1 / 38

WSN Hardware Platforms

WSN Hardware Platforms. Vinod Kulathumani Lecture uses some slides from tutorials prepared by authors of these platforms. Factors. Cost Lifetime (when almost always on, when almost always off) Performance: Speed (in ops/sec, in ops/joule) Comms range (in m, in joules/bit/m)

toan
Download Presentation

WSN Hardware Platforms

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. WSN Hardware Platforms Vinod Kulathumani Lecture uses some slides from tutorials prepared by authors of these platforms

  2. Factors • Cost • Lifetime (when almost always on, when almost always off) • Performance: • Speed (in ops/sec, in ops/joule) • Comms range (in m, in joules/bit/m) • Memory (size, latency) • Capable of concurrent operation • Reliability, security, size, packaging

  3. Types of sensor platforms • RFID equipped sensors • Smart-dust tags • typically act as data-collectors or “trip-wires” • limited processing and communications • Mote/Stargate-scale nodes • more flexible processing and communications • More powerful gateway nodes, potentially using wall power

  4. Block diagram – sensor node SENSING SUB-SYSTEM PROCESSING SUB-SYSTEM COMMUNICATION SUB-SYSTEM ACTUATION SUB-SYSTEM POWER MGMT. SUB-SYSTEM SECURITY SUB-SYSTEM

  5. Processing Subsystem: Microcontroller • von Neumann architecture (same address and data bus) • typical 4 bit, 8 bit, 16 bit or 32 bit architectures • speed 4 MHz-400MHz with 10-300 or more MIPS • operate at various power levels: • fully active: 1 to 50 mW • sleep (memory standby, interrupts active, clocks active, cpu off) • latency of wakeup is an issue • fixed point or floating point operations • multiple processors may be used (potentially on same core) • could be DSP, FPGA

  6. Processing Subsystem: Memory • SRAM: typical, 0.5KB-64MB • Typical power consumption • retained: ~100ua; read/write: ~10ma if separate chip • retained: 2ua-100ua, read/write:~5ma if in core • EEPROM:4KB-512KB, often used as program store • Flash: 256KB-1GB or beyond • Typical power consumption • retained: negligible; read/write: ~7/20ma • erase operation is expensive • Large flashes are outside of core

  7. Sensor Subsystem • Multiple types of sensors may be used: • Environmental: pressure, gas composition, humidity, light… • Motion or force: accelerometers, rotation, microphone, piezoresistive strain, position… • Electromagnetic: magnetometers, antenna, cameras… • Chemical/biochemical • Digital or analog output • MEMS enabling size, cost and power miniaturization; nano coming • Components: Transducer, Analog signal conditioning circuits, ADC, DSP

  8. Sensor Subsystem Considerations • Energy consumption in active/passive mode is relevant • Sampling rate (1Hz or lower to 5Khz or higher) • Signal resolution • ADC bits: 8, 10, 12, 16, 20 bit (affects cost) • On-chip or not • Wakeup circuits help reduce power consumption of processing • But startup time/power cycling latencies become an issue • (~1ms-1000ms or higher) • Interference, cross-talk

  9. Actuation Subsystem • Types: • Leds, buzzers, motors, sliders, pumps, gears, solenoids… • Energy consumption (idle: O(uW); active ~1-40 mW) • Startup time (~1ms-1000ms or higher)

  10. Power Management Subsystem • Voltage regulator • typical ranges: 1.8V, 3.3V, 5V • multiple voltages for various subsystem/power levels • Gauges for voltage or current • battery monitor (allows software to adapt computation) • Control of subsystems wakeup/sleep • latency is key in driving down the duty cycle • Control of platform clock rate, processor voltage

  11. Power Management Subsystem • Energy source: • volume energy density, mass energy density • peak and average current (discharge rate) • NiCd, NiMH, LiIon, LiPolymer, fuel cells • DC-DC conversion • Charger/energy harvesting/scavenging • solar, wind, vibration, heat • account for variations in supply • number of charge/discharge cycles have limits • Power supply may be external

  12. Communication Subsystem Considerations: • speed, range, power consumption, startup time • energy efficiency: joules/bit/m • signal propagation and interference characteristics • difference between receive power versus transmit power • not all devices need a receiver • choice of power level • antenna design • matching impedance

  13. Security Subsystem Some COTS radios offer security features

  14. Outline • Hardware • RFID, Spec • Mica2, XSM, Telos • Stargate • Intel imote2 • SunSpots • Sentilla

  15. Grain-sized nodes • Powered by inductive coupling to a transmission from a reader device to transmit a message back • Available commercially at very low prices • Computation power is severely limited • Can only trasmit stored unique id and variable • Hard to add any interesting sensing capability

  16. Spec Mote (2003) • size: 2x2.5mm, AVR RISC core, 3KB memory, FSK radio (CC1000), • encrypted communication hardware support, memory-mapped active messages

  17. Matchbox-sized nodes • Mica series, XSM node, Telos • 8-bit microprocessor, 4MHz CPU • ATMEGA 128, ATMEL 8535, or Motorola HCS08 • ~4Kb RAM • holds run-time state (values of the variables) of the program • ~128Kb programmable Flash memory • holds the application program • Downloaded via a programmer-board or wirelessly • Additional Flash memory storage space up to 512Kb.

  18. Mica2 and Mica2Dot 1 inch • ATmega128 CPU • Self-programming • Chipcon CC1000 • FSK • Manchester encoding • Tunable frequency • Low power consumption • 2 AA battery = 3V

  19. Basic Sensor Board • Light (Photo) • Temperature • Prototyping space for new hardware designs

  20. Mica Sensor Board • Light (Photo) • Temperature • Acceleration • 2 axis • Resolution: ±2mg • Magnetometer • Resolution: 134mG • Microphone • Tone Detector • Sounder • 4.5kHz

  21. PNI Magnetometer/Compass • Resolution: 400 mGauss • Three axis, under $15 in large quantities

  22. Ultrasonic Transceiver • Used for ranging • Up to 2.5m range • 6cm accuracy • Dedicated microprocessor • 25kHz element

  23. MicaDot Sensor Boards • “Dot” sensorboards (1”diameter) • HoneyDot: Magnetometer • Resolution: 134 mGauss • Ultrasonic Transceiver • Weather Station

  24. XSM node platform • Derived from Mica2 mote • Better sensor & actuator range • 4 Passive Infrared: ~ 25m for SUV • Sounder: ~10m • Microphone: ~ 50m for ATV • Magnetometer: ~ 7m for SUV • Better radio range ~30m • Other features: • Grenade timer • Wakeup circuits (Mic, PIR) • Adjustable frequency sounder • Integrated Mag Set/Reset

  25. Telos Platform • Low Power • Minimal port leakage • Hardware isolation and buffering • Robust • Hardware flash write protection • Integrated antenna (50m-125m) • Standard IDC connectors • Standards Based • USB • IEEE 802.15.4 (CC2420 radio) • High Performance • 10kB RAM, 16-bit core, extensive double buffering • 12-bit ADC and DAC (200ksamples/sec) • DMA transfers while CPU off • 8 MHz TI MSP 430 microcontroller

  26. TelosMeeting the Low Power Goal All values measured at room temperature (approximately 25oC) at 3V supply voltage Source: “Telos: Enabling Low Power Wireless Sensor Network Research”To appear, IPSN/SPOTS, April 2005

  27. Brick-sized node: Stargate • Mini Linux computers communicating via 802.11 radios • Computationally powerful • High bandwidth • Requires more energy (AA infeasible) • Used as a gateway between the Internet and WSN

  28. 802.11b wireless card , 23dBm (high power), ~500m range • Intel’s Stargate • 400 MHz processor • 64 MB RAM • 32 MB Flash 25¢ GPS receiver ~10m accuracy waterproof packaging w/ integrated antenna mast & base Mica-2 connects to XSMs 8 dBi collinear omnidirectional antenna 105Ah lead acid battery ! III. XSS (Stargate) Node Platform

  29. imote2 • Intel Xscale Processor PXA271 • 13 MHz to 416 MHz • Intel MMX DSP coprocessor • Computing resource like that of Stargate • 32 Mb SDRAM, 32 MB flash • 802.15.4 radio • Comes with battery board • Additional rechargeable ones attachable • Supports Linux, TinyOS and SOS operating systems • Separate .NET edition available, installed with .NET microframework

  30. imote2 - Power • Advanced signal processing possible • Yet low power consumption • Radio is low power • Processor can tuned down when not needed • Many power save modes available

  31. Beagleboard ARM Core plus DSP

  32. Java based platform: Sunspot • Sun labs project • Easy development • Can use netbeans and Eclipse to develop and debug

  33. Java based platform: Sunspot • 180MHz 32-bit ARM920T core processor • 512K RAM and 4M Flash • 2.4GHz radio with an integrated antenna • Radio is TI CC2420 (formerly ChipCon) • IEEE 802.15.4 compliant • USB interface and LEDs • Sensors • 3-axis accelerometer (with two range settings: 2G or 6G) • Temperature, light sensors • 6 analog inputs

  34. Java based platform: Sunspot Software • No operating system • Runs Java Squawk ME virtual machine on bare metal! • provides basic OS functionality • VM operates out of flash memory • device drivers in java

  35. Java based platform: Sentilla • 8 MHz processor, CC 2420 radio • Low power, low resource • 10 times smaller JVM than Squawk

  36. Reading • The platforms enabling wireless sensor networks • System architecture directions for networked sensors

  37. Assignment 1b • Review of new hardware platforms • Arduino • WaspMote • Shimmer • Dust Networks • ATMEL AVR Raven • EMBER • Particle • Focus on • Power consumption, memory, processing • Interfaces • Sensor and actuator integration • Prototype applications and demonstrations • User base

  38. References • TMote DataSheet (www.moteiv.com) • Atmel ATMEGA128L DataSheet (www.atmel.com) • ChipCon CC1000 DataSheet (www.chipcon.com) • RFM TR1000 DataSheet (www.rfm.com) • XBow Corp. (www.xbow.com) • Sentilla (www.sentilla.com) • SunSpotWorld (www.sunspotworld.com) • Andreas Savvides (http://www.eng.yale.edu/enalab/courses/eeng460a) • http://nesl.ee.ucla.edu/courses/ee202a/2003f/lectures/GP03_Vijay.ppt

More Related