Wireless Sensor Based on Bluetooth Technology
Contents
1. eese eene eene 46 7 3 Mountimg instructions sssini iena an Roda e deco qaqa 48 7 4 Component list and cost aes cast tie ace Qum ati ysam S HERE e Rent es 51 7 5 Project milestones nidi a as dd e ted ea ride se ad Ped euet Deis 52 7 6 Wireless Sensor datasheet 2 l u l ete tede etait feet tty 53 RT N 0289 Wireless Sensor Based on Bluetooth Technology 9 In this kind of robotic systems all the sensor devices are closed to the controller less than 2 meters Wires have to go through structure and moving joints This makes wiring quite hard Wiring grounds properly is also a big issue We have to take care of this for avoiding ground loop effects Wireless sensor technology would help It would result in dramatic hardware simplification and would make the whole system more robust 2 3 2 Medical applications Robotic systems are used for medical applications especially for surgical procedures Medical robotics aims at improving the capabilities of physicians to perform surgical procedures Some existing applications are listed here 1 Atypical robot assisted procedure is a biopsy under CT imager control The procedure consists in the following steps o Step 1 taking a CT scan where target is supposed to be located o Step 2 target and entry point identifications are made using CT slices Target is usually be tween 20 and 100 millimeters depth insi2. It is connected to the Bluetooth module for going or leaving the power saved mode micro controller standby mode e UART interrupt handler It receives incoming characters e Main program First of all it initializes the internal registers Then an infinite loop waits for an incoming character a command The command is treated and an answer is sent within the loop The C code is about 1000 lines The file produced is 7 kilo bytes Motorola S Format type and 2 75 kilo bytes on the micro controller flash 3 8 Program running on host A test program running on Microsoft Windows station provides an access to all features available on the module This test program is developed using Microsoft Visual C environment on Microsoft Windows XP Because this is a Console type program it can be ported easily on other operating systems like Linux The program accesses a Bluetooth dongle connected over USB Create File CloseHandle ReadFile WriteFile basic Microsoft Windows functions are used for the USB communication The communication channel number COMX is given by a Bluetooth utility program This utility program pro vides several Bluetooth features discovery mode connecting device which are not implemented inside the pro gram The utility program provides also Microsoft Windows systems features like mounting Bluetooth connec tion channel on a Microsoft Windows COM channel The program consists on two sub programs An argument
3. We consider using a lab power supply for developing the test bed In a second step primary battery will be used in our first experiment But the specification will take into account secondary battery as power supply In fact we do not consider embedding a battery loader So the design does not depend on technology used Both primary and secondary battery are considered as voltage generator The challenge for the sensor is to have the capability for rising up an alert when energy is low Then the strategy is different according to the battery technology Li ion battery output voltage is almost linear with respect to dis charge We do not know how to deal with the primary battery technology 2 9 2 Power saved strategies A major challenge for a sensor device is being awake as many hours as possible Power saved strategies might be activated when possible for extending autonomous period First power saved strategy consists on activating module power saved Most of micro controller chips do have this feature Bluetooth modules seems having this feature too But because of module complexity it is not clear what kind of power saved feature may be activated It might also depend on Bluetooth configuration This has to be investigated Sensor modules usually are intelligent chip with no power saved feature Then an action to switch off modules may be considered The Micro controller might cut power of unused mod ules At the end we shal
4. 1 1 1 1 PC Ix delay i delay ahalog Figure 14 communication protocols top synchronous bottom asynchronous 3 10 Prototype limitations The sensor device main limitation concerns its accuracy RT N 0289 Wireless Sensor Based on Bluetooth Technology 41 4 Conclusion We successfully build a wireless sensor Main features are reported in the document annex ref annex 6 Our contributions are as follows 1 we have reviewed existing research or commercial wireless sensor devices 2 a prototype has been built and successfully tested Therefore research groups have now the opportunity to use the wireless sensor technology within their applica tions The tests performed are relevant and the limitations are clearly identified thus making the integration proc ess clear The prototype developed is not a final or a commercial product The making process was very intuitive Also components and modules placement is clearly not efficient But the final step for getting a usable product is not so high modules have been validated The desired func tionalities have been implemented with success The package must be optimized in order to fit the application The interface board has to be cleaned up and a new version might use integrated technology like CMS compo nents The wireless sensor cost is about 300 euros The purchase list is given in the document annex ref annex 4 A 40 euro
5. N 0289 Wireless Sensor Based Bluetooth Technology 39 5 The receives the analog scan result The resulting bandwidth is about 30 Hertz The asynchronous protocol is as follows 1 The requests for an analog scans 2 The micro controller receives the command 3 The micro controller performs analog scans and sends back the result Scans are synchronized using the micro controller timer thus allowing different output frequencies At the same time the micro controller carries on receiving incoming commands 4 The PC receives the incoming analog scan results 5 When the PC decides to stop it requests the micro controller for stopping sending analog scan results The second protocol uses more micro controller and PC resources because it needs several processes running in concurrent mode It has been successfully implemented on the micro controller and the PC And it should be preferred for applications when the bandwidth is critical The next two figures ref Figure 14 summarize both protocol timings MICRO CONTROLLER FO 1 1 Eg z I I 1 3 fit X E A A F T F i ae Pg Dj Bl S 1 d 9 oN 2 m I i Fog 1 1 1 ES PC pog 1 TIME i delay i I delay ahnalcg T MICRO CONTROLLER 3l h n Ej i H 1 1 o F I oO x 1 E i i B 3 z E 1 I m 3 A 1 1 1
6. P86 26 PS7 SCL P83 FTIOC P56 SDA P82 FTIOB 2 PSS WKPS ADTRG P81 FTIOA M PSA WKP4 POOFTC 2 PS3 WKP3 PS2 WKP2 P51 WKPI PSO WKPO PBO ANO PB1 AN1 PB2 AN2 PB3 AN3 PB4 AN4 PBS ANS ri PB6 AN6 PB7 AN7 Figure 5 H8 3664F general architecture The AE 3664FP board ref Figure 6 is a 40mm x 27mm module based on H8 3664F Renesas micro control ler RT N 0289 Wireless Sensor Based on Bluetooth Technology 27 Please refer to Renesas Hitachi Single Chip Microcomputer H8 3664F Hardware Manual ref 14 for a com plete hardware description Software development tools HEW 2 2 High performance Embedded Workshop from Renesas is a flexible code development and debugging environment for applications target at Renesas microcontrollers It provides an up to date look and feel with all of the features you would expect from a modern development environment The Flash Development Toolkit FDT 2 2 is used for flashing programs on the micro controller HEW GUI al lows FDT access KPIT GNU compiler linker KPIT Cummins proposes an installable GNUHS cross compiler tool chain based on freely available source code from the Free Software Foundation www gnu org to help those who wish to build embedded system applications for Hitachi s H8 series of targets GNUHS is fully integrated inside HEW 3 3 3 Bluetooth module ConnectBlue OEMSPA 13i The OEMSPA13i ref Figure 7 and 16 cB 07
7. controller Unit de recherche INRIA Rh ne Alpes 655 Avenue de l Europe 38330 Montbonnot St Martin France T l phone 33 4 76 61 52 00 T l copie 33 4 76 61 52 52 Wireless Sensor Based on Bluetooth Technology Wireless Sensor Based on Bluetooth Technology Author Herv MATHIEU Research Engineer at INRIA Rh ne Alpes Hardware amp Software systems integration Email herve mathieu inrialpes fr Web home page http www inrialpes fr sed people mathieu Welcome html RT N 0289 Wireless Sensor Based Bluetooth Technology 7 6 1 SeHhSOPDE0VIefS as iri e Pt t e et e d etn e 44 6 2 Micro controller module providers 44 6 3 Wireless sensor providers including Bluetooth amp other RF technologies 44 6 4 Bluetooth chip or module providers 44 6 5 Bluetooth stack providers D L a SS tee u ba e iama 44 6 6 Other Bluetooth related companies nennen enne 44 6 7 Other RE solutions iss ont dre heated Idle metier Oei eee aS 44 6 8 Battery related websites i e cies n reete ae eee eee iere eerie be etg 44 P UD c C us a a haku ak uu ahua aa uu akaun aaa uyu kaa days qapas 45 7 1 Interface module schematic 2 ee 45 7 2 Interface Module PCB component and net lists
8. given when program is called activates one of the sub programs The first sub program is used for measuring communication time It is described within the embedded pro grams section The second sub program consists on a menu providing functionalities described within the How does the sensor device work section RT N 0289 Wireless Sensor Based on Bluetooth Technology 37 The first objective was to contain the whole system in a small box We succeed with a 55mm x 55mm x 42mm box The total weight is 120 grams The weight distribution is reported in the next table ref Table 10 Name Weight gram Battery 48 Micro controller module 9 Bluetooth module 5 Box 35 Sensor module 3 Interface module 15 Misc wires insulator 5 Total 120 Table 10 weights The second objective concerned the power consumption The following table ref Table 11 reports the power supply measurements performed in the different device configurations The lines match the incrementally build ing steps First the micro controller is alone then the sensor is added then the Bluetooth module is connected At the end the whole system including the LEDs and the auto power off feature is tested At the same time we tested the power saved modes It is reported as Idle or Stand by for the micro controller and Not Con nected Connected or Stop Mode for the Bluetooth module RT
9. in network and communication research programs OEM products usually are based on non Bluetooth technology Research groups working on this product class claim that the Bluetooth protocol is too complex and too slow during the connecting process Therefore they choose RF technologies which could provide an easier access Products really designed to be a sensor device are end products Some of them are based on Bluetooth technol ogy Some companies claim that Bluetooth technology makes products easy to integrate because of wide use of this technology Any PDA or Laptop allows connecting you Bluetooth based products do not really fit the specification described in the target applications section their dimensions are generally too wide They are designed to be used with a particular sensor not with the one you would like to use At the end we get the following conclusions 1 This is the beginning of the wireless sensor history 2 It makes sense to design a home made wireless sensor 3 Among wireless technology used in projects or products reviewed Bluetooth technology is a good can didate in our context Bluetooth technology is available on existing computer via dongles and it is ac cepted by a lot of industrial companies Debug phase and experiment integration would benefit Two documents help considering Bluetooth technology as a good candidate for a wireless sensor device The first document ref 6 described how a Bluetooth based
10. is useful to know what is reachable in terms of final products However you do not know how company did it the Commercial product term implies usually a secret process We list the electronic modules which can be candidate for a wireless sensor device That implies RF Radio Frequency modules micro controller modules energy technology and sensor devices e We report uncertainties about technology and functionality that should be cleared up within a prototype pro ject The second phase is related to a proof of concept prototype The goal of this prototype is to know if the concept as defined during the first phase works in real We report how we successfully built a wireless sensor Aspects presented are as follows 1 About the test bed itself specification hardware description embedded software purchased list and cost are given 2 About the development environment tools for programming and debugging the test bed and experiments per formed are described 3 We report also the experiments results and discuss the prototype Off the shelf modules have been bought when existing We tested the concept by using a dual axis inclination sensor We chose this sensor because we had a previous experience with it When designing the test bed we tried as much as possible to get close to a usable product Therefore we took care of the sensor dimensions the power consumption etc Keywords sensor MEMS wireless Bluetooth micro
11. module was built The second document ref 7 presents an interesting overview of Bluetooth based sensor architecture 2 5 Wireless sensor device architecture We decide to specify the sensor device choosing off the shelf electronic modules when possible Of course sen sor compactness is not optimum nor power consumption but time development will be reduced significantly The project goal is clearly not developing a 2mm x 2mm x 2mm sensor device as Berkeley final goal within smart durst research project We do not have access to MEMS technology as developer and people involved in this project are not so many The project goal is developing a hand size 50mm x 50mm x 50mm sensor device This wireless sensor device consists on a box containing 1 a sensor based board 2 a micro controller card 3 a wireless communication card 4 and a power supply stage The following figure ref Figure 1 presents a device architecture based of functional blocks Most of the blocks are also materialized with a electronic module RT N 0289 Wireless Sensor Based Bluetooth Technology 13 Power supply energy this part really depends on other modules During development phase an ex ternal power supply has to be provided first An exhaustive calculation for power consumption has to be done Then a technology shall be chosen Anyway about technology Li ion battery is optimum in terms of power versus weight Primary battery migh
12. process In other words we explain why wireless sensors were so interesting RT N 0289 Wireless Sensor Based on Bluetooth Technology 21 3 Parttwo proof of concept prototype Figure 3 the prototype 3 1 Introduction The objective for the test bed experiment consists on validating wireless sensor concept as defined in the first part overview Roughly it consists on packaging inside a small box a sensor in order to evaluate its communi cation performance over a wireless channel and its power consumption In practice test bed experiment consists on a remote dual axis inclination sensor ref Figure 3 This document is composed of following parts e Hirst it gives how the sensor device works e Then the off the shelf modules used in test bed are detailed e It reports also the interface module specification This module has been developed for inter connecting the off the shelf modules e The embedded software and the development environment are described e Energy and packaging specifications are presented e At the end the results concerning power consumption and communication experiments are reported This document may be considered as e Anelectric and mechanical manual for building a sensor device RT N 0289 Wireless Sensor Based on Bluetooth Technology 23 General comments about monitor are e lt error gt may replace ok or local time when error occurs on micro controller module program e During th
13. supply is used the regulated 5 Volts may be used as output for supplying other modules The OEMSPA13i Bluetooth module needs a 3 6Volts 100mA power supply Intra module voltage is 3 0 Volts The MXR2999 sensor module needs a 5Volts 4mA power supply At the end the power consumption calculation gives 5 Volts 154 milli Amperes for the three off the shelf mod ules The on board 7805 is not strong enough for supplying all modules For the very first experiment we de cided to add a 5 Volts regulator 7805 on the interface module In fact experiments show us that power consumption never get over 90 milli Amperes So we give up using an additional regulator component 3 4 0 Power saved mode The micro controller and the Bluetooth module have such a power saved mode The strategy for getting this mode is presented in the software section RT N 0289 Wireless Sensor Based Bluetooth Technology 31 3 5 2 A mechanical interface for screwing Bluetooth module two 2 5 millimeters diameter through holes 7 1 connector for the Bluetooth signals two pins for the Bluetooth module power supply three pins connector for the Bluetooth module LEDs output and two pins for the RS232 communication An interface to the micro controller module two 2 54 millimeters pad two rows 13 columns power stage two pins connector for the battery and a static relay for the software control of the power two resistors coming with the stati
14. 01 01 technical module id is a small size Bluetooth module based on the Infineon former Ericsson Microelectronics PBM 990 80 baseband controller and the PBA 313 05 OdBm radio The PBM 990 80 has on chip SRAM and FLASH stacked in the same package The main features are short range 0 dBm logic level and RS232 internal antenna 3 3 6 VDC power supply The module state modes are either the Configuration mode or the Data mode The Configuration mode is used for configuring the Bluetooth parameters This configuration may be achieved using AT commands ref 17 or ECI protocol ref 16 A Microsoft Windows wizard based on AT commands allows configuring part of the Bluetooth parameters Other parameters must be modified using AT Commands or ECI protocols directly The Data mode is a totally transparent serial channel mode Each character sent or received goes through the Bluetooth module Figure 7 OEMSPA13i ConnectBlue Bluetooth module All OEMSPA13i IO pins except RESET are located on a dual 2 millimeters connector ref Table 8 Hard ware RESET is located on J3 connector pad on PCB RT N 0289 Wireless Sensor Based on Bluetooth Technology 29 e Serial configuration is 19200 bauds 8 bits 1 bit stop no flow control e Device name inria ra ws 001 e Always connected feature disabled Software layers commands are a set of ASCII commands recognized by the Bluetooth modu
15. 155 0249 0803 VAINRIA INSTITUT NATIONAL DE RECHERCHE EN INFORMATIQUE ET EN AUTOMATIQUE Wireless Sensor Based on Bluetooth Technology Herv MATHIEU N 0289 December 2003 THEME 3 apport technique INRIA RHONE ALPES Wireless Sensor Based on Bluetooth Technology Herv MATHIEU herve mathieu inrialpes fr Theme 3 human computer interaction image processing data management knowledge systems Technical report n 0289 December 2003 56 pages Abstract This document discusses a project which aimed of building a wireless sensor device The objective of the project is to master a new sensor approach Target applications are robotic systems including medical robots This project is decomposed in two phases These two phases are reported in the main parts of this document overview and proof of concept prototype The first phase deals with concept and general architecture The following actions take place e We present target applications and the kind of sensor that can be used in them e Existing similar research projects were investigated Usually documents related to these projects are open documents That means that one has an idea about how work has been done and what can be done limits in terms of technology The drawbacks are that final products do not exist or that they are not described in any document e We investigated also off the shelf commercial wireless sensors This class of information
16. I The Host Controller Interface HCI provides a command interface to the Baseband Link Con troller and Link Manager and access to hardware status and control registers L2CAP Logical Link Control and Adaptation Protocol L2CAP supports higher level protocol multiplexing packet segmentation and reassembly and the conveying of quality of service information RFCOMM The RFCOMM protocol provides emulation of serial ports over the L2CAP protocol The protocol is based on the ETSI standard TS 07 10 SDP The Service Discovery Protocol SDP provides a means for applications to discover which ser vices are provided by or available through a Bluetooth device It also allows applications to determine the characteristics of those available services First profiles defined are Qo c tA s oO generic access profile SDAP service discovery application profile CTP cordless telephony profile IP intercom profile SPP serial port profile HP headset profile DNP dial up networking profile FP fax profile LAP LAN access profile GOEP generic object exchange profile OPP object push profile FTP file transfer profile SP synchronization profile RT N 0289 Wireless Sensor Based Bluetooth Technology 19 The document ref 10 gives an interesting overview of battery technology The following websites ref web34 web35 web36 and web37 describe existing products
17. R3 480 ohms 1 e 1 I R4 220 ohms ER ENERGY 1 WIRELESS SENSOR TESTBED Figure 10 schematic layout RT N 0289 Wireless Sensor Based on Bluetooth Technology 33 TOP VIEW without cover LEFT SIDE VIEW 35 BATTERY SENSOR BATTERY MICRO CONTROLLER MICRO CONTROLLER s INTERFACE MODULE INTERFACE MODULE BLUETOOTH BLUETOOTH 1 Figure 12 module packaging The modules mounting instructions are given in the document annex ref 3 The sterilization process is quite easy with a hermetic plastic box Only the push button and the diagnostic led could induce problems Fortunately theses components are commonly used in medical applications For the pro totype we did not take into account sterilization process and we choose standard components 3 7 Embedded programs Before talking about the final version of embedded program let describe briefly the test procedures we per formed These programs implement incrementally features Hello World learning development tools From the hardware point of view the micro controller is plugged on the development board H8 Tiny Board TERA2 A RS232 cable connects development board to a PC running Microsoft Windows XP The developed program uses the H8 3664F RS232 hardware
18. at kind of Bluetooth function alities we need A full control of the Bluetooth stack means hundreds of code lines But a minimum con figuration is done by only five code lines 2 8 Bluetooth technology Note a special award for the http www palowireless com infotooth tutorial website ref web30 This is clearly the best website we found about Bluetooth technology The following websites ref web15 web16 web18 web28 and web29 have been also read for this part 2 8 14 Technology Overview Bluetooth is of course not the only wireless technology available Other technologies like WLAN HYPERLAN DECT exist The main features of the Bluetooth technology are short range RF lt 10 meters for 1 milli Watt version low cost up to 8 connected nodes together piconet It fits projects working on local sensor devices networks A large majority of the project reviewed uses either Bluetooth technology or wireless technologies based on the same RF specification 2 4 GHz spread spectrum frequency hopping Bluetooth is the codename for a technology specification for low cost short range radio links between mobile PCs mobile phones and other portable devices and connectivity to the Internet Unlike many other wireless standards the Bluetooth wireless specification includes both link layer and applica tion layer Radios that comply with the Bluetooth wireless specification operate in the unlicensed 2 4 GHz radio spectrum ensu
19. c relay A connector for the dual axis sensor Power Ground Xout and Yout signals Four LEDs coming with four resistors Three of them are dedicated to the Bluetooth module LEDs The fourth LED is used as a micro controller status display Diagnostic LED A jumper allows powering or not the Bluetooth LEDs This jumper may be installed for debug purpose Removing the jumper pro vides energy saving A 74HCT08 4 AND logic chip for adapting the 3 Volts CMOS outputs Bluetooth side to the 5 Volts CMOS inputs micro controller side Two extension connectors for the future uses analog inputs digital inputs and outputs power and ground Interface module design The next figure ref Figure 10 represents the interface module schematic The extensions mentioned in the above section are not represented Pin out is given except for VCC and GND signals 1 1 Bz Ki Ba pLHETOOTH BREENLED e R2 REE TED 1 MODULE ver Bar 1 6 1 1 Sue i GND qJ fig Rl DTAGNOSTIC F Eun 1 74HCTO 1 4 BXD 1 1 GND 1800 TXD MISC CN220 CN224 CN2 25 MICRO jp X OUT CND CN29 3 CONTROLLER SENSOR MAIN POWER SUPPLY PRS Sk AO BREE cural Your ES CN2 10 CN 23 POWER CONTROL E _L PUSHBUTTON 1 I 1 VEC R 1 1 83 1 1 GND i L GND LED 2im4 125 ils cun LBA110SmA ap i LBA110 i 1 Rl 2kohms I R2 lkohuus
20. de the body The skin entry point represents the hole where the linear tool needle catheter or bone drill will be inserted This two point identifica tion gives three parameters in case of a linear tool two angles for tool orientation and one dis tance depth for insertion o Step 3 manual or robot assisted placement typically includes the following three decoupled tasks 1 touch down with the tool tip on the entry point 2 orient the tool by pivoting around the skin entry point and 3 insert the tool into the body along a straight trajectory Performing this robot assisted procedure requires registration of robot and imager Registration process consists in finding a 4x4 matrix This matrix represents how coordinates change between imager coordi nate system and robot coordinate system Registration requires several points of interest which are paired in both coordinate systems Pairing is always a critical phase Adding sensors improves the registration process For instance some of the points of interest described above allow calculating what the vertical direction for both coordinate systems is An inclination sensor gives directly this information Therefore less points of interest have to be paired This helps reducing matrix resolution complexity and so makes the registration process more robust Adding inclinometer sensor on a robot improves also safety It can be used as redundant encoder be cause it gives information about robo
21. e 5 e Plug battery using the battery clip e Insert the battery then the insulator plate e Insert the devices Bluetooth module Interface module Micro controller module e Screw the top panel on the box using the four screws i 10 mm 75 mm Push Button i777 m Sensor O G Q 5 mm 10 mm imi au d 2 E a T Area where the thickness must be reduced TOP PANEL BOX O Q Dashed lines represent components shape Annex 3 Figure 1 top panel left outside right inside LED FUSH BUTTON SENSOR LEB R 2 kohrmis R 460 Ohms Annex 3 Figure 2 interface module PCB placement RT N 0289 Wireless Sensor Based on Bluetooth Technology 7 4 Component list and cost We list in the following table any software and hardware items used for building the wireless sensor 51 Name Company Reference Distributor Reference Price euros Micro controller mod Renesas AE 3664FP Microtronique AE 3664FP 39 ule ref web08 H8 tiny board Microtronique H8 development board Microtronique 30 Software H8 Renesas HEW 22 0 Flash Toolkit Renesas FDT 22 0 GNU H8 C KPIT wingnuh8v0303coff 0 BlueTooth Module ConnectBlue OEMSPA13i Eurodis ref 158 web21 Software ECI API ConnectBlue CB BTEDK01 Eurodis 305 Sensor MEMSIC mxr2999m Eurodis 20 Sensor PCB MEMSIC MXEB 002 L Eurodis Interface module INRIA Inria ws Te
22. e analog scan stream mode F the timer frequency is changed from 4 Hertz to 122 Hertz Therefore checking local time before during after the analog scan stream mode may induce time discontinuities e Except for the stream mode the communication is initiated by host computer So a very simple protocol based on send a command wait for answer may be used The stream mode makes the host communi cation state machine a bit harder Multi threaded processes might be programmed for avoiding conflict ing returned messages When the watchdog is enabled default mode the module turns off its power if no command is received during a programmed period In details a timer interrupt handler decrements a counter When an incoming command occurs the counter is updated with a predefined value When the counter reaches zero the program turns off a digital output thus cut ting the power supply Remark The power supply will be turned off even if a client is connected Criteria used deals only with incoming commands 3 3 Otff the shelf devices description 3 3 1 Sensor module MEMSIC mxr2999m The MXR2999 ref Figure 4 and 11 is a low cost dual axis accelerometer fabricated on a standard submi cron CMOS process The MXR2999 measures acceleration with a full scale range of 1 g and a sensitivity of 1000mV g at 25 C It can measure both dynamic acceleration e g vibration and static acceleration e g grav ity The MXR2999 design is ba
23. ending on Bluetooth configuration Other sensors like pressure temperature or humidity have the same features but they are not considered for the moment Sensors like CMOS video camera are much more complex They need much higher resources Micro controllers involved in this class of sensor are usually 32 bits The communication channel bandwidth required is over one mega byte per second MEMS sensors are an emergent technology They have low power consumption and are very small Their preci sion is now relevant for most applications How to define MEMS technology Extract from www memsnet org ref web06 Micro Electro Mechanical Systems MEMS is the integration of mechanical elements sensors actuators and electronics on a common silicon substrate through micro fabrication technology While the electronics are fab ricated using integrated circuit IC process sequences e g CMOS Bipolar or BICMOS processes the mi cromechanical components are fabricated using compatible micromachining processes that selectively etch away parts of the silicon wafer or add new structural layers to form the mechanical and electromechanical de vices 2 6 2 Extensions to no sensor devices The general architecture shows a communication module plugged with a micro controller module We may con sider using theses bricks to make another king of device for instance a remote controller device Powering a low power laser beam is an example This ki
24. l consider the capability to switch off the whole system This implies 1 to get an external action for switching on the system for instance a push button 2 the capability to switch off the module by using a button or by using a programmed watchdog process This strategy step is important for applications meaning The wireless sensor device would not be an autonomous sensor device anymore It is clearly a limitation for some applications It has to be considered as last chance for saving energy 2 9 3 To be demonstrated with a prototype e Anexhaustive power consumption calculation must be done Depending on the battery technology used we will estimate how long a wireless sensor device can be powered life cycle Different power saved strategies might be tested e The capability for avoiding power supply failure when the battery charge is empty e Batteries are usually packaged in a metallic box It could disturb wireless transmission This has to be evaluated 2 10 Packaging The packaging is a big issue but it might be finalized only when all internal parts will be defined The general requirements for packaging are e Hand size container box sizes must be less than 50mm x 50mm x 50mm Sterilizable e Radio Frequency free way compatible It implies avoiding metallic parts Most of plastic boxes are suitable 2 11 Conclusion overview part We present target applications where wireless sensor could improve dramatically the
25. le An escape sequence sent over serial line to Bluetooth module changes its internal mode It switches from data mode to commands mode Then the host configures the Bluetooth module using AT commands Data mode is switched back using another specific AT command The ECI protocol ref Figure 9 is delivered as a C library It runs on the host with an interface towards all the Bluetooth functionality embedded in the Serial Port Adapter The ECI protocol is a lightweight protocol It pro vides access to the profiles GAP SPP DUN and LAN as well as some other miscellaneous functions It supports true multi point ECI protocol is delivered with source code and so can be compiled on different target po Host I Ann limi f 1 PN PTS I i pplication i i LI LI 1 ECI protocol Serial Port Adapter i GAP SPP Service i DUN Search i 1 Figure 9 ECI protocol architecture 3 4 Energy The original idea was to design an always on wireless sensor In other words the wireless sensor is powered when battery is connected and stops working when battery is discharged 3 4 4 Power consumption calculation based on datasheets The H8 3664F micro controller needs a 5Volts 50mA power supply 7805 5Volts 150mA regulator is located on this module Either a regulated 5Volts 50mA or 7 20Volts is used for powering the module When 7 20Volts power
26. leph Inria ws 7 Static relay CLARE LBA110 Radiospares 8 Logic And Texas Instru 745 A HCT08 Radiospares 221 0883 0 7 ment LED 2 mm x4 Dialight 551 1 123 07 Radiospares 197 126 0 61x3 Clips for battery Radiospares 172 5996 0 5 Connector I O x2 Phoenix Con MPT 0 5 8 2 54 Radiospares 220 4327 2x2 tact Connector Bluetooth Radiospares 180 6578 5 2 mm pitch Push button Cube box Radiospares 281 6936 3 USB Bluetooth dongle 40 The prototype price is about 300 euros The only device you need to work with the sensor device is a Bluetooth dongle connected to a PC A dongle can be purchased in any computer accessories store Its cost is about 40 euros RT N 0289 Table purchase list Wireless Sensor Based on Bluetooth Technology 53 7 6 Wireless Sensor datasheet The Wireless sensor device provides remote sensing in an efficient way No physical connection is necessary Any off the shelf Bluetooth dongle connected to a PC allows interfacing this device Dimensions 55mm x 55mm x 42mm cube box made in ABS plastic Weight 120 grams including 48 grams for battery Energy e Primary battery type PP3 9 Volts e Autonomy better than one month depending on day by day use e Auto power off feature Technologies used e Bluetooth module based on Infineon chips Power Class e 16 6165 micro controller from Renesas formerly Hitachi H8 3664F e MEMS Micro Electro Mechanical Systems dual axis incli
27. ms for a wide variety of applications including machinery health seismic monitoring or impact detection They instrument sensors with Bluetooth interface Products are clearly end products not for OEM Millennial Net ref web13 produces low power wireless sensors These products are used in industrial auto mation building automation supply chain management automatic meter reading security and other low data rate applications The company s primary product is the i Bean It combines analog and digital interfaces a radio transceiver and a microcontroller for sensor signal processing control and networking Millennial Net uses a portfolio of radio technologies including ultra low power narrowband solutions as well as IEEE 802 15 4 wire less personal area network WPAN components Milennial Net was created in year 2000 and traces its roots to MIT Sensicast Systems ref web11 develops and markets low power battery operable wireless sensor network solutions for the commercial industrial agricultural and security industries Star product is H900 Wireless Sen sorNet System It is based on 900 MHz RF band Sensicast Systems Inc was created in 2002 One can notice that most of the companies were created in the last four years and are located in USA They are working together with world class universities Some products are based on Bluetooth technology others on 900 MHz or 2 4 GHz RF bands Open products OEM market are used
28. nation sensor Performance e 60 degrees dual axis inclination measurement e Resolution better than 0 5 degree arc e Bandwidth better than 100 Hertz e Distance between PC and device up to 10 meters Bluetooth class II Software development C language e Micro controller is ready for working Source codes are available Renesas software development toolkit is free Therefore embedded program can be modified very easily for fitting application e A Windows Console type program with full device functionalities support is available as source code Medical application e Sterilizable package e Read in the news a Bluetooth based device received a FDA approval A technical report written in English includes a detailed hardware and software description Other packaging can be designed easily Extensions to other sensors are possible thanks to the eight analog inputs available on the micro controller Extensions to other devices including LASER or motor remote controllers are possible thanks to digital inputs and outputs available on the micro controller Copyrights INRIA 2003 RT N 0289
29. nd of device is controlled by a simple digital output This makes it easy to integrate RT N 0289 Wireless Sensor Based Bluetooth Technology 15 We report in the next table ref Table 2 modules which fit the specification MICROCHIP PIC micro control ler family is a very interesting candidate for this kind of application But we did not find any integrated module with mandatory dimensions Company Model Micro Size Power supply IO Software Dev Cost controller mm Tool euros PHYTEC phyCORE Atmel 60x53 3 3 Volts 110 AD 8x11bit C compiler 295 ref web07 ARM7 AT91M55800A mA typ Ethernet www keil com DA 2x10bit PHYTEC phyCORE ST10 60x53 5 Volts 110mA AD 10bit C compiler 165 ref web07 5 10 168 typ www keil com RENESAS Module H8 3664F 40x27 5 Volts 50mA AD 8x10bit GNU C com 60 ref web09 AE3664 typ piler www kpit com Table 2 micro controller modules 2 7 3 To be demonstrated with a prototype e The analog inputs dynamic range has to be consistent with sensor dynamic range e The power consumption must be really low For instance power management must be easy to imple ment e flash memory must be large enough for the developed program This point is crucial but the prob lem is that we are not able to know in advance what will be the final compiled code size For instance concerning the Bluetooth module associated code its size depends on wh
30. of them is an incoming interrupt e An interrupt handler attached to an IRQO input pin sets 1 or resets 0 a flip flop semaphore depending on the interrupt edge is rising or falling The main C function is based on an infinite loop waiting for an incoming command over RS232 A test on a semaphore state has been added into this loop The follow ings actions happen within a session 1 At power on the micro controller does its initialization then calls the sleep function and en ter standby mode 2 When a client connects the Bluetooth module wakes up and enters the connecting mode Then GREEN LED signal output goes to high state and the micro controller interrupt rises up due to a rising edge input This makes the micro controller leaving standby mode And during the next loop program the sleep function will be bypassed thanks to the semaphore state 3 When the client disconnects the Bluetooth module switches GREEN LED signal output to low state then it enters stop mode Micro controller interrupt rises up due to a falling edge input The semaphore changes its state and during the next loop program the sleep function will be called Thus makes entering the micro controller to standby mode Final program The final program consists on a C program with the following parts e Timer interrupt handler it manages local time watchdog and synchronous analog scans requests e External interrupt handler
31. reless Sensor Based Bluetooth Technology 47 Net Connections 1 GND BAT 1 LBA 4 LD 2 S 1 BT 1 HCT 7 CN1 1 2 25 26 CN2 1 2 26 JP 2 IO 1 2 VCC 5Volts R3 1 S 2 BT 2 HCT 14 CN1 23 IO 2 3 BAT BAT 2 PB 1 LBA 6 4 PB 2 R4 1 LBA 7 5 POWER LBA 8 5 CN1 24 IO 3 6 R4 2 LBA 3 7 LBA 1 R3 2 8 PWR CTL LBA 2 CN2 10 9 LED DIAG CN2 9 R1 1 10 R1 2 LD 1 11 JP 1 LR 2 LG 2 LB 2 12 R2R 2 LR 1 13 R2G 2 LG 1 14 R2B 2 LB 1 15 LED_R R2R 1 BT 5 16 LED G R2G 1 BT 6 HCT 1 2 72LED B R2B 1 BT 7 18 RXD CN2 24 BT 3 TXD for the Bluetooth module side 19 TXD CN2 25 BT 4 RXD for the Bluetooth module side 20 IRQO HCT 3 CN2 20 21 ANO ANA 1 CN1 10 22 ANA 2 CNI 9 23 2 ANA 3 CN1 8 24 AN3 ANA 4 CN1 7 25 AN4 ANA 5 CN1 3 26 AN5 ANA 6 CN1 4 27 AN6 ANA 7 CN1 5 28 AN7 ANA 8 CN1 6 29 IRQ2 IO 4 CN2 21 30 IOO IO 5 CN2 11 31 I01 IO 6 CN2 12 32 102 IO 7 CN2 13 33 TMOW IO 8 CN1 20 Table net list RT N 0289 Wireless Sensor Based Bluetooth Technology 49 e Screw the Bluetooth module on the interface PCB then the Bluetooth connector can be plugged on the Blue tooth module ref Annex 3 Figure 3 e Screw wires coming from the sensor in the PCB connector ref Annex 3 Figure 2 Final mount ref Annex 3 Figur
32. resource The complete software development tool kit was validated compiler linker flash toolkit On the PC side we use a HyperTerminal application We vali date also the serial cable Timer amp Analog reading using micro controller features From the hardware point of view the micro controller is plugged on the development board H8 Tiny Board TERA2 A RS232 cable connects development board to a PC running Microsoft Windows XP MEMSIC dual axis inclination sensor is wired on the development board H8 Tiny Board TERA2 using the mirrored micro controller connectors With this program we master two of the major micro controller features timer and analog converter Bluetooth module test configuring and testing module RT N 0289 dOL Wireless Sensor Based Bluetooth Technology 35 e new electronic signal has been connected between the Bluetooth module GREEN LED pin and the micro controller IRQO pin In fact this signal goes through a 74HCT08 for electric compatibility The Bluetooth outputs are 3 Volts CMOS the micro controller inputs are 5 Volts CMOS e The GREEN LED signal goes to active mode when a connection occurs It leaves active mode only when the client is disconnected Note that the BLUE LED behavior is almost the same except that the BLUE LED signal flicks during communication e The micro controller goes to standby mode when the function sleep is called It wakes up for different reasons One
33. ring communication compatibility worldwide These radios use a spread spectrum frequency hop ping full duplex signal at up to 1600 hops sec The signal hops among 79 frequencies at 1 MHz intervals to give a high degree of interference immunity Up to seven simultaneous connections can be established and maintained The Bluetooth specification contains the information necessary to ensure that diverse devices supporting the Bluetooth wireless technology can communicate with each other worldwide The document is divided into two sections a Core Specification Volume I and Profile Definitions Volume II Note about power classes Each device is classified into 3 power classes Power Class 1 2 amp 3 e Power Class 1 is designed for long range 100m devices with a max output power of 20 dBm RT N 0289 Wireless Sensor Based Bluetooth Technology 17 vCard vCal OBEX puruwa iiim RFCOMM Host Controller Interface Baseband Bluetooth Radio Figure 2 Bluetooth specification protocol stack Radio The Radio layer defines the requirements for a Bluetooth transceiver operating in the 2 4 GHz ISM band Baseband The Baseband layer describes the specification of the Bluetooth Link Controller LC which carries out the baseband protocols and other low level link routines LMP The Link Manager Protocol LMP is used by the Link Managers on either side for link set up and control HC
34. s Bluetooth dongle allows working with the device from any computer Half of the device price is due to the Bluetooth module This module includes a useful software stack that provides an easy access to all Bluetooth functionalities But the cost can be reduced significantly by using cheaper Bluetooth modules and developing the missing software stack At the end we would get an affordable sensor device Further works will concern 1 getting a more industrial wireless sensor device version then 2 including this new sensor class within applications During this project we mastered a micro controller module based on the H8 3664F RENESAS chip and a Blue tooth module Research teams working in virtual reality and in robotics are now interested for using these bricks in their applications RT N 0289 Wireless Sensor Based on Bluetooth Technology 2003 e 16 Serial Port Adapter 27 Generation User Manual 1 3 ConnectBlue 2003 e 17 Serial Port Adapter 2 Generation AT Commands ConnectBlue 2003 RT N 0289 43 45 Wireless Sensor Based on Bluetooth Technology 7 Annexes 7 1 Interface module schematic 4 Jaquiny jueuinaog WSUS E azg 937 0191 a a34 q31 EM N3349 037 S010Hvv2 QNS EA Svid 37 RDW RT N 0289 Wi
35. sed on heat convection and requires no solid proof mass The MXR2999 provides a ratio metric analog output that is proportional to 5046 of the supply voltage at zero g acceleration The typical noise floor is 0 2 mg 5 allowing signals below 1 milli g to be resolved at 1 Hz band width The inclination measurements X and Y are given for 60 degrees range and at 30 Hertz frequency update The MXEB 002 L ref Figure 4 and 12 is a 26 mm x 19 mm board It is developed by MEMSIC to make easier the integration of the MXR2999 sensor chip The MXEB 002 L pin out is reported in table ref Table 5 E sii Hd LUN ura a up Zura Ri eo Figure 4 MXEB 002 L Basic Board with MEMSIC IC on the side amp MXR2999GL ML Functional Block Diagram RT N 0289 Wireless Sensor Based on Bluetooth Technology 25 8 channels 10 bit A D 37 I O pins 8 x 20mA ports 11 External Interrupts On chip debug port 8 32kBytes ROM 512 kBytes SRAM 32kBytes single supply Flash 2kByte SRAM Flash version only e xl6 bit timer with 4 capture compare e 5V operation 2 x 8 bit timer e 16MHz H8 300H 16 bit CPU core 1 x watchdog timer e 32 kHz sub system oscillator 1 x USART e Wide range of low power operating modes 1xPC e Table 6 H8 3664F main features E HT E P10 TMOW E P11 8 12 14 00 P15 RQI P16 IRQ2 PT7 IRQS TRGV P20 SCK3 P21 RXD P22 TXD P76 TMOV P75 TMCIV P74 TMRIV P87
36. t be considered also The following sections give some details about the technologies listed above For each of them we list what has to be demonstrated with a prototype second project phase 2 6 Sensor 2 6 h What kind of sensors As described in section about target applications sensors of interest are e Accelerometers which are used as inclination sensor too Accelerometer sensor is a member of absolute family sensor It deals with physic laws like gravity field or earth magnetic field This kind of sensor can be easily integrated into the wireless sensor box Therefore packaging and sterilizing are much easier e Force sensor which are usually based on piezo electric technology This kind of sensor has to be at tached to some hardware structure where you need measuring Packaging is a big issue It can not be generic because it depends on structure shape Also it is much harder to sterilize because of separated pieces This kind of sensors has the following common features e Frequency is between 10 and 1000 Hertz e Signal dynamic is between 8 and 16 bits To be consistent with we should choose a 16 bits micro controller and a communication link throughput faster than 16 kilo bits per second In fact most of 8 bits micro controller deal with 16 bits data with no really drop out performance We can notice that Bluetooth bandwidth is over 16 kilo bits sec In fact throughput is between 128 kilo bits sec and 1000 kilo bits sec dep
37. t orientation too Both information coherencies can be checked thus avoiding hazardous robot behavior due to motors encoder dysfunction 2 During a total knee replacement procedure includes machining bones Some robotic systems perform this procedure like ROBODOC from Integrated Surgical Systems ref web01 A typical problem is doing registration between the robot and the patient s body A common registration is based on localiz ers like Optotrack or Polemus from North Digital ref web02 Basically several tracker devices are attached to the body and the others to the robot All tracker devices are seen by the localizer and so they are represented in a unique coordinate system This makes possible registration between the robot and the patient s body The drawbacks for using common localizers are the following 1 tracking failure due to occlusion tracking devices commonly used cameras 2 a bunch of wires around patient due to wired tracker de vices These active trackers versus passive trackers improve precision 3 a large area inside surgery room is dedicated to the localizer system Adding wireless inclination sensor improves procedure It helps on positioning when occlusions occur Mixing tracking and sensor outputs improves precision Hence passive non wired tracker could be considered RT N 0289 Wireless Sensor Based Bluetooth Technology 11 Oceana Sensor ref web10 is a manufacturer of sensing syste
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