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

New Design Themes (Mobicom02 tutorials) Long-lived systems that can be untethered and 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 11/24/2018

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 11/24/2018 Tutorial from Sam Madden at EWSN ‘06

TinyDB Revisited High level abstraction: Under the hood: 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 Sensor Network Cougar is very similar 11/24/2018

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 11/24/2018

Architecture 1 2 8 4 5 6 7 TinyDB GUI TinyDB Client API DBMS PC side JDBC TinyDB Client API DBMS PC side Mote side TinyDB query processor 1 2 8 4 5 6 Sensor network 7 11/24/2018

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

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. 11/24/2018

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 11/24/2018

UC Berkeley Family of Motes MobiSys Tutorial, San Francisco UC Berkeley Family of Motes 11/24/2018

MobiSys Tutorial, San Francisco Mica2 and Mica2Dot ATmega128 CPU Self-programming Chipcon CC1000 FSK Manchester encoding Tunable frequency Lower power consumption 1 inch 11/24/2018

COTS-BOTS (UCB) Commercial Off-The-Shelf roBOTS MobiSys Tutorial, San Francisco COTS-BOTS (UCB) Commercial Off-The-Shelf roBOTS 5” x 2.5” x 3” size <$250 total 2-axis accelerometer 11/24/2018

MobiSys Tutorial, San Francisco Robomote (USC) Less than 0.000047m3 $150 each Platform to test algorithms for adaptive wireless networks with autonomous robots 11/24/2018

MobiSys Tutorial, San Francisco MICAbot (Notre Dame) Designed for large-scale research in distributed robotics and ad-hoc wireless networking. $300 each 11/24/2018

MobiSys Tutorial, San Francisco Basic Sensor Board Light (Photo) Temperature Prototyping space for new hardware designs 11/24/2018

MobiSys Tutorial, San Francisco Mica Interface Board 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 11/24/2018

MobiSys Tutorial, San Francisco Mica Sensor Board Light (Photo) Temperature Acceleration 2 axis Resolution: ±2mg Magnetometer Resolution: 134mG Microphone Tone Detector Sounder 4.5kHz 11/24/2018

PNI Magnetometer/Compass MobiSys Tutorial, San Francisco PNI Magnetometer/Compass Resolution: 400 mGauss Three axis, under $15 in large quantities 11/24/2018

Ultrasonic Transceiver MobiSys Tutorial, San Francisco Ultrasonic Transceiver Used for ranging Up to 2.5m range 6cm accuracy Dedicated microprocessor 25kHz element 11/24/2018

MobiSys Tutorial, San Francisco Mica Weather Board 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 Revision 1.5 11/24/2018 Revision 1.0

MobiSys Tutorial, San Francisco Motor/Servo Board H Bridge Standard Motor Interface On-board microprocessor 11/24/2018

MobiSys Tutorial, San Francisco Connexus Interface 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 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. 11/24/2018

MobiSys Tutorial, San Francisco In Manufacturing “Dot” sensorboards (1” diameter) HoneyDot: Magnetometer Resolution: 134 mGauss Ultrasonic Transceiver Weather Station 11/24/2018

Mica Environmental Enclosure MobiSys Tutorial, San Francisco Mica Environmental Enclosure 11/24/2018

Tiny OS – The Software RF messaging protocols. Periodic Timer Events. 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. 11/24/2018

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 11/24/2018

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 11/24/2018

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. 11/24/2018