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 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

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

4. 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

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
11/24/2018

6. 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

7. A System Architecture for Tiny Networked Devices
Jason Hill
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.
11/24/2018

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
11/24/2018

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

11. 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

12. 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

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

14. 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

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

16. 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

17. 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

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

19. 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

20. 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

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

22. 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

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

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

25. 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

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
11/24/2018

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
11/24/2018

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.
11/24/2018