Overview A System Architecture for Tiny Networked Devices

Overview A System Architecture for Tiny Networked Devices� One of the original sensor device/OS group 12/14/2021 CSE 4/60484: Networked Sensor Systems page 1

New Design Themes • (Mobicom 02 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 (Pottie 00) – 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 12/14/2021 2

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 12/14/2021 • Freedom to think about apps instead of details Tutorial from Sam Madden at EWSN ‘ 06 3

Tiny. DB Revisited High level abstraction: Data centric programming Interact with sensor network as a whole Extensible framework Under the hood: SELECT MAX(mag) FROM sensors WHERE mag > thresh SAMPLE PERIOD 64 ms App Query, Trigger Data Tiny. DB Intelligent query processing Fault Mitigation Cougar is very similar 12/14/2021 Sensor Network 4

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 12/14/2021 5

Architecture Tiny. DB GUI Tiny. DB Client API JDBC PC side Mote side DBMS 0 2 1 4 Sensor network 12/14/2021 Tiny. DB query processor 5 8 6 7 6

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 12/14/2021 7

Goals: n n 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. 12/14/2021 8

Key Characteristics of TNDs n Small physical size and low power consumption => Limited Physical Parallelism and Controller Hierarchy => primitive direct-to-device interface n Concurrency-intensive operation flow-thru, not wait-command-respond => must handle multiple inputs and outputs simultaneously n n Diverse in Design and Usage application specific, not general purpose n huge device variation => efficient modularity 12/14/2021 n 9

Mobi. Sys Tutorial, San Francisco 10 UC Berkeley Family of Motes 12/14/2021 10

Mobi. Sys Tutorial, San Francisco 11 Mica 2 and Mica 2 Dot • ATmega 128 CPU 1 inch – Self-programming • Chipcon CC 1000 – FSK – Manchester encoding – Tunable frequency • Lower power consumption 12/14/2021 11

Mobi. Sys Tutorial, San Francisco 12 COTS-BOTS (UCB) Commercial Off-The-Shelf ro. BOTS • 5” x 2. 5” x 3” size • <$250 total • 2 -axis accelerometer 12/14/2021 12

Mobi. Sys Tutorial, San Francisco 13 Robomote (USC) • • • Less than 0. 000047 m 3 $150 each Platform to test algorithms for adaptive wireless networks with autonomous robots 12/14/2021 13

Mobi. Sys Tutorial, San Francisco 14 MICAbot (Notre Dame) • • 12/14/2021 Designed for large-scale research in distributed robotics and ad-hoc wireless networking. $300 each 14

Mobi. Sys Tutorial, San Francisco 15 Basic Sensor Board • Light (Photo) • Temperature • Prototyping space for new hardware designs 12/14/2021 15

Mobi. Sys Tutorial, San Francisco 16 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. 5 V, 0 -3 V, 0 -5 V Ranges • Stable 2. 5 V Reference • 3 V and 5 V power • Designed by UCLA CENS w/ Crossbow and UCB 12/14/2021 16

Mobi. Sys Tutorial, San Francisco 17 Mica Sensor Board • Light (Photo) • Temperature • Acceleration – 2 axis – Resolution: ± 2 mg • Magnetometer – Resolution: 134 m. G • Microphone • Tone Detector • Sounder – 4. 5 k. Hz 12/14/2021 17

Mobi. Sys Tutorial, San Francisco 18 PNI Magnetometer/Compass • Resolution: 400 m. Gauss • Three axis, under $15 in large quantities 12/14/2021 18

Mobi. Sys Tutorial, San Francisco 19 Ultrasonic Transceiver • • Used for ranging Up to 2. 5 m range 6 cm accuracy Dedicated microprocessor • 25 k. Hz element 12/14/2021 19

Mobi. Sys Tutorial, San Francisco 20 Mica Weather Board Revision 1. 5 • Total Solar Radiation • Photosynthetically Active Radiation – Resolution: 0. 3 A/W • Relative Humidity – Accuracy: ± 2% • Barometric Pressure – Accuracy: ± 1. 5 mbar • Temperature – Accuracy: ± 0. 01 o. C • Acceleration – 2 axis – Resolution: ± 2 mg • Designed by UCB w/ Crossbow and UCLA 12/14/2021 Revision 1. 0 20

Mobi. Sys Tutorial, San Francisco 21 Motor/Servo Board • H Bridge • Standard Motor Interface • On-board microprocessor 12/14/2021 21

Mobi. Sys Tutorial, San Francisco 22 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 12/14/2021 22 Collaboration in Ubiquitous Computing Environments” New Orleans, LA. Nov 2002.

Mobi. Sys Tutorial, San Francisco 23 In Manufacturing • “Dot” sensorboards (1” diameter) – Honey. Dot: Magnetometer » Resolution: 134 m. Gauss – Ultrasonic Transceiver – Weather Station 12/14/2021 23

Mobi. Sys Tutorial, San Francisco 24 Mica Environmental Enclosure 12/14/2021 24

Tiny OS – The Software n n 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. n Periodic Timer Events. n Asynchronous access to UART data transfers. n Mechanism for Static, Persistent Storage. n Can “Swap Out” system components to get necessary functionality. 12/14/2021 n Complete applications fit in 4 KB of ROM and 256 B RAM. n 25

Tiny OS Internals n n n Scheduler and Graph of Components n constrained two-level scheduling model: tasks + events Component: n Frame (storage) n Tasks (concurrency) n Commands, and Handlers (events) Constrained Storage Model n frame per component, shared stack, no heap Very lean multithreading Layering n components issue commands to lower-level components n event signal high-level events, or call lower-level commands n Guarantees no cycles in call chain 12/14/2021 26

Event Based Programming Model n n n System composed of state machines Each State Machine is a Tiny. OS “component” Command event handlers transition a component from one state to another n n Allows many independent components to share a single execution context n n Quick, low overhead, non-blocking state transmissions Emerging as design paradigm for large scale systems “Tasks” are used to perform computational work Run to completion, Atomic with respect to 12/14/2021 each other 27 n

Migration of the Hardware Software Boundary n n n Tiny. OS component model propagates hardware abstractions into software. Allows for a migrations of software components into hardware: Example: n Bit level radio procession component could be implemented as specialized FIFO with complex pattern matching. 12/14/2021 28