Transcript CS294-1 Deeply Embedded Networks Platforms Sept 2, 2003 David Culler Fall 2003 University of California, Berkeley.

CS294-1 Deeply Embedded Networks
Platforms
Sept 2, 2003
David Culler
Fall 2003
University of California, Berkeley
Review of last time
• 3 different network architectures for habitat or
environmental monitoring
– Multi-levels
– Extent, duration, energy sources
• Role of mobility and adaptation
• Where was distributed control involved?
• Insight from description vs empirical evaluation?
11/6/2015
CS294-1 F03
2
Reading Materials
• G. J. Pottie and W. J. Kaiser, Wireless Integrated Network
Sensors , CACM, 43(5), May 2000.
• Mica: A Wireless Platform for Deeply Embedded Networks,
Jason Hill and David Culler, IEEE Micro., vol 22(6), Nov/Dec 2002.
• L. Doherty, B.A. Warneke, B.E. Boser, and K.S.J. Pister, "Energy
and Performance Considerations for Smart Dust." International
Journal of Parallel Distributed Systems and Networks, Volume 4,
Number 3, 2001.
• The PicoRadio Test Bed, Burghardt, Mellors, Rabaey
• PicoRadio Supports Ad Hoc Ultra-Low Power
Wireless Networking, Rabey, Ammer, da Silva, Patel,
and Roundy
11/6/2015
CS294-1 F03
3
Outline
• Touch of history
• 3 Platform Perspectives
– WINS
– estimation theory
– SmartDust – analog design, chip technology
– Mica
- systems
• WINS vision
– bi-part architecture for passive vigilance
• PicoRadio
– Incorporate programmable logic for protocol processing, as well as
signal processing
• Smart Dust
– Really serious about energy limits
– Simple, un-partitioned architecture
• Berkeley TinyOS motes take off
• Mica
– accelerate primitives not solutions
– Rich interfaces and flexible composition for cross-layer optimization
11/6/2015
CS294-1 F03
4
Early History
• 1966 Igloo White
– http://home.att.net/~c.jeppeson/igloo_white.html
• 1986 DARPA packet Radio program
Name
ADSID I (N)
ADSID I (S)
ACOUSID II
ACOUSID III
ADSID III (N)
ADSID III (S)
MODS 81 mm
11/6/2015
Model
Variant
Type
Length
-----normal
seismic
31.00 ins
MA-36
short
seismic
20.10 ins
TC-415
seismic-acoustic
53.14 ins
MA-31
seismic- acoustic
47.63 ins .
MA-33
normal seismic
37.66 ins .
MA-37
short
acoustic
20.10 ins .
mortar seismic
33.00 ins . 9.6 lbs
CS294-1 F03
Weight
26.0 lbs
13.7 lbs
38.8 lbs
37.2 lbs
37.2 lbs
13.7 lbs
5
Classic Wireless Architecture
• Partitioned system with
narrow, std interfaces
• Similar picture to 802.11 NIC
• uP are poor at driving radios
directly
– Over sampling, start symbol, …
• Partitioning driven by many
factors
– Local optimization
– Standardization
– IP protection
• Works best in wellestablished areas
• Encumbers deep innovation
– Ex: ppp for data on cell
11/6/2015
CS294-1 F03
6
Emergences of WINS
• 1994 Pottie and Kaiser propose Low Power Wireless Integrated
Microsensor
– LWIM nodes built around 1996
• DARPA Sensit Program
• Late 97-98 handhelds emerge
–
–
–
–
palm
ITSY, BWRC PicoRadio, Srivastava UCLA, Chandrakasan MIT, …
Matchbox PCs
Bluetooth promised
• Berkeley SmartDust
– 1999 WeC mote offshoot
•
•
•
•
•
SCADDS (USC/UCLA) pc104s & tags
00 Mote / TinyOS platforms
WINS ng finally appears in Linux for Sensit
02 Mica NEST OEP creates de facto platform
03 Bluetooth revival
11/6/2015
CS294-1 F03
7
WINS case for distributed sensor nets
• must distribute to detect reliably regardless of $
– All signals decay with distance (r^2) + absorption, scattering,
dispersion, …even with line of sight
– Often need to track multiple objects
– Obstructions, clustering
• Detection and estimation theory
– observables {Xj} – sample outputs of sensors
» target signal plus background noise & interference
– features {fk} – reduced representation of observations
» Fourier, LPC, wavelet coefficients
– hypotheses {hi} – presence/absence based on estimates of feature set
– Choose hi if P(hi | {fk} ) > P(hj | {fk} ) for j != I
– Reliability: number of independent observations and SNR
– Complexity: dimensions of feature space, # hypotheses
=> More observations, rather than more processing per observation
=> Short range means better SNR
=> Fewer targets (hypoth’s) in range of set of sensors
=> Nearly homogeneous over small regions
11/6/2015
CS294-1 F03
8
Radio propagation
• Energy required to transmit distance d
– Et = bdn
– n is about 2 in freespace, about 4 near ground
– Indoor has lots of other complications
• Small energy => short range
+ Allows spatial multiplexing
– Multihop routing required to achieve distance
» Energy per hop is more
+ routes around obstacles
– Requires discovery, topology formation, maintenance
» may dominate cost of communication
– Requires media access control
» Time, space, frequency, …
• Energy to receive ~ Et at short range
– Dominated by listening time (potential receive)
– Radio must be OFF most of the time!
• WINS asserts diversity through spreading & coding
11/6/2015
CS294-1 F03
9
Passive Vigilance
Parts of the system must be sampling environment
all the time
– Reliable detection costs too much energy
use low-cost, low resolution techniques to detect
potential event
Bring in more powerful, more costly options
(infrequently) when important
Example: seismic sensor triggering camera
Human
Processing hierarchy
Sophisticated
Methods
=> Introduces processing, storage, and
Collaboration of
WINS nodes
communication issues
Higher-energy
processing &
sensing
11/6/2015
CS294-1 F03
Energy
thresholding
10
WINS node arch
• Two-part architecture
• Combine network performance info, synch, BW reservations,
into data messages
• Morphed into Sensoria automotive telematics
– www.sensoria.com
• Observe variant on classical partitioning
11/6/2015
CS294-1 F03
11
PicoRadio Concept Arch
• Embedded proc. for appln and protocol stack
– High complexity, low frequency
• Reconfigurable logic between uP and simple radio front
end
• Powerful data processing (SW radio) on the side
• Potentially rich interfaces through FPGA
• Propose 3-stage development
– 2000: COTS, 2002:chip, 2004:better chip
11/6/2015
CS294-1 F03
12
PicoRadio I implementation (2002)
• ARM 1100 proc, 4 MB
• Bluetooth front-end (sans baseband controller)
– 130 – 300 mw @ 60 MHz, 430 – 700 @ 200Mhz
• day(s) operation on set of cell phone batteries
11/6/2015
CS294-1 F03
13
Smart Dust
• Focused even more sharply on energy
11/6/2015
CS294-1 F03
14
Energy Picture
• Li ion battery 2 J / mm2, Ultracap: 1 mJ/ mm2
• Solar 1 mW/mm2 (~1 J/day/ mm2) x 30%
– 1 uW/ mm2 indoors
• Vibration - 10 uW/g (2 mg in a mm3 of silicon)
• 1000x energy gap bottom-up analysis vs uP
– 10 – 20 pJ/inst (16 bit)
– Lots of circuit tricks (ripple carry, bus design, address reuse)
• Leakage dominated by memory
• ADC Energy increases fiercely with resolution
sensitivity
transducer
Ex: acc
11/6/2015
amp
Resolution & range
ADC
proc
1 V to 16 bits => 15 uV resolution
mV/G
CS294-1 F03
15
Communication
• Radio
– P Rmin > kTB Nf SNRmin
– Pr = Pt Gant / 16 p2(d/l)n
• 1 uJ/bit for 100m at 1 kbps ground-to-ground
– 0.1 pJ/bit in free space
• Alternatives?
– Directional
– Optical
– Powered by larger transmitters
• Optical LOS Pr = Pt Gant Arx/ 4 pd2, Gant ~ 4p/ q2
11/6/2015
CS294-1 F03
16
COTS Mote (Seth Hollar)
COTS Dust
weC Mote
• 4Mhz, 8bit MCU (ATMEL)
512 bytes RAM, 8K ROM
• 900Mhz Radio (RF Monolithics)
10-100 ft. range
•
•
•
•
Temperature Sensor
Light Sensor
LED outputs
Serial Port
All physical subsystems “exposed” to processor
=> fine-grain multithreading in SW to coordinate flows.
11/6/2015
CS294-1 F03
17
System Characteristics of WSNs
• 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 SW interfaces (but highly application specific)
11/6/2015
CS294-1 F03
18
Rene: Second Generation ‘Mote’
• A tool for experimentation
• 3 Board Sandwich.
– Main CPU board
with Radio Communication.
– Sensor Board
– Power Board
• Rich interconnection
• Allows for expansion and
customization.
• Many sensor boards:
Acceleration, Magnetic Field,
Temperature, Pressure,
Humidity, Light, and RF Signal Strength.
• Can control RF transmission strength & Sense Reception
Strength.
11/6/2015
CS294-1 F03
19
Rene @ Sensit
• UAV drops 10 nodes along road,
– hot-water pipe insulation for package
•
•
•
•
•
•
•
•
Nodes self-configure into linear network
Synchronize (to 1/32 s)
Calibrate magnetometers
Each detects passing vehicle
Share filtered sensor data with 5 neighbors
Each calculates estimated direction & velocity
Share results
As plane passes by,
29 palms, 3/01
– joins network
– upload as much of missing dataset as possible from each node when
in range
• 7.5 KB of code!
• While servicing the radio in SW every 50 us!
11/6/2015
CS294-1 F03
20
Mote Platform and Community
Services
Networking
TinyOS
WeC 99
“Smart Rock”
Rene 11/00
Small
microcontroller
- 8 kb code, 512 B
data
Simple, low-power
radio
- 10 kb
EEPROM storage
(32 KB)
11/6/2015
Simple
sensors
www.tinyos.net
Dot 9/01
Mica 1/02
Demonstrate
scale
Designed for
experimentation
NEST open exp. platform
128 KB code, 4 KB data
-sensor boards
50 KB radio
-power boards
- Intel
DARPA SENSIT,
Expeditions
Crossbow
512 KB Flash
comm accelerators
CS294-1 F03- DARPA NEST
21
Rene Power Breakdown
Active
Idle
Sleep
CPU
5 mA
2 mA
(4 cp wakeup)
5 μA
Radio
7 mA (TX)
4.5 mA (RX?)
5 μA
EE-Prom
LED’s
4 mA
0
0
Photo Diode
200 μA
0
0
Temperature
200 μA
0
0
Panasonic
CR2354 560
mAh
• But what does this mean?
– Lithium Battery runs for 35 hours at peak load and years at
minimum load!
» That’s two orders of magnitude difference!
– A one byte transmission uses the same power as approx
11000 instructions.
11/6/2015
CS294-1 F03
22
System tradeoffs: simple radio, fast
on/off, application behavior
Average Power
Consumption (mA)
Radio Receive Power Optimizations
8
Sender Overhead
Receiver Radio
Receiver CPU
7
6
5
4
3
2
1
0
None
Micro
Macro
Both
Panasonic
CR2354 560
mAh
Optimization Type
Battery Lifetime for sensor reporting every minute
Duty Cycle Estimated Battery Life
Full Time Listen
100%
3 Days
Full Time Low_Power Listen
100%
6.54 Days
Periodic Multi-Hop Listening
10%
65.4 Days
No Listen (no Multi-hop)
0.01%
Years
11/6/2015
CS294-1 F03
23
Mote Expansion Connector (v1)
• Documented hardware interface
– Swap components on either side of the connector while
preserving investment in sensors or main boards
• Sensor interfaces
–
–
–
–
–
4 lines dedicated to switching components on and off
7 analog voltage sensing lines
2 I2C busses
SPI
UART lines
• Debugging aids
– All radio-related signals: RX, TX, base band, control signals, signal
strength
• Programming interfaces
– SPI and reset signals for the main processor and the coprocessor
• Ground, Vcc for both analog and digital circuits
• 12 lines reserved for future use
11/6/2015
CS294-1 F03
24
Rene Mote Connector Schematics
11/6/2015
CS294-1 F03
25
Power Lines
• Need to control on/off state of individual sensors
– Independently switched, used as outputs
• Capability
– Sink up to 20 mA, source a bit less
– If more current is required by a sensor circuit, use MOSFETs
• No higher level protocol attached
– The place to implement functionality not provided by
standard interfaces
11/6/2015
CS294-1 F03
26
Analog Lines and AD Conversion
• Many sensors provide an analog interface
– Simple voltage dividers with photo resistors, thermistors, etc.
– Whetstone bridges, condenser microphones, etc.
• Need analog voltage sensing lines
– 10 bit ADC,  2 LSB=> 8 usable bits
–  3 mV error
– Rail-to-rail range
• Sampling rate
– Max 15.4 ksps in continuous sampling mode
– Max 4 ksps in a single sampling mode
• 8 multiplexed channels
– One dedicated to sampling BBOUT
– Sampling rate high enough for most environmental
phenomena
• Interrupt driven, or polling version
11/6/2015
CS294-1 F03
27
I2C Bus
• 2-wire serial bus: clock and data
– Clock is an “or” of all clock generators, the slowest clock generator
dictates the speed
– Bi-directional data line
• Higher level protocol than UART or SPI
– Defines a protocol for multiple device access, up to 128 devices per
bus
– Defines a multiple master arbitration
– Allows for multi-byte transactions
• Speed: up to 400 kbps
• Software and HW implementations
– Soft timing constraints mean that the use of timers is not mandatory,
use tasks instead
• Many slave devices available
– EEPROM used for logging and other permanent storage
– IO extenders, ADC converters, sensors, etc.
• other significant chip-chip interconnect is 1-wire
11/6/2015
CS294-1 F03
28
SPI
•
•
•
•
3-wire, full duplex serial bus: clock, MISO, MOSI
Connector bus defines 2 SPI busses
Speed: up to 1 mbps
Hardware support on the main processor, software
implementation on the coprocessor
• Low-voltage programming interface to ATMEL
microcontrollers
• Interaction with coprocessor
• Cyclic 16 bit distributed register
• Buffering within the SPI critical
– TI MSP provides double buffering on TX => 2X radio performance
11/6/2015
CS294-1 F03
29
UART
• A standard way for exchanging information with
a PC
– Voltage conversion and connector required, provided by the
programming board
• Available speed: 2400 bps to 115 kbps
– Most reliable for communication with PC: 19.2 kbps
– Large clock rate errors at high sending rates
• 1 byte FIFOs
– Hardware doesn’t buffer multiple bytes of either input or
output
• Operate in either polling or interrupt driven mode
– TinyOS uses UARTs in interrupt driven mode
11/6/2015
CS294-1 F03
30
What is the sensor-interface of the
future?
11/6/2015
CS294-1 F03
31
AVR Processor Core
• 8-bit “RISC” at 4, 8 or 16 MHz
• Memory
–
–
–
–
8 Kbytes of program memory (flash)
512 bytes of data RAM
512 bytes of EEPROM on chip (write: 4 ms/byte)
32 8 bit registers
• IO capabilities
– 32 general purpose IO lines
» Some lines also serve more specialized purposes, e.g. UART
» 10-bit 8-channel ADC
– Connector interface means that the IO lines serve a more specific
purposes
• Interrupts
– No external interrupts available
– No interrupt queuing
• More recent ATMEGAs
– Faster, more memory, better peripheral support
• ARM thumb and other ARMs have little peripheral support
11/6/2015
CS294-1 F03
32
Clocks and Timers a key resource
• Clock sources
– Internal high-speed resonator, low precision
– External low-speed, high-precision oscillator
» Only thing running when sleeping
– External high-speed, high-preciosn oscillator
• Counters
– 3 – 4 hardware counters
» 8 or 16 bits
» Scale & Interval
» Compare, interrupt, periodic
• Uses
– General free running clock
– Wake-up
(t0 is external 32 KHz)
– Radio timing
(mica t1 16-bit free running for bit
capture, t2 8-bit for general op)
» Critrical with RFM, not with ChipCon
– Sensor sampling
– Application scheduling
(t1 free running)
• Inherent tension between generality and precision
11/6/2015
CS294-1 F03
33
Programming the Processor
• Program the runtime memory image into a flash
– No loader, no dynamic linker
• Programming steps
– Extract the code and data segments from an executable into an SREC
file
– Erase the current contents of the flash
– Reset the processor
– Download the program
» Serial download protocol
» Each download command contains the address, and the
contents of to be stored
» 10 ms delay per byte of code
– Verify the program: read the flash, match it against the source image
– After reset, start executing C runtime
• rewrite the flash on the fly???
– Present in some uP (not Rene or Mica, yes Mica2 and dot)
• Remapping? Protection?
• Network Programming?
11/6/2015
CS294-1 F03
34
Coprocessor Circuit
• Coprocessor: ATMEL AVR AT90S2343
– 2 Kbytes of code space
– 1 MHz internal clock
• Required connections
–
–
–
–
SPI for programming the main microcontroller
RESET for the main controller
I2C for accessing EEPROM storage
Insufficient pins – I2C and SPI clock lines are shared
• Minimal capability
– Software SPI
– Software I2C
11/6/2015
CS294-1 F03
35
Radio Circuit
• RFM Monolithics TR1000 916 MHz radio
– On/off keying at 10 kbps (max. 19.2 kbps)
– Capable of 115 kbps using amplitude shift keying
– Capable of turning on in 30 us
» Low-power listening by switching on and off on a
sub-bit granularity
• Processor interface
–
–
–
–
RFM CNTRL 0 and 1 – switch between transmit, receive, and sleep
Raw, unbuffered access to transmit (RFM TX) and receive (RFM RX)
Requires DC balanced signal – an equal number of 1’s and 0’s in the signal
Sampling on reception and modulating on transmission done is software
» Too much noise in received signal to use UART for sampling
» too little flexibility offered by UART
» Imposes real time constraints on the system
• Power usage
– Transmit current: 7 mA
– Receive current: 4.5 mA
– Sleep: 5 uA
11/6/2015
CS294-1 F03
36
Radio Signal Strength
• Measuring the quality of reception from a node is
useful
– Aid in multihop routing decisions
– Help with location estimation
• Signal strength measurement
– Based on base band sampling
– Demodulated and amplified analog signal, fed into ADC channel 0
– Raw samples further processed in TinyOS
• Empirical evaluation*
19000
18000
17000
Signal strength
16000
15000
14000
13000
12000
11000
10000
9000
0
10
*Klemmer, Waterson, Whitehouse, 2000
11/6/2015
20
30
40
50
60
70
80
90
Distance from base station (feet)
CS294-1 F03
37
Radio Transmission Strength Control
• Useful in networking experiments
– Control the cell size
– Allow for power savings
• Principles of operation
– Radiated power is proportional to the square of the current on RFM
TX pin
• Signal strength control
– Controlled through a digital potentiometer (DS 1804), 0-50 kOhms
– Currently no observable effects on power usage
• Evaluation
–
–
–
–
11/6/2015
Optimal transmission at the pot setting of 10 kOhms
Changing the range from 45 to 90 feet in an indoor environment
Changing the transmit strength has no effect on power usage
Effects secondary to shape/length of the antenna
CS294-1 F03
38
LEDs
• Basic mote UI and a great debugging tool
• Power consumption: 6mA
– LED consumes as much power as the main
microcontroller
– If power is a concern, turn them off!
• LED 1 and LED 2 multiplexed with the
signal strength potentiometer control
– Use them for controlling any other DS 1804 pots, one at a time
• Many groups have built add-on segmented displays
11/6/2015
CS294-1 F03
39
New Architectures?
Embedded Network Arch.
Typical Wireless Arch. (cellphone)
audio
Codec
kbd / display
Sensor / Actuators
Application Controller
CoProc
narrow
standardized
intrerface
DSP
Multi-Purpose
Controller
protocol
accelerators
Protocol Processor
rich physical interface
RF Transceiver
RF Transceiver
• Traditional approach is to partition design into specialized
subsystems with rigid interfaces.
• TinyOS allows low and high-level processing to be interleaved.
– rich physical information can be exposed
– specialized hardware to accelerate primitives
• Enables cross-layer optimizations
11/6/2015
CS294-1 F03
40
Mica Architecture
11/6/2015
CS294-1 F03
41
Basic Packet Processing
• Key accelerators
– Start symbol detection
– Channel Synchronization
– Bit Spooling
• Potentials?
– CRC?, encrypt/decrypt
– Carrier sense? Collision detect?
11/6/2015
CS294-1 F03
42
Cross Layer Optimizations
• Low-power listening
– Shift cost from frequent receive to infrequent send so
listening is cheap
– No compromise on latency and bandwidth
– HW alternatives?
• RF wake up
– Treat radio as a sensor, rather than communication device
– Escalating event detection
• Time Synchronization
– Source/recv tightly synchronized for comm to work
» Minimize system induced variance
– Eliminate uncertainty in transmit path
• Ranging for Localization
– Signal strength, time-of-flight
11/6/2015
CS294-1 F03
43
Example Application
Environmental Monitoring
• Sample period: 4 sec
• Reporting period: 5 min
• Data analysis: in-network aggregation
Alarm Notification
• Local processing for large variation detect
• Report alarm within 4 secs
11/6/2015
CS294-1 F03
44
Optimization evaluation
• Sensing & Processing
– 15 mw
17 mJ per day
• Sleeping
– 60 uw
5038 mJ per day
• Communination
– hardware accelerators for edge capture and serialization
– 10 kbps => 50 kbps
2262 => 452 mJ/day
5x
• Rendezvous: 2x time-synchronization*
– time-stamp packets: +- 100 ms
– radio bit edge detection: +- 2 us
– radio-level timesynch
669 => 33 mj/day
20x
• Wake-up
– packet listen: 108 ms (21 ms)
54,000 => 25 mj/day
– sample radio channel for energy: 50 us
2000x
• Combined: 2AA lifetime grows from 1 year to 9 years
– dominated by sleep energy
11/6/2015
CS294-1 F03 * receiver-based alternative (Elison)
45
UC Berkeley Family of Motes
11/6/2015
CS294-1 F03
46
Mica2 and Mica2Dot
• ATmega128 CPU
1 inch
– Self-programming
• Chipcon CC1000
–
–
–
–
FSK
Manchester encoding
Tunable frequency
Byte spooling
• Power usage scales with
range
11/6/2015
CS294-1 F03
47
Basic Sensor Board
• Light (Photo)
• Temperature
• Prototyping space for
new hardware
designs
11/6/2015
CS294-1 F03
48
Mica Sensor Board
• Light (Photo)
• Temperature
• Acceleration
– 2 axis
– Resolution: ±2mg
• Magnetometer
– Resolution: 134mG
• Microphone
• Tone Detector
• Sounder
– 4.5kHz
11/6/2015
CS294-1 F03
49
COTS-BOTS (UCB)
Commercial Off-The-Shelf roBOTS
• 5” x 2.5” x 3” size
• <$250 total
• 2-axis accelerometer
11/6/2015
CS294-1 F03
50
Motor/Servo Board
• H Bridge
• Standard Motor
Interface
• On-board
microprocessor
11/6/2015
CS294-1 F03
51
Robomote (USC)
•
•
•
Less than 0.000047m3
$150 each
Platform to test algorithms for adaptive wireless networks with autonomous robots
11/6/2015
CS294-1 F03
52
MICAbot (Notre Dame)
•
•
11/6/2015
Designed for large-scale research in
distributed robotics and ad-hoc wireless
networking.
$300 each
CS294-1 F03
53
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
11/6/2015
CS294-1 F03
54
PNI Magnetometer/Compass
• Resolution: 400 mGauss
• Three axis, under $15 in large quantities
11/6/2015
CS294-1 F03
55
Ultrasonic Transceiver
•
•
•
•
Used for ranging
Up to 2.5m range
6cm accuracy
Dedicated
microprocessor
• 25kHz element
11/6/2015
CS294-1 F03
56
Mica Weather Board
• Total Solar Radiation
• Photosynthetically Active
Radiation
Revision 1.5
– 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 1.0
11/6/2015
CS294-1 F03
57
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
11/6/2015 in Ubiquitous Computing Environments”
CS294-1 F03New Orleans, LA. Nov 2002.
58
Dot Weather Boards
• “Dot” sensorboards (1” diameter)
– HoneyDot: Magnetometer
» Resolution: 134 mGauss
– Ultrasonic Transceiver
– Weather Station
11/6/2015
CS294-1 F03
59
TinyOS-driven architecture
• 3K RAM = 1.5 mm2
• CPU Core = 1mm2
– multithreaded
• RF COMM stack = .5mm2
– HW assists for SW stack
•
•
•
•
Page mapping
SmartDust RADIO = .25 mm2
SmartDust ADC 1/64 mm2
I/O PADS
• Expected sleep: 1 uW
– 400+ years on AA
• 150 uW per MHz
• Radio:
– .5mm2, -90dBm receive sensitivity
– 1 mW power at 100Kbps
• ADC:
– 20 pJ/sample
– 10 Ksamps/second = .2 uW.
11/6/2015
jhill mar 6, 2003
CS294-1 F03
60
Return of Bluetooth
http://www.tik.ee.ethz.ch/~beutel/btnode.html
iMOTE
• CPU core
Atmel
ARM
• Wireless radio
RFM /
CC
BT
Many
Digital
• Sensor interface
•
Zigbee? UWB?
ARM core
– 12MHZ
– 64kB SRAM
– 512kB FLASH
•
BT radio
– Up to +4dbm transmit
– -80dbm receive
– >30m range
•
Battery life (projected) at 1% duty cycle
– >1 month with coin cells
– >6 months with AA cells
•
I2C backbone interconnect
– 100kb/s transfer rate (up to 400kb/s in future revisions)
•
Debug connector
– UART, USB slave, JTAG
11/6/2015
CS294-1 F03
61