Presentation on smart sensor architecture development for mobile devices. Early development which eventually lead to Bluetooth 4.0.
- 1. Smart Sensor Architecture Smart Sensor System Architecture in Mimosa project Iiro Jantunen / Nokia Research Center Tutorial Ambient Intelligence, Toulouse, March 10, 20061 2006 NokiaS mart S ens or Architecture.ppt / 2006-03-10 / IJ
2. Contents What is a smart sensor system? Transducer, analog electronics, ADC , digital electronicsO pen architecture for smart sensors BluLite Public S S I protocol nanoUDP/nanoIP networking O pen API:s for developing applications for using smart sensorsMimosa architecture for smart sensors Wired & wireless BluLite or R F ID connection Many sensors in many devices over many radio technologies2 2006 NokiaS mart S ens or Architecture.ppt / 2006-03-10 / IJ 3. From sensors to smart sensors Passive sensor (photodiode)S ensorActive sensor (S T 3-axis accelerometer) Wireless smart sensor 3 2006 NokiaS mart S ens or Architecture.ppt / 2006-03-10 / IJ 4. Smart Sensor Systems C ombine functions of sensors and interfaces S ensing Amplification S ignal conditioning AD conversion Bus interfacing Include higher level functions S elf-testing Auto-calibration Data processing and evaluation C ontext awareness C ommunications Modularity and/or integration 4 2006 NokiaS mart S ens or Architecture.ppt / 2006-03-10 / IJ Transducer physical reality electrical measurable Amplifier & filtering sensor impedance, signal strength and quality Analog-digital conversion Microcontroller / DS P / AS IC Digital signal processing C ommunications to outside world Networking S erial interface (US B, S PI, MMC ) R adio interface (optional) 5. Transducer C onverts between physical propertiesMeasurementTypical/common techniques The resulting property can beAccelerationPiezoelectric, capacitiveDisplacement, position, proximityR eluctance, optoelectronic, ultrasonic, radar VoltageF lowPressure difference O ptical powerF orcePiezoresistive E lectrical measurand needs an amplifier/filtering circuit to provide electrical power, impedance etc.HumidityR esistive, capacitiveLocationG PSTimeC lock signal O ptical measurand needs a optoelectrical transducer with the same propertiesS ound, pressureC apacitiveR adiationO ptoelectronicG as concentrationTuned laser & optoelectronic E lectrical capacitance C urrent5 2006 NokiaS mart S ens or Architecture.ppt / 2006-03-10 / IJ 6. Non-ideal behavior of sensors C haracteristicS ensor DesignNonlinearityC onsistentR educeDriftMinimizeC ompensateO ffsetS ensor InterfaceC alibrateTime dependence of offsetMinimizeC alibrate/reduce Auto-zeroTime dependence of sensitivity NonrepeatabilityMC U/DS PAuto-range R educeC ross-sensitivity to temp and strainC alibrateHysteresisPredictableLow resolutionIncreaseAmplifyLow sensibilityIncreaseS tore value and correctAmplifyUnsuitable output impedanceBufferS elf-heatingIncrease coolingUnsuitable frequency responseModifyR educe power use F ilterTemperature dependence of offsetS tore value and correctTemp. dependence of sensitivityS tore value and correctF rom R . F rank: Understanding S mart S ensors, 2n ed., 6 2006 NokiaS mart S ens or Architecture.ppt / 2006-03-10 / IJ 7. Amplifying and analog filtering of sensor output Amplifier provides signal strength and sensor impedanceIssues: F iltering needed to suppress noise S ignal transmission If needed, quite complex functions can be done with analog electronics, but many functions are better done in digital electronics Data display S ignal conditioning O perating life C alibration easier Impedance of sensor and system cheaper S upply voltage need less room F requency response F iltering7 2006 NokiaS mart S ens or Architecture.ppt / 2006-03-10 / IJ 8. Analog-digital conversion (ADC) The measurement must usually be changed to digital form for further processing and calculations storing to memory sending the data or just an economical reason ADC often included in MC U:s, e.g. MS P430F 1xx Is the resolution (8 or 12-bit) enough?8 2006 NokiaS mart S ens or Architecture.ppt / 2006-03-10 / IJIssues: S ample rate R esolution (8, 12, 16-bit) Accuracy Power consumption Price 9. Digital signal processing More complex signal processing summing many sensors (e.g. 3-axis accelerometers) pattern recognition, e.g. step counters, speech recognition C an be done inIssues: F ixed-point vs. floating-point DS P Data precision S peed Power usage AS IC , for cheap mass-production Price DS P, for high-speed number crunching Internal ADC MC U (microcontroller), medium level calculations, control software9 2006 NokiaS mart S ens or Architecture.ppt / 2006-03-10 / IJ Need for flexible programming: MC U vs. DS P Programming languages: Assembly vs. C /C ++ or J ava 10. Microcontroller S oftware controlling a smart sensor system, e.g. measurements communications data memory real time clock Usually includes ADC (DAC ) timers serial ports (S PI, I2C , UAR T) flash memory Power-efficient, cheap, flexible Also called MC U or C10 2006 NokiaS mart S ens or Architecture.ppt / 2006-03-10 / IJMS P430F169 by Texas Instruments Low supply-voltage 1.8 - 3.6 V Ultra-low power consumption: Active: 330 A at 1 MHz, 2.2 V S tandby: 1.1 A O ff (R AM retention): 0.2 A Wake-up from standby in less than 6 s 16-Bit R IS C , 125-ns instruction cycle Program memory 60 kB (flash), R AM 2048 B 8-channel 12-Bit ADC with internal reference, sample-and-hold and autoscan Dual channel 12-Bit DAC with synchronization 16-Bit Timer_ A & Timer_ B with 3/7 C C R O n-chip comparator 2 serial interfaces: UAR T or S PI or I2C S upply voltage supervisor/monitor Brownout detector Bootstrap loader S erial onboard programming 11. Networking sensors over radioRF IDInternet WL ANL ow E nd Bluetooth UWB11 2006 NokiaS mart S ens or Architecture.ppt / 2006-03-10 / IJC ellular GPRS/3G network 12. BluLite (or Bluetooth Low End Extension) Low E nd E xtension for Bluetooth is designed to complement Bluetooth by creating a wireless solution that allows small devices that are limited in battery power, size, weight and cost to have a wireless connection with mobile terminals without adding yet another radio to mobile terminals (as Z igBee) O ptimized for irregular data exchange between Bluetooth enabled mobile terminals and button cell batter powered small devices C oncept assumes two device classes Dual-mode (Bluetooth 1.2 with Low E nd mode) for terminals S tand-alone (Low E nd mode alone) for sensors and enhancementsDual-mode device (i.e. terminal) E /(BB) C ommon LE MAC C ommon Host Bluetooth RF IF BB/MAC12 2006 NokiaS mart S ens or Architecture.ppt / 2006-03-10 / IJStand-alone device (e.g. 3D accelometer node) S ensor AS ICLE E AS ICStand-alone device (e.g. fitness gadget) S ensor AS ICLE E AS IC 13. BluLite radio Channels of the proposed system24012400IEEE 802.11b channel in North America and Europe24022403Bluetooth channels2480248124822483MHzLow End Extension channels24032406243324362463246624782481 MHzOne default initialization channel, non-overlapping with Bluetooth T secondary initialization channels, for jamming resistance wo 24 Unicast channels for user data 13 2006 NokiaS mart S ens or Architecture.ppt / 2006-03-10 / IJ 14. BluLite radio parameters with 1 Mbps Physical bit rate 1 Mbps F requency band 2.4 G Hz (IS M band) Duplex TDD C o-existence of multiple devices C onnection setup channel C S MA Data delivery F DMAJ amming avoidance F DMA PDU payload Byte aligned, variable length, max 255 bytesBit rate excluding PHY and MAC overheads Uni-directional with AR Q , max 890 kbps Bi-directional with AR Q , max 2 x 471 kbps 14 2006 NokiaS mart S ens or Architecture.ppt / 2006-03-10 / IJ 15. Basic functions of BluLite radio ADVERTISE OFFIDLESCANCONNECTEDCONNECT 1.2. 3. 4.15ADVE RTIS E : Makes the local device visible and connectable to all remote devices within reach. Low-power protocols optimized for this state. A possibility for an application dependent trade-off between connection set-up delay and the power consumption. S C AN: R eturns the addresses and short description of the advertising remote devises within reach. C ONNE C T: E stablishes a point-to-point connection with an advertising remote device. C ONNE C TE D: Provides point-to-point bi-directional data delivery with error detection, AR Q , segmentation, role switch and a low-activity mode. An evolution path to point-tomultipoint, requiring additions only in master capable devices. 2006 NokiaS mart S ens or Architecture.ppt / 2006-03-10 / IJ 16. Mimosa Architecture Radio sensor nodeBack-end serverRFID Sensor MSP4304. LEE ASICSSI serverSensorsnanoIPInternetFPGA Digital sensor management (memory map)D M-SPI UART SPI/IIC ABT LEERFID (front end)UMTS G PR SM-SPI1.3.1. Host (N6630) Application space M-APISSISSI(Client)5. RF-module1.(virtual Server)4. LOCOS2. SEMBO MSP430Communication Layer (U-ULIF)SSI serverSymbianMCUSPIADCDevice driversCARTFPGAUART SPI/IIC DADACRadio BBsPOP SPI 3. Sensor-HW16 2006 NokiaDevice driversULIFS mart S ens or Architecture.ppt / 2006-03-10 / IJ2. Sensor-HW 17. Simple Sensor Interface (SSI) protocol A simple protocol for reading smart sensors over, e.g., BT LE E Also provided for R F ID sensor tags Memory map of sensor data on C ompatible with IS O 18000-4 S upport for multiple sensors on multiple devices S upport for data polling or streaming Developed in co-operation with S uunto, Vaisala, Mermit, C E A-LE TI, O ulu University and Ionific Development of the specification keeps backward compatibility (v0.4-) F or specifications, source code and discussion forum, visit http://ssi-protocol.net 17 2006 NokiaS mart S ens or Architecture.ppt / 2006-03-10 / IJ C lient-server architecture Terminal has client software S ensor unit has server software C lient can poll sensors ask the server (O bserver) to stream data to client (Listener) read and modify the configuration of the server C ommands have two forms C apita