ad hoc Communications and Collaboration in Ubiquitous Computing Environments” New Orleans, LA. Nov 2002.

23. MobiSys Tutorial, San Francisco In Manufacturing • “Dot” sensorboards (1” diameter) • HoneyDot: Magnetometer • Resolution: 134 mGauss • Ultrasonic Transceiver • Weather Station

24. MobiSys Tutorial, San Francisco Mica Environmental Enclosure

25. Tiny OS – The Software • Provides a component based model abstracting hardware specifics from application programmer. • Capable of maintaining high levels of concurrency. • Allows multiple applications to be “running.” • Services Provided Include: • RF messaging protocols. • Periodic Timer Events. • Asynchronous access to UART data transfers. • Mechanism for Static, Persistent Storage. • Can “Swap Out” system components to get necessary functionality. • Complete applications fit in 4KB of ROM and 256B RAM.

26. Tiny OS Internals • Scheduler and Graph of Components • constrained two-level scheduling model: tasks + events • Component: • Frame (storage) • Tasks (concurrency) • Commands, and Handlers (events) • Constrained Storage Model • frame per component, shared stack, no heap • Very lean multithreading • Layering • components issue commands to lower-level components • event signal high-level events, or call lower-level commands • Guarantees no cycles in call chain

27. Event Based Programming Model • System composed of state machines • Each State Machine is a TinyOS “component” • Command and event handlers transition a component from one state to another • Quick, low overhead, non-blocking state transmissions • Allows many independent components to share a single execution context • Emerging as design paradigm for large scale systems • “Tasks” are used to perform computational work • Run to completion, Atomic with respect to each other

28. Migration of the Hardware Software Boundary • TinyOS component model propagates hardware abstractions into software. • Allows for a migrations of software components into hardware: • Example: • Bit level radio procession component could be implemented as specialized FIFO with complex pattern matching.