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Wireless Sensor Based on Bluetooth Technology

1. 10 2 3 Wireless sensor device architecture si ERR SRE Re i 11 2 6 SODSOE detti a ne ee aed 13 2 6 1 What kind of sensors sise 13 2 6 2 Extensions to no sensor devices ses 13 269 Examples eens teens toi weg ciet e bep RO 14 2 6 4 be demonstrated with a prototype ss 14 2 7 Micro controller module eee ete e E eret OUR 14 2 7 1 Specification senis eee e PRG ERE RE E UR Het 14 2 72 Examples oen M e MUR Ng ei ai RENT 14 2 7 3 To be demonstrated with a prototype ss 15 2 8 Bluetooth technology 2 deett haste AR T REIR 15 2 8 1 Technology Overview DRESD e e ee ri ed ne ede 15 2 8 2 The Bluetooth e Hi Pet eee d e Ee ee e etn 16 2 8 3 Available Bluetooth hardware modules 16 2 8 4 Bluetooth specification protocol stack ss 16 2 8 5 To be demonstrated with a prototype ss 18 2 9 luc CRE 18 2 9 Technologies osserva n e e UR UT lae EE e RU HERR EE eee 18 2 0 2 Power saved strategies 25e uere ima OR tn nn cn ne 19 2 9 3 To be demonstrated with a prototype ss 19 2 10 Packaging ue sco ae o RI Re RENE DEO re nee ete DU RM FOREN REI UR EUR 19 211 Conclusion Overview pa
2. Algorithms Time milli second Test 1 100 analog requests 19200bauds 32 Test 1 100 analog requests 57600bauds 29 Test 2 one request for 100 analog scan 57600bauds 2 2 Analog scan duration 2 Table 12 communication throughput As conclusion The baud rate is not a major issue The transmission is only 10 percent faster when the rate is multiplied by three 57600 bauds is nominal baud rate for final test bed version e The results show that a delay occurs during transmission Further tests must be done for full under standing the transmission model We can suppose that the same delay occurs from PC to sensor device and from sensor device to PC Then the delay calculation gives about 13 milli seconds This is clearly a limitation for the bandwidth communication At the end two communication protocols synchronous and asynchronous are implemented The synchronous protocol is as follows 1 The PC requests for an analog scan The micro controller receives the command The micro controller performs an analog scan The micro controller sends back the analog scan result The PC receives the analog scan result ee INRIA Wireless Sensor Based on Bluetooth Technology 39 The resulting bandwidth is about 30 Hertz The asynchronous protocol is as follows 1 The PC requests for an analog scans 2 The micro controller receives the command 3 The micro controller performs analog scans and send
3. 1 Li De 1 i Application LI 4 Driver L ECI protocol Serial Port Adapter B ov SPP Service DUN Search LAN 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 1 Power consumption calculation based on datasheets The H8 3664F micro controller needs a 5Volts 50mA power supply 7805 5Volts 150mA regulator is lo cated on this module Either a regulated 5Volts 50mA or 7 20Volts is used for powering the module When 7 20Volts power supply is used the regulated 5Volts 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 modules The on board 7805 is not strong enough for supplying all modules For the very first experiment we decided 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 2 Power saved mode The micro controlle
4. ee e A ote eee 41 Bibl graphy edite PNR A Ee RA eh he ed A ARE bee ce i es 42 6 44 INRIA Wireless Sensor Based on Bluetooth Technology 7 6 1 Sensor providers za dns on ee i o tt de itia adam f t ee ads 44 6 2 Micro Controll r module providers sn te rep reet nn ne ren 44 6 3 Wireless sensor providers including Bluetooth amp other RF technologies 44 6 4 Bluetooth chip or module providers ss 44 6 5 Bluetooth stack providers ss 44 6 6 Other Bluetooth related companies seen 44 6 7 Other RE solutions ihre Ete e SET Re ee eee een eli 44 6 8 Battety related web sttes 1 eee Ay EI RE ala RET AURI Een d seite iius 44 TU s eniascet quete re te Of e eie dr eee 45 7 1 Interface module schematic node t ade et dentes 45 7 2 Interface Module PCB component and net lists 46 7 3 Mounting eie le a s 48 7 4 Component list atid COSt ccc Bk oie Sens ee 51 7 5 Project milestones eder eee e Ede FU shed see dave CR EE et e restau 52 7 6 Wireless Sensor datasheets e trial tite UR PER UB P ERE UA Trina 53 RT N 0289 8 Herv Mathieu 2 Part one Overview 2 1 Introduction One of the major problems with robotic systems comes from cables an
5. DIAG CN2 9 RI 1 10 R1 2 LDC 11 JP 1 LR 2 LG 2 LBQ 12 R2R 2 LR 1 13 R2G 2 LG 1 14 R2B 2 LB 1 15 LED R2R 1 5 16 LED R2G 1 6 1 2 17 LED R2B 1 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 0 3 CN2 20 21 AN0 ANA 1 CN1 10 22 ANI ANA 2 CNI 9 23 AN2 ANA 3 CN1 8 24 AN3 ANA 4 CNI 7 25 AN4 5 CN1 3 26 5 ANA 6 1 4 27 AN6 ANA 7 CN1 5 28 AN7 ANA 8 CN1 6 29 IRQ2 IO 4 CN2 21 30 100 IO 5 2 11 31 01 6 2 12 32 102 7 CN2 13 33 TMOW 8 CN1 20 RT N 0289 Table net list 48 Herv Mathieu 7 3 Mounting instructions Part PCB Qt Part other Qt PCB 1 Box 1 Ul DIP socket 14 pts 1 Insulator 1 U2 DIP socket 8 pts 1 PBI Push button 1 U3 U4 Breakaway header 2x13 2 D4 Led 1 Breakaway header 1x2 for shunt 1 Battery clip type PP3 1 T1 T2 Terminal blocks 8x2 54 2 2 5mm x 10mm screws 2 D1 Led Red 1 2 5mm nut 2 D2 Led Green 1 3 0mm washer 2 D3 Led Blue or Yellow 1 Ul 7 08 1 RIR2R3 Resistor 1 kilo Ohms 3 U2 LBA110 1 R4 Resistor 2 kilo Ohms 1 Wire awg24 30mm long 11 R5 Resistor 820 Ohms 1 Wire awg24 70mm long 6 R6 Resistor 460 Ohms 1 Shunt 1 Bluetooth connector 2x10 1 BtM Bluetooth module 1 5 Sensor module 1 MC Micro
6. Table 11 power consumption in different operating modes The two last lines show what the nominal power consumption for using the device is In fact the case Tdle Connected with the whole device can be considered during a transmission phase Indeed we did not no tice any additional current when transmitting We can suppose that the Connected Mode is already a trans mission mode for the Bluetooth technology This has to be investigated in the future As mentioned within the Energy section an auto power off feature was added during the project period At the end the module should be usable without changing the battery for several weeks Of course it depends on how long it is connected highest power consumption configuration The transmission measurement was the third objective During the experiment a program developed on PC Visual C Console application runs as follows 1 Open a USB channel to the Bluetooth dongle it activates a connection between the PC and the wireless sensor 2 Test 1 Runa 100 loops for requesting an analog scan 3 Test 2 Then senda request for 100 analog scans 4 Close the USB channel The analog scan answer message includes the duration for scanning The test was done at 19200 bauds and 57600 bauds micro controller UART configuration On the PC side a USB is used and we do not get any information about baud rate The next table ref Table 12 reports the results
7. e It reports also the interface module specification This module has been developed for inter connecting the off the shelf modules embedded software and the development environment are described e Energy and packaging specifications are presented Atthe end the results concerning power consumption and communication experiments are reported This document may be considered as e electric and mechanical manual for building a sensor device RT N 0289 22 Herv Mathieu A user manual for working with the sensor device 3 2 How does the sensor device work The sensor box is referenced to the sensor itself Therefore the remote sensor device gives the box orientations A typical wireless sensor device session is described with the following states Power on state when powering on the device pushing button the micro controller and the Bluetooth module execute an initialization phase Then they both switch to a power saved mode Connect state is initialized by a master typically a PC instrumented with a Bluetooth dongle It estab lishes a Bluetooth channel between the master and the remote sensor Bluetooth wakes up first and then micro controller wakes up too Communication state the master requests X and Y axis values from the remote sensor Another simi lar function requests a bunch of data thus avoiding communication delays Disconnect state the master closes Bluetooth channel Bluetooth switches fir
8. MPR400 and MICA2 DOT 500 These modules are used in end user and OEM applications ref 4 and 5 All of these modules provide a processor that runs TinyOS developed at Berkeley based code a two way ISM band radio transceiver not Bluetooth and a logger mem ory capable of storing up to 100 000 measurements INRIA Wireless Sensor Based on Bluetooth Technology 11 Oceana Sensor ref web10 is a manufacturer of sensing systems 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 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 wireless 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 industri
9. The second method consists on doing only one request for a bunch of analog scans This makes a big difference in terms of timing because of the transmission delays All measurements are reported in the Experiments and results section Power saved mode Bluetooth side The goal of this program part is switching Bluetooth module to a power saved mode in order to reduce the power consumption It consists on sending over a RS232 channel several AT commands ref Table 9 Within embedded code running on micro controller this program part takes place just after the micro controller initiali zation phase Added lines Comments WaitOneSecond Wait one second for Bluetooth module to wake up after power on PutString Escape sequence for switching to AT commands mode WaitOneSecond Wait one second for Bluetooth module to switch mode PutString AT AMPM 3 1 Configure module for enabling stop mode WaitForResponse Wait until module response PutString AT ADDM Switch back to data mode WaitForResponse Wait until module response WaitOneSecond Wait one second for Bluetooth module to switch mode Table 9 Bluetooth power saved mode commands The Bluetooth mode is now entering the stop mode power saved mode at power on It leaves the stop mode when a Bluetooth client connection occurs It goes back to stop mode as soon as client closes its connection Power consumption was measured Results
10. board for status purpose The mother board is connected to PC via a RS232 cable A Windows wizard program is used for modi fying and saving parameters over the RS232 channel Figure 8 OEM adapter for the OEMSPA 131 Bluetooth module Example of parameters saved on the Bluetooth module Act as server Security disabled Accepting pairing Serial configuration is 19200 bauds 8 bits 1 bit stop no flow control INRIA Wireless Sensor Based on Bluetooth Technology 29 e Device name inria ra ws 001 e Always connected feature disabled Software layers AT commands are a set of ASCII commands recognized by the Bluetooth module An escape sequence sent over serial line to Bluetooth module changes its internal mode It switches from data mode to AT commands mode Then the host configures the Bluetooth module using AT commands Data mode is switched back us ing 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 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 sup ports true multi point ECI protocol is delivered with source code and so can be compiled on different target LI Host
11. bricks in their applications RT N 0289 42 Herv Mathieu 5 Bibliography 1 RT 0243 L armoire de commande du robot bip de bip2000 INRIA Technical Report Baille G rard Di Giacomo Pascal Mathieu Herv Pissard Gibollet Roger July 2000 2 A Minimal Bluetooth Based Computing and Communication Platform ETH Technical Note Jan Beutel Oliver Kasten May 2001 3 First experiences with bluetooth in the smart its distributed sensor network Swiss Federal Institute of Technology Oliver Kasten and Marc Langheinrich 2001 4 A wireless embedded architecture for System Level Optimization UC Berkeley Technical Report Jason Hill and David Culler 2002 5 Wireless Sensor Networks for Habitat Monitoring Intel Corporation University of California at Berkeley College of the atlantic AlanMainwaring JosephPolastre RobertSzewczyk DavidCuller JohnAnderson 2002 6 Bluetooth Prototype Tag Telenor R amp D Note Tore Syversen 2001 7 Bluetooth Based Wireless Sensor Networks Implementation Issues and Solutions Applied Research Lab Ericsson Ireland Srdjan Krco 2002 8 Sourceless Human Body Motion Capture LETI CEA Grenoble France David Fontaine Dominique David Yanis Caritu 2003 9 Pen like natural graphic gesture capture disposal based on a micro system Department of Systems for Information and Health CEA L ti Grenoble C dric Joguet Yanis Caritu Dominique David 2003 10 Batteries et chargeurs Techno
12. controller module 1 Table components list To machine e The top panel thickness may be reduced for improving push button and led accessibility ref Annex 3 Figure 1 battery clip length is Imm too wide for the box So the inner box width must be enlarged to fit a rape tool can be used for removing several board guides No figure Drill one through hole on top panel box for the push button ref Annex 3 Figure 1 Drill one through hole on top panel box for the led ref Annex 3 Figure 1 Drill one through hole in PCB for screwing Bluetooth module No figure Cut a 50mm x 35mm insulator plate Cut a 40 mm x 15 mm insulator plate Glue both plates with a 90 de grees angle Resulting system must bind the battery inside the box ref Annex 3 Figure 4 Mounting instructions for the interface PCB ref Annex 3 Figure 2 e Solder 7 wires 30mm for connecting the PCB and the Bluetooth connector 2mm 2x10 ref Annex 3 Figure 2 Solder 2 wires 70mm for connecting the push button to the PCB no polarity Solder 2 wires 70mm for connecting the led to the PCB caution to polarity Solder 2 wires 70mm for connecting the battery clip to the PCB caution to polarity Solder the components located in table on the left column on the PCB About the sensor e Solder 4 wires 70mm on the sensor card VCC GND YOUT ref Annex 3 Figure 2 To glue ref Annex 3 Figure 1
13. e Glue push button on top panel box Glue led on top panel box e Glue sensor card on top panel box To plug ref Annex 3 Figure 2 e Plug the shunt if needed e Plug the 74HCT08 chip e Plug the LBA110 chip e Plug the micro controller card Screwing INRIA Wireless Sensor Based on Bluetooth Technology 49 e Screw the Bluetooth module on the interface PCB then the Bluetooth connector can be plugged on the Bluetooth 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 Figure 5 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 i10 mm 7 5 mm Push Button EH 1 T Bie 7 Sensor Mais 1 1 mou os Diagnostic led Area where the thickness must be reduced TOP PANEL BOX Q O Dashed lines represent components shape Annex 3 Figure 1 top panel left outside right inside LED PLUSH BUTTON SENSOR LED R 2 k hrns R 460 Ohms Annex 3 Figure 2 interface module PCB placement RT N 0289 50 Herv Mathieu BLUETOOTH MODULE 5 0000080000 BLUETOOTH COWNECTOR OOO N INTERFACE MODULE P
14. each joint for providing absolute position and inclination sensors are used for global positioning The actual version of the biped robot implements sensors in a conventional method i e connecting two wires for power supply and one or two wires depending on single ended or differential mode for signal INRIA 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 through structure and moving joints This makes wiring quite hard Wiring grounds properly is also 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 A typical 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 inside the body The skin entry point represents the hole where the linear tool nee
15. lt a7 gt lt ok gt n r Analog scan channels 4 5 6 7 x 100 T lt f gt lt ok gt n r Request synchronous analog scans 20 ms lt gt lt a0 gt lt a7 gt lt ok gt n r Sending synchronous analog scans E lt F gt lt ok gt n r Stop sending synchronous analog scans d lt d gt lt status gt lt ok gt n r Request for digital input status 0 1 lt o gt lt ok gt n r Turn on 1 digital output lt O gt lt ok gt n r Turn off 0 digital output lt w gt lt value gt lt ok gt n r Request for power off watchdog time out value second W lt W gt lt current state gt lt ok gt n r Enabled 1 Disabled 0 auto power off watchdog toggle flag g lt s gt lt ok gt n r Switch off module b lt b gt lt ok gt n r Bluetooth AT command configuration for stop mode v lt t gt lt time gt lt ok gt n r Current local time 0 65535 1 second 1024 T lt T gt lt current state gt lt ok gt n r lt local time gt 1 replaces lt ok gt 0 within messages toggle flag tv lt v gt lt version gt lt ok gt n r Return monitor version m lt m gt lt gt lt ok gt n r Command list menu Other lt gt lt gt lt ok gt n r Command list should not be used Table 4 commands tags INRIA Wireless Sensor Based on Bluetooth Technology 23 General comments about monitor are e error may replace lt ok gt or local time when error occurs on micro controller module program e During the ana
16. max output power of 20 dBm e Power Class 2 for ordinary range devices 10m devices with a max output power of 4 dBm e Power Class 3 for short range devices 10cm devices with max output power of 0 dBm What is a piconet a collection of devices connected via Bluetooth technology in an ad hoc fashion A piconet starts with two connected devices such as a portable PC and cellular phone and may grow to eight connected devices All Bluetooth devices are peer units and have identical implementations However when establishing a piconet one unit will act as a master and the other s as slave s for the duration of the piconet connection They all share the same physical channel defined by the master parameters clock and BD ADDR 2 8 2 The Bluetooth Name The Bluetooth name itself comes from the 10 century Danish Viking King Harald Blatand Bluetooth in Eng lish who united and controlled Denmark and Norway hence the inspiration of the name by uniting products through Bluetooth Harald apparently enjoyed eating Blueberries to such an extent that his teeth were stained blue 2 8 3 Available Bluetooth hardware modules When integrating Bluetooth technology into an application you should consider purchasing a Bluetooth module It is clearly not reasonable developing a home made electronic module A Bluetooth module is a small card about 30mm x 20mm x 4mm it contains few components including a Bluetooth chip Only few Blueto
17. on the Bluetooth module mastered October 2003 Tests about the communication performance performed on the whole module October 2003 Measurement of the power consumption performed on the whole module October 2003 Write documentations overview amp prototype October 2003 Bluetooth firmware upgraded October 2003 Purchase additional micro controller modules October 2003 Interface module design updated CAD November 2003 Auto power off feature added November 2003 First packaging November 2003 Final tests November 2003 Final document Table project milestones INRIA 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 Bluetooth module based on Infineon chips Power Class II e 16 bits micro controller from Renesas formerly Hitachi H8 3664F e MEMS Micro Electro Mechanical Systems dual axis inclination sensor Performance e 60 degrees dual axis inclination measurement Resolution better than 0 5 degre
18. 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 N 0289 38 Herv Mathieu Hardware Status Power 9 Volts mA H8 3664F Idle 28 H8 3664F MEMSIC Idle 30 H8 3664F MEMSIC BT Idle Not connected 60 H8 3664F MEMSIC BT Idle Connected 80 H8 3664F MEMSIC BT Idle Stop Mode 35 H8 3664F MEMSIC BT Stand by Stop mode 15 H8 3664F MEMSIC BT LED POWEROFF Idle Connected 90 H8 3664F MEMSIC BT LED POWEROFF Stand by Stop mode 19
19. 131 ConnectBlue Bluetooth module All OEMSPA 131 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 28 Herv Mathieu J1 Pin Pin Name Signal Name Signal Level Type Number 1 2 VSS GROUND GROUND 3 4 VCC POWER 3 3V 6V 5 RS232 CTS CLEAR TO SEND RS232 INPUT 6 RS232 TXD TRANSMIT DATA RS232 OUTPUT 7 RS232 RTS REQUEST TO SEND RS232 OUTPUT 8 RS232 RXD RECEIVE DATA RS232 INPUT 9 RS232 DTR DATA TERMINAL READY RS232 OUTPUT 10 RS232 DSR DATA SET READY RS232 INPUT 11 RED MODE RED LED SERIAL MODE CMOS IN OUT 12 SWITCH 0 FUNCTION SWITCH CMOS INPUT 13 GREEN SWITCH 1 GREEN LED RESTORE CMOS IN OUT 14 BLUE BLUE LED CMOS OUTPUT 15 UART CTS CLEAR TO SEND CMOS INPUT 16 UART TXD TRANSMIT DATA CMOS OUTPUT 17 UART RTS REQUEST TO SEND CMOS OUTPUT 18 UART RXD RECEIVE DATA CMOS INPUT 19 UART DTR DATA TERMINAL READY CMOS OUTPUT 20 UART DSR DATA SET READY CMOS INPUT J3 Pin Number 19 RESET HARDWARE RESET CMOS INPUT Table 8 Bluetooth module pin out Please refer to ConnectBlue OEM Serial Port Adapter Electrical amp Mechanical Datasheet ref 15 for complete hardware description An OEM Adapter ref Figure 8 allows configuring the OEMSPA13i Bluetooth module This board is actually a mother board including a DB9 RS232 connector an external power supply a RGB led on
20. 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 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 de vice 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 ar
21. CB BOTTOM SIDE Annex 3 Figure 4 insulator plates Annex 3 Figure 5 the whole device opened INRIA 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 2 2 0 Flash Toolkit Renesas FDT 2 2 0 GNU H8 C KPIT wingnuh8v0303coff 0 BlueTooth Module ConnectBlue OEMSPA131 Eurodis ref 158 web21 Software ECI API ConnectBlue CB BTEDKO0I Eurodis 305 Sensor MEMSIC mxr2999m Eurodis 20 Sensor PCB MEMSIC MXEB 002 L Eurodis Interface module PCB INRIA Inria ws Teleph Inria ws 7 Static relay CLARE LBA110 Radiospares 8 Logic And Texas Instru 745 A HCTOS8 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 senso
22. IE m cp er NOLING HSNd 091 v C o Oo 2 ET X cy Ovid G37 Bougy 6 MSI o 0000 snuva 275 fe def suondo sauossant 4 139Yd 1211 3 35 34n3de5 A X RT N 0289 46 7 2 Interface Module PCB component and net lists Herv Mathieu Component Name Abbreviation 1 2 PUSH BUTTON PB 3 LBA110 LBA 4 R4 R4 5 R3 R3 6 LED_R LR 7 R2_ R R2R 8 LED_G LG 9 R2_G R2G 10 LED_B LB 11 R2 B R2B 12 LED DIAG LD 13 RI RI 14 SENSOR 5 15 BLUETOOTH BT 16 74 08 17 MC CNI CNI 18 MC CN2 CN2 19 ANALOG CONNECTOR ANA 20 JUMPER JP 21 CONNECTOR IO Table component list INRIA Wireless Sensor Based on Bluetooth Technology 47 Net Connections 1 GND BAT 1 LBA 4 LD 2 S 1 BTC HCT 7 CN1 1 2 25 26 CN2 1 2 26 JP 2 IOC 2 VCC SVolts R3 1 5 2 2 14 CN1 23 10 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
23. ISSN 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 INRIA RH NE 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 We investigated also off the shelf commercial wireless sensors This class of informa
24. Rh ne Alpes Experiment laboratory we will justify why wireless sen sors are so interesting and why it makes sense designing a home made wireless sensor For that we will explain first what target applications are and then we will report investigation done on existing related research programs and off the shelf products At the end we will propose a general architecture for wireless sensor and give off the shelf electronic module candidates 2 2 INRIA Rh ne Alpes experiment lab The INRIA Rh ne Alpes experiment lab ref web00 is working on robotic systems like biped robot or dedi cated medical robotic devices The team 10 persons is composed of technicians and engineers with mechanical electronics and software skills They are working together with researchers on experiments They provide high quality robotic systems One of the major designs is a biped robot which is discussed below 2 3 Target applications 2 3 1 Biped Robot The biped robot is a 15 dof degrees of freedom robotic system ref 1 This biped robot has been built by the Laboratoire de M canique des Solides de l Universit de Poitiers mechanical skill the service robotique de l INRIA Rh ne Alpes electronics skill and the research group BIP of INRIA Rh ne Alpes control law part Several sensor devices are plugged onto the biped robot for delivering information to the controller Force sen sor devices are located under feet potentiometers are fixed on
25. able services First profiles defined are GAP 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 10 GOEP generic object exchange profile 11 OPP object push profile 12 FTP file transfer profile 13 SP synchronization profile 9o UY RT N 0289 18 Herv Mathieu Off the shelf modules are usually delivered with a partial stack up to HCI Three solutions are on the market for completing the Bluetooth stack e Some companies for instance Widcomm ref web26 have written a certified Bluetooth stack You get the whole source code for a big amount of money One or two compiled profiles can be delivered for less money e Download a free but not certified Bluetooth stack OpenBT ref web25 and Bluez ref web24 are based on the Linux distribution e Write your own Bluetooth stack upon the HCI which means a six months software project Due to the Bluetooth chips limitation too many profiles loaded on module reduce dramatically RF performance A second host for instance a micro controller usually runs part of the protocol We looked for purchasing a module operating a profile like the serial port or the LAN profile This kind of module is not so common it is expensive too But it can reduce dramat
26. age element is 3 6 Volts Cell power is be tween 400 milli Amperes per hour and 1500 milli Amperes per hour for AA battery type The typical discharge current value is between 1 milli Ampere and 400 milli Amperes The charge strategy is to provide a constant voltage 4 2 Volts The charge process ends when the load current reaches zero Li ion battery is intensively used for video recorder laptop and digital camera It becomes also a growing market for Radio Control Mod eler and embedded systems in general A drawback of this technology is its relative weakness Charging a Li ion cell over 4 2 Volts or discharging a Li ion cell when voltage is under 2 7 Volts will definitively damage your cell Most of Li ion batteries are pack aged in a hermetic box containing a safety electronic circuitry This circuitry plays as a safety switch to prevent damaging the cell We did not find any off the shelf Li ion cells in a raw format NiMH Nickel Metal Hybrid battery is more affordable than Li ion battery The technology is less efficient in terms of power versus weight but is more suitable for high current load NiMH element voltage is 1 2 Volts AAA or AA cylindrical format is the common packaging format The document ref 10 gives an interesting overview of battery technology The following websites ref web34 web35 web36 and web37 describe existing products INRIA Wireless Sensor Based on Bluetooth Technology 19 We consider us
27. al 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 in network and communication research programs OEM products usu ally are based on non Bluetooth technology Research groups working on this product class claim that the Blue tooth protocol is too complex and too slow during the connecting process Therefore they choose RF technolo gies 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 makes sense to design a home made wireless sensor
28. an 60mm x 60mm General requirements for micro controller module are summarized here e Small footprint less than 50mm x 50mm e Power consumption less than 120 milli Amperes UART any micro controller get at least one This port is connected to Bluetooth module e Atleast 4 AD inputs for instance for two dual axis inclinometer sensors At least 10 bits precision is required This means 360 1024 equal 0 35 degree angle resolution for a 360 degrees sensor analog sig nal Over 4 digital inputs Over 4 digital outputs Flash memory Intelligent power management capability for reducing power consumption Single power supply either 3 or 5 Volts but 3 Volts would be better C language development tool available INRIA Wireless Sensor Based on Bluetooth Technology 15 2 7 2 Examples 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 10 Software Dev Cost controller mm Tool eu ros 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 compiler 165 ref web07 ST10F168 typ www keil com RENESAS M
29. are reported in Experiments and results section Power saved mode micro controller side The goal of this program part is switching the micro controller module to a power saved mode in order to reduce the power consumption The strategy is as follows INRIA Wireless Sensor Based on Bluetooth Technology 35 Anew 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 micro controller goes to standby mode when the function sleep is called It wakes up for different reasons One of them is an incoming interrupt interrupt handler attached to an IRQO input pin sets 1 or resets 0 a flip flop semaphore depend ing 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 followings actions happen within a session 1 At power on the micro controller does its initialization then calls the sleep function and en te
30. cols vertical slices ref Figure 2 13 different protocols have been defined during the very first specification More profiles have been added during last years INRIA Wireless Sensor Based on Bluetooth Technology 17 vCard vCal RFCOMM Figure 2 Bluetooth specification protocol stack 1 Radio The Radio layer defines the requirements for a Bluetooth transceiver operating in the 2 4 GHz ISM band 2 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 3 LMP The Link Manager Protocol LMP is used by the Link Managers on either side for link set up and control 4 HCI 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 5 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 6 RFCOMM The RFCOMM protocol provides emulation of serial ports over the L2CAP protocol The protocol is based on the ETSI standard TS 07 10 7 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 avail
31. cro 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 Capteur sans fil bas sur la technologie Bluetooth Herv MATHIEU herve mathieu inrialpes fr Th me 3 interaction homme machine images donn es connaissances Rapport technique n 0289 D cembre 2003 56 pages R sum Ce document d crit un projet men au sein du laboratoire d exp rimentation de l INRIA Rh ne Alpes Le but de ce projet est de maitriser la technologie sans fil dans le cadre de capteur pour la robotique dont la ro botique m dicale Ce projet peut tre scind en deux phases qui sont report es dans le document sous deux parties diff rentes Overview et proof of concept prototype La premi re partie concerne l tat de l art les technologies mises en oeuvre et l architecture g n rale On y re trouve e une liste des projets de recherche travaillant sur ce type d application des produits industriels utilisant les m mes technologies e des modules candidats pour r aliser notre prototype Cette partie d crit aussi ce qu un prototype pourrait valider en terme de technologie et de fonctionnalit s La seconde partie d crit comment un prototype con u sur les bases nonc es dans la premi re partie a t r ali s avec succ s Elle est organis e comme suit e sp cification compl te mat rielle
32. d connectors Connecting device is not so reliable and is expensive too Everyone with some practical experience on hardware design knows that many hardware dysfunctions are due to connection problems Connecting grounds is another challenge when integrating electronic modules together A bad strategy for con necting different grounds may induce current loops risk And when it occurs system might be damaged and it is always very difficult to fix it Wireless sensor is a good alternative to this problem And what about inserting a centimeter scale sensor into a human body It is obvious that a wireless solution is better than a wired solution On the other hand many technology gaps have been bridged during last years Radio Frequency devices are now ready for industry wide bandwidth high reliability and low power consumption Cell phone application is a perfect example e Size and power consumption of sensors are dropping down dramatically thanks to MEMS and other CMOS integrated chip technologies e Micro controllers are powerful enough for most applications Power consumption is low Integrated functions like analog to digital converter ADC digital input output or TIMER are easy to implement Because it seems that wireless sensor technology could improve many robotic and medical applications we decided to launch a six month project ref annex 5 aiming at mastering this technology After a short presentation of the INRIA
33. dapting 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 Merle tee GND l BLUETOOTH GREEN LED 13 a MODULE vec a R 20 chins RXD S5 TXD MISE LLL oe CN220 MICRO 10 007 OOND CN2 9 CONTROLLER SENSOR POWER SUPPLY MODULE 9 YOUT TER CN2 10 2 23 POWER CONTROL yee 1 1 l PUSH BUTTON i 1 VCC RA 1 1 R3 GND i LED 2 1 1 15 ner Ses Sin 1 a 7 sr LBALIG 1 i Rl kaolhuns 1 R2 lkolhuns 1 R3 480 chins l 1 1 ENERGY WIRELESS SENSOR TESTBED Figure 10 schematic layout RT N 0289 32 Herv Mathieu The following figure ref Figure 11 represents the interface module PCB top view Remarks about the PCB LED DIAG diagnostic led PUSH BUTTON and Sensor device are fixed to front end of containing box B
34. dle 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 coor dinate 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 robot orientation too Both information coherencies can be checked thus avoiding ha
35. e also materialized with a electronic module RT N 0289 12 Herv Mathieu WIRELESS MODULE SERLAL LINK ANALOG MICRO CONTROLLER SENSOR o MODULE d MODULE DISPLAY DEBUG VO POWER CONTROL POWER SUPPLY Wireless sensor architecture Figure 1 wireless sensor general architecture Let s see in details each part Sensor MEMS sensors are everywhere today Magnetic temperature humidity vibration position you can measure what you need for few square millimeters and little energy Micro controller tens of micro controller cards are found on the market What we need is a low power micro controller with few analog to digital converters ADC Because some calculation may be done on the micro controller for instance for data conversion it is worth to skip 8 bits micro controllers and to focus 16 or 32 bits versions Products like Microchip family or Infineon C16x fam Hitachi H8 family or Texas Instrument MSP430 are fitting Wireless communication Any Bluetooth module on the market has almost all the same hardware de sign Some modules are built with antenna some without Module control is done with a serial or USB Universal Serial Bus communication link The main difference resides in software layers The Blue tooth software stack is complex Modules usually do not implement the whole protocol but all of them implement Bluetooth stack
36. e arc e Bandwidth better than 100 Hertz e Distance between PC and device up to 10 meters Bluetooth class IT Software development C language e Micro controller is ready for working Source codes are available Renesas software development tool kit 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 Sterilizable package 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 A 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
37. e clearly identified thus making the integration process 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 euros 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
38. ears on the second HyperTerminal window Then we select the second HyperTerminal window Any character typed appears on the first Hyper Terminal window We get a transparent RS232 channel over a Bluetooth link Bluetooth H8 3664F MEMSIC first test program using complete hardware configuration We use the program written for Timer amp Analog reading case MEMSIC the micro controller and the Blue tooth module are connected via a home made interface module On the other hand we run a HyperTerminal on the PC connected over COMS Bluetooth dongle Program runs successfully For the very first time we are able to measure the whole module power consumption The measurements are reported in the Experiments and results section Bluetooth H8 3664F MEMSIC Console program access time measurement We use the program written for Timer amp Analog reading case MEMSIC the micro controller and the Blue tooth module are connected via the home made interface module On the other hand we run a Console program developed with Visual C Program sequence is 1 opening a COMS communication channel then 2 re questing a hundred analog scans while measuring the elapsed time then 3 closing the communication link then 4 displaying on screen the elapsed time total and average measured In fact there are two methods for requesting analog scans The first method consists on doing a loop which does a bunch of analog scan requests
39. ectors ref Table 7 CNI Name 3664 pin out CN2 Name 3664 pin out 1 VSS 9 1 VSS 9 2 VSS 9 2 VSS 9 3 PB4 AN4 55 3 P56 SDA 26 4 PBS ANS 56 4 P57 SCL 27 5 PB6 AN6 57 5 P7A TMRIV 28 6 PB7 AN7 58 6 P75 TMCIV 29 7 PB3 AN3 59 7 P76 TMOV 30 8 PB2 AN2 60 8 NMI JP3 35 9 PBI ANI 61 9 P80 FTCI 36 10 PBO ANO 62 10 P81 FTIOA 37 11 VCI 6 11 P82 FTIOB 38 12 RESET 7 12 P83 FTIOC 39 13 TEST 8 13 P84 FTIOD 40 14 P50 WKPO 13 14 P85 JP2 41 15 P51 WKPI 14 15 P86 42 16 P52 WKP2 19 16 87 43 17 P53 WKP3 20 17 P20 SCK3 44 18 P54 WKP4 21 18 P21 RXD uart 45 19 P55 WKPS ADTRG 22 19 P22 TXD uart 46 20 P10 23 20 P14 10Q0 51 21 11 24 21 15 1 52 22 12 25 22 16 2 53 23 VCC 5 Volts 12 23 P1710Q3 TRGV 54 24 PS IN 24 RXD RS232 25 VSS 9 25 TXD RS232 26 VSS 9 26 VSS 9 Table 7 AE 3664FP module pin out INRIA 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 debug ging 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 D
40. er inclination ADXL202 40 ANALOG DEVICE ref web04 Angular rate sensor gyroscope ADXRS150 40 VECTOR TECHNOLOGY Laser diode 5001 21 130 CEA LETI ref web05 8 and 9 3Accelerometer 3magnetometer Prototype Table 1 sensors 2 6 4 To be demonstrated with a prototype e In one hand the sensor must be properly powered It must be far away from electronic noise sources On the other hand we have a wireless module Its power consumption is much higher when communi cation takes place Therefore it can create power supply noise A prototype will validate that a sensor is working well in this context e How the sensor module should be installed into the wireless sensor box For instance an inclination sensor must be positioning with accuracy Registration between the sensor and the box should certainly be done Shall we use mechanical references or an experimental calibration phase 2 7 Micro controller module 2 7 1 Specification Tens of micro controllers exist They are based on 8 16 or 32 bits core Implementing a micro controller in a design implies developing an electronic PCB with some circuitry quartz resistor and capacitor Because we wanted to minimize PCB developments we look for an off the shelf mod ule The goal was to have rail to rail connections when possible In fact we found very few modules according to the specifications Modules listed after include modules with dimensions over 50mm x 50mm but less th
41. er H8 3664F Hardware The Renesas formerly Hitachi H8 3664F is a 16 bits micro controller The table ref Table 6 and the figure ref Figure 5 give the device overview INRIA Wireless Sensor Based on Bluetooth Technology 25 e 5 operation 2x 8 bit timer e 16MHz H8 300H 16 bit CPU core e ix watchdog timer 32 kHz sub system oscillator e xUSART e Wide range of low power operating modes e 1 e 8 32kBytes ROM 512 IkBytes SRAM 8 channels 10 bit A D 32kBytes single supply Flash 2kByte SRAM e 371 0 pins 8 x 20mA ports Flash version only e 11 External Interrupts e Ix 16 bit timer with 4 capture compare e On chip debug port Table 6 H8 3664F main features m E 3288 PIOTMOW 2 i Pit 3 P12 14 00 PISARQI PIGIRQ 7 P2OISCKS P21RXD P22 TXD PTE TMOV P75 TMCIV P74 TMRIV 2 P84 FTIO0 85 P57 SCL Pesrrrioc 85 PS6 SDA PATIOS 85 PSSIWKPSYADTRG PBI FTIOA 2 PSA WKPS POOFTC JG 8 PS2 WKP2 P51 WKPI PSO WKPO 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 26 Herv Mathieu Figure 6 AE 3664FP module H8 tiny I O board TERA2 is a development board for programming AE 3664FP module The AE 3664FP IO signals are reported to two CN1 amp CN2 26 pins dual 2 54 millimeters pitch conn
42. er TRUE or FALSE The first process is a watchdog function activated every xx minutes for instance 10 minutes The function core does a test on semaphore If the semaphore is TRUE then a digital output state is changed thus cutting power supply else the semaphore is changed to TRUE state The second process consists on changing the semaphore to FALSE when an incoming command occurs There fore module will switch off 10 minutes after last command occurs 3 4 4 Battery specification The prototype is energized by a primary battery A PP3 rectangular format is used because of the following features e tis commonly used format voltage is 9 Volts It is compliant with 7 12 Volts range for the regulator located on the micro con troller module e compactness 25mm x 17mm x 46mm is better than the AA or AAA cylindrical formats espe cially for a cubic box container 3 5 Interface module 3 5 1 Why do we need a home made interface module In fact it is obvious that connecting modules coming from different module makers requires an interface mod ule The reasons are as follows Due to incompatible electric signals rail to rail connections can not always be achieved For instance 3 3 Volts CMOS Bluetooth output should not be directly connected to a 5 Volts CMOS H8 3664 input In this case circuitry must be added off the shelf modules do not have same dimensions and input output connectors do n
43. et logicielle du prototype e les outils utilis s durant cette phase e les r sultats obtenus Un effort tout particulier a t fait pour que ce prototype puisse devenir moindre co t un outil utilisable dans des applications robotiques r elles Mots cl s capteur MEMS sans fil Bluetooth micro contr leur INRIA 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 6 Herv Mathieu 1 Contents Wireless Sensor Based on Bluetooth Technology 1 1 Contents mr ue coiere re i nn re nr tee tg etae ae de RE 6 2 Part Omer Overview iacta dette ee elsi tie ie eee tte ee Ee 8 2 1 Inttoduction e D RO rn t ERE Trees 8 2 2 INRIA Rh ne Alpes experiment 1ab nennen nennen enne nennen 8 2 3 Et ae ie e dede 8 22221 jBiped RObot iir et er backs sa E este utres tete e v YES Eee ERAS 8 2 3 2 Medical applications naines side 9 2 4 Existing SiMla pro ects o etel Mn D 10 24 4 Research projects ios octo eet e D as ee a ae nee 10 2 42 Commercial
44. ete software development tool kit was validated compiler linker flash toolkit On the PC side we use a HyperTerminal application We validate 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 34 Herv Mathieu We test here the Bluetooth module The module is configured using the mother board and the wizard Microsoft Windows program described above After the configuration ends we run a HyperTerminal program for connect ing the module over the COMI channel On the second hand we use a Bluetooth dongle connected on the same PC over an USB port We use a wizard application delivered with dongle for discovering Bluetooth entities present in the vicinity Hopefully the mod ule is recognized The wizard allows pairing a virtual port COMS in our case with the entity discovered A second HyperTerminal is opened over COMS First we select the first HyperTerminal window Any character typed in it app
45. evelopment Toolkit FDT 2 2 is used for flashing programs on the micro controller HEW GUI allows 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 0701 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 0dBm 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 UART 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 OEMSPA
46. f Figure 12 Note the battery consists on metallic material which could affect the radio frequency RF transmission There fore the Bluetooth module antenna is located at the opposite side from the battery thus limiting RF problems INRIA Wireless Sensor Based on Bluetooth Technology 33 TOP VIEW fwithout cover LEFT SIDE VIEW 35 A m o tA m n MICRO CONTROLLER T MICRO CONTROLLER a INTERFACE MODULE INTERFACE MODULE BLUETOOTH BLUETOOTH Y Figure 12 module packaging The modules mounting instructions are given in the document annex ref 3 The sterilization process 1s 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 prototype 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 resource The compl
47. h is working on a Bluetooth based wireless sensor implementing TinyOS ref web32 The original smart durst goal 1s building a 2mm x 2mm x 2mm cube including power supply based on solar en ergy RF communication and or Laser based communication and sensor devices Technology is based on MEMS For now they developed centimeter scale wireless sensor Smart Its ref web27 This 1s collaboration between Lancaster University ETH Zurich University of Karlsruhe Interactive Institute and VTT Technical Research Centre of Finland The project goal is to develop unobtrusive deeply interconnected smart devices called Smart Its that can be attached to everyday appliances in order to support new functionality novel interaction patterns and intelligent collaborative behavior Smart Its will be cheap Each of the labs involved in this project has developed its own prototype ETH has the most documented proto type ref 2 and 3 Another project is the MIT Ultra Low Power Wireless Sensor Project ref web33 under the direction of Professor Charles Sodini The project is funded over the next four years by the Advanced Research Projects Agency ARPA 2 4 2 Commercial products Crossbow ref web12 is a USA company delivering products developed at University of California at Berke ley Products base name is MICA OEM products are available Crossbow ships three Mote Processor Radio module families MICA MPR300 2
48. ically the development cycle We consider in a future project working with a basic module Therefore it could reduce the module cost and we could purchase any commercial module The drawback is that the Bluetooth protocol stack will end at the HCI protocol stack Missing Bluetooth stacks will have to be developed 2 8 5 Tobedemonstrated with a prototype e How complex is a development using a Bluetooth module In one hand very few experiences have been reported using Bluetooth within research project ref 2 3 and 7 On the other hand Blue tooth companies announce day to day new modules available e The power consumption and the power management are not clearly described in technical documents Some reports concerning research project rise up problems concerning the power consumption e Does it works within a robotic environment Bluetooth primary market includes cell phone computers PDA Robotic or medical environments include a lot of metallic parts noisy machine like X Ray scan ner 2 0 Energy 2 9 4 Technologies Technologies used in such systems are usually based on solar power or battery power We do not here address self powered technology based on RF transmission Solar power is a valuable choice for outdoor experiments and the described applications sets typically indoor Thus we give up with solar power At the end we looked for battery technology The Li ion battery technology is today the most efficient Li ion volt
49. ing 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 15 low Then the strategy is different according to the battery technology Li ion battery output voltage is almost linear with respect to discharge 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 non 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 shall consider the ca
50. ion XOUT and YOUT are acceleration ratio metric outputs The related formulas are the following XOUT gravity sin ANGLE X and YOUT gravity SIn ANGLE Y The formula calculation is performed on the Host PC side On the wireless sensor module side two offsets are applied on analog scan values These offsets represent angle offsets X and Y direction between the sensor itself and the box container The offsets calculation protocol is as follows 1 The offsets are set to zero 2 The wireless sensor device relays on a horizontal table An analog scan 1s performed 3 The analog scan results are written in the embedded code as desired offsets In fact we suppose that X and Y directions are parallel with the box main directions This is achieved by gluing sensor card below top panel box with accuracy This method is consistent with sensor precision which is more or less 0 5 degree arc For higher precision another registration process must be done We have to know how values obtain in the sen sor coordinate system can be represented in the box coordinate system This is achieved by finding a 2x2 matrix The registration protocol could be as follows 1 we dump X and Y sensors outputs when moving the box around the box X axis then 2 we dump X and Y sensors outputs when moving box around the box Y axis then 3 we calculate by a mean square algorithm the sensor axes represented in the box coordinate system 3 3 2 Micro controll
51. is 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 depending 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 pre cision 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 eleme
52. log 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 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 cutting the power supply Remark The power supply will be turned off even if a client is connected Criteria used deals only with incom ing commands 3 3 Off 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 MXR2999 design is ba
53. logies Conseils R alisatons Club de robotique de l E S E O Olivier Cochelin Emilie Sosna 2002 11 MXR2999GL ML datasheet MEMSIC 2003 12 Evaluation Board MXEB 2 MEMSIC 2003 13 AN 00MX 007 Application Note Rev 05 02 Inclination Sensing with Thermal Accelerometers MEMSIC 2003 14 Hitachi Single Chip Microcomputer H8 3664F Hardware Manual Renesas 2002 15 OEM Serial Port Adapter 274 Generation Electrical amp Mechanical Datasheet ConnectBlue INRIA Wireless Sensor Based on Bluetooth Technology 2003 e 16 Serial Port Adapter 2 Generation User Manual 1 3 ConnectBlue 2003 e 17 Serial Port Adapter 2 Generation AT Commands ConnectBlue 2003 RT N 0289 43 44 Herv Mathieu 6 Related web sites web00 http www inrialpes fr sed web01 http www robodoc com web02 http ndigital com 6 1 Sensor providers web03 http www memsic com web04 http www analogdevice com web05 http www leti cea fr web06 http www memsnet org 6 2 Micro controller module providers web07 http www phytecfrance com e web08 http www microtronique com e web09 http www eu renesas com 6 3 Wireless sensor providers including Bluetooth amp other RF technologies web10 http www oceanasensor com web11 http www sensicast com web12 http www xbow com Products Wireless Sensor Networks htm web13 http www millenial net 6 4 Bluetooth chip or module providers web14 htt
54. luetooth module is located behind the interface board and is screwed on the interface board using two through holes 35 56 mm 14 x 2 54 O v 40 8 o 3 0 O O o olo o o 05 0 Gag 16 olo o 2 lo G7 dem eee z oloo o o f _ ES oloo of olo SO o op o o gap 4 0 o ee MIMETTL TR 2 Figure 11 PCB layout The full module schematic is given in the document annex ref annex 1 and the net list is reported in the document annex ref annex 2 3 6 Container amp Packaging We purchase a 55mm x 55mm x 42mm box made in ABS plastic A rectangular 50mm x 36mm plate is inserted between the battery and the electronics parts as insulator mate rial Two through holes are machined on the top panel box One is a 2 millimeters diameter for diagnostic LED The other one is a 7 5 millimeters diameter for the push button Both components are glued The sensor module is glued on back side of the top panel box The other modules take place as shown in next figure re
55. n g Because the sensor is used as an inclina tion sensor only one g is measured therefore output signal is between 1 Volt and 1 Volt 2 Volts range for a range of 90 90 degrees arc On the micro controller side the analog inputs range is 10 bits for a 0 5 Volts input signal As conclusion the measurement resolution is 0 44 degrees arc 180 deg divided by 2 5 range of 1024 points The sensor resolution is better than 1 milli G as announced in the sensor datasheet Therefore a better analog converter would increase the final accuracy This analog converter could be interfaced with the micro controller using the I2C channel link Concerning the micro controller module the limitations are as follows e The H8 3664F implements only one UART This UART is connected to the Bluetooth module A sec ond UART would have been great for connecting another device During the development phase the micro controller module was move back and forth between the development board and the interface board A second UART would have made it easier The second limitation coming from the UART is due to a lack of flow control Only TXD and RXD signals exist on the micro controller side The Bluetooth module provides all necessary signals for flow control but it can not be used here Therefore the embedded program never knows if the Bluetooth module receives all the characters sent Fortunately the Bluetooth module implements a 128 bytes FIFO Fi
56. nts 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 RT N 0289 14 Herv Mathieu Powering a low power laser beam is an example This kind of device is controlled by a simple digital output This makes it easy to integrate A more ambitious goal could be controlling a motor In this case a power stage has to be added The micro con troller resources must be consistent that means for instance the capability for reading encoders The communi cation bandwidth detailed above would be enough Providing the embedded energy is another big issue 2 6 3 Examples We listed in table ref Table 1 sensors that could be used Trademarks Type Reference Cost euro MEMSIC ref web03 Accelerometer inclination MXR2999 30 ANALOG DEVICE ref web04 Acceleromet
57. odule 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 The 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 what kind of Bluetooth function alities we need A full control of the Bluetooth stack means hundreds of code lines But a minimum configuration 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 1 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 10 meters for 1 milli Watt version low cost up to 8 connected nodes together piconet It fits projects
58. ommunication channel 3 Wait for an answer 4 Split incoming message and fill a semantic structure containing the returned command the module status and eventually the returned value s fields Analyze the common fields Analyze the fields depending on the command sent 7 Back to state 1 Stream mode is an exception for the above state machine Messages due to stream mode incoming messages with no associated commands are treated within state 6 Analyze fields depending on command sent In details when a stream start command is sent the associated answer is received then a predefined number of stream messages are received then a stream stop command is sent automatically It supposed that no commands are sent within this program phase A more elaborate protocol including multi threaded processes would allow managing the whole protocol in cluding stream mode in a more efficient way 3 9 Experiments and Results The following picture ref Figure 13 shows how experiments take place A power supply replaces the battery for the development phase Current measurements are done on it Voltages are measured with a multimeter A breadboard provides a smart tool for testing new hardware component The prototype parts relay on the table The PC and the Bluetooth dongle are not represented INRIA Wireless Sensor Based on Bluetooth Technology 37 The first objective was to contain the whole
59. ot have the same shape So modules can not be stack up directly e Some features not supported on the modules can be added Using LEDs for visualizing the Bluetooth module state is an example e From the mechanical point of view an interface module provides a reference for fixing other modules thus avoiding moving parts inside the container At the end the interface module implements the following features A mechanical interface for screwing Bluetooth module two 2 5 millimeters diameter through holes INRIA Wireless Sensor Based on Bluetooth Technology 31 3 5 2 A 7x1 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 static relay A connector for the dual axis sensor Power Ground 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 74 08 4 AND logic chip for a
60. oth chipset exist Ericsson Infineon ref web17 CSR ref web14 Philips ST ref web19 but a large number of modules are on the market Common features are e Inputs control modes available are USB UART and PCM for voice transmission A chipset with flash memory e Anantenna which may be an option for enabling more powerful antenna The module power consumption is between 50 and 80 milli Amperes when transmitting less during other modes The power supply voltage is usually 3 Volts Some existing Bluetooth modules are listed in next table ref table 3 Common features of the listed modules are 1 French distributor available 2 class II Bluetooth 3 on module antenna 4 GAP amp SPP profiles and 5 UART port control Company Product name Size mm Misc Power supply Cost euros ConnectBlue OEM Serial 23x36x5 Multi connec 3 6 Volts 40 158 ref web20 Port Adapter tions mA SV max 13i Mitsumi WML CL10 12x18x2 Point to point 1 8 amp 3 3 Volts 240 ref web22 only 60mA Table 3 Bluetooth modules Euridis ref web21 is a French distributor for ConnectBlue products Micropuissance ref web23 is a French distributor for Mitsumi products 2 8 4 Bluetooth specification protocol stack The Bluetooth specification deals with hardware and software The software specification is quite complex It includes several stacks horizontal slices and deals with several proto
61. p www csr com web15 http www btdesigner com web16 http www codebluecommunications com web17 http www infineon com web18 http www brightcom com web19 http eu st com bluetooth web20 http www connectblue se web21 http www euridis com web22 http www mitsumi components com Catalog index e html web23 http www micropuissance fr 6 5 Bluetooth stack providers e web24 http bluez sourceforge net e web25 http sourceforge net projects openbt web26 http www widcomm com 6 6 Other Bluetooth related companies web27 http www smart its org web28 http www bluetooth com web29 http www nohau co uk web30 http www palowireless com 6 7 Other RF solutions e web31 http robotics eecs berkeley edu pister SmartDust e web32 http webs cs berkeley edu tos e web33 http www mtl mit edu jimg project top html 6 8 Battery related web sites web34 http www bktsi com powerflite powerflite htm web35 http industrial panasonic com ww products e battery e battery e html web36 http www sanyo energy europe com web37 http www buchmann ca faq asp INRIA 45 7 Annexes Wireless Sensor Based on Bluetooth Technology 7 1 Interface module schematic Y 09I A OO OT X 0 papajas sway oj ELEI 002 v0 JequaAoN Aepsan ama 931 jueunaog DSUS NK Nx N3349 AMAL
62. pability 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 autono mous 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 Tobedemonstrated with a prototype exhaustive 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 e 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 process In o
63. r standby mode 2 When aclient 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 Timer interrupt handler it manages local time watchdog and synchronous analog scans requests External interrupt handler 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 incom ing 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
64. r and the Bluetooth module have such a power saved mode The strategy for getting this mode is presented in the software section The sensor module does not have any power saved mode but the power consumption is low less than 4 milli Amperes RT N 0289 30 Herv Mathieu The power consumption results are reported in Experiments amp Results section Anyway the minimum current consumption 1s obtained when both micro controller and Bluetooth module are in power saved mode The result value is 18 milli Amperes Considering a 700 milli Amperes hour battery a power supply failure could occur after about 36 hours Of course it is reduced when using the device in transmitting mode for a while This is clearly a limitation for using the wireless sensor 3 4 3 Auto power off We decide to implement an ultimate power management procedure the power off sensor feature This is a two steps procedure First of all a push button is added for powering on module Then a software watchdog implements an auto power off mode The final sensor device behavior is as follows A push button pushed then released phase is the only way to switch on sensor device e The micro controller switch off sensor module when not used for a while software command generated by host allows switching off module From the software point of view two asynchronous processes take place and one semaphore memory cell is used Semaphore cell is eith
65. r 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 52 7 5 Project milestones Herv Mathieu Date Action done March 2003 Idea that technologies are ready for efficient wireless sensor devices April may 2003 Investigate technologies using World Wide Web existing wireless sensors research projects May 2003 Choose the Bluetooth technology for wireless communication May 2003 Choose a dual axis inclination sensor as a test bed sensor May 2003 Investigate battery power supply technologies Li ion Nimh June 2003 First document draft Wireless Sensor Module Based on Bluetooth technology over view June 2003 Choose the micro controller H8 3664F July 2003 Choose the Bluetooth module ConnectBlue OEMSPA131 July 2003 Buy the micro controller module and the Bluetooth module August 2003 First programs on the micro controller no sensor no Bluetooth module September 2003 Run a program on the micro controller using the dual axis inclination sensor September 2003 Test bed interface module first design September 2003 Run a program on the micro controller using the Bluetooth module The Bluetooth module configuration is made by a Windows wizard amp AT commands September 2003 Power saved mode on the micro controller and
66. rst In First Out memory for the incoming RS232 characters e The ADC isa 10 bits converter The accuracy may be an issue for other sensor devices than the MEM SIC dual axis inclination sensor we tested Other sensor dynamic range may exceed 10 bits e Another limitation of the ADC concerns the input impedance that is required The input impedance must be less than 5 kilo Ohms In other terms the sensor device must provide more than 1 milli Ampere for a 5 Volts supply MEMS sensor are designed for low power applications This can be a limitation for connecting rail to rail sensor devices An operational amplifier might be used to over come this problem The MEMSIC sink current is 0 1 milli Ampere which should not be enough Nevertheless we did not notice any problem during tests The main Bluetooth module limitation is the transmission delay Experiments show a 13 milli seconds delay when transmitting over the Bluetooth channel INRIA 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 ar
67. rt eie ee ee ee OR EN ea de Ee 19 3 Part two proof of concept prototype ss 21 3 1 Introduction is 21 3 2 How does the sensor device work ss 22 3 3 Off the shelf devices description ss 23 3 3 1 Sensor module MEMSIC mxr2999m 23 332 Microcontroller H8 30664E tee rte detre enr 24 3 3 3 Bluetooth module ConnectBlue OEMSPAI31 ie 27 3 4 ENGL ES SRE E ETE 29 3 4 1 Power consumption calculation based on datasheets 29 3 42 Powersaved mode sis nine mutant teo e d EO Re RI dt Rues 29 3430 AUTO DOW OTT te Re Rete Ne A tesi Pd HE 30 34 4 Battery ee eR e He E e dee ee rede 30 3 5 Interface Module Ce e eden 30 3 5 1 Why do we need a home made interface 30 3 52 Interface Modi E design t t e emet ise ede tus 31 3 6 Container amp Packaging en e E PR SE ni near tt ono 32 33 Embedded progra ms 2 eme edet de te eevee Ve EE e RU Re dE ee D 33 3 8 Program running on host ise edades eet erectio pee ehe i 35 3 9 Experiments and Results 3 tienne e ns doeet ts 36 3 10 Prototype limitations ceo RD eate Eten de 39 4 Conclusion ss uere Erde ek Ende
68. s back the result Scans are synchronized using the micro controller timer thus allowing different output frequencies At the same time the micro control ler 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 bod 1 1 r 1 1 foi 5 2 o E 2 A m F tt F 1 AS B E e oN 2 E m 1 rod 1 1 1 1 1 pog Fog TIME delay delay ahalog T MICRO CONTROLLER glhir 2 1 Ej f T i i H 1 1 o I oO 1 1 E 1 E S d m 3 M 1 1 1 1 1 1 1 PC Ix TIME delay delay i ahalog Figure 14 communication protocols top synchronous bottom asynchronous 3 10 Prototype limitations The sensor device main limitation concerns its accuracy RT N 0289 40 Herv Mathieu The sensor sensitivity is 1000 milli Volts per gravity acceleratio
69. sed on heat convection and requires no solid proof mass The MXR2999 provides a ratio metric analog output that is proportional to 50 of the supply voltage at zero g acceleration The typical noise floor is 0 2 mg 4 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 5p sH AR SE Figure 4 002 L Basic Board with MEMSIC IC on the side amp MXR2999GL ML Functional Block Diagram RT N 0289 24 Herv Mathieu Pin Number Pin Name Description 1 VSS ground 2 VCC 5 VOLTS 4mA 3 component VREF OUT 2 5 Volts 3 solder TOUT temperature Analog 0 5 Volts 4 YOUT Analog 0 5 Volts 5 XOUT Analog 0 5 Volts Table 5 MXEB 002 L pin out Please refer to MEMSIC MXR2999GL ML datasheet ref 10 and Evaluation Board MXEB 2 ref 11 for a complete hardware description How to measure the angles We consider here using the sensor as an inclination sensor not an accelerometer sensor Please refer to the application note Inclination Sensing with Thermal Accelerometers ref 13 for a complete descript
70. st to power saved mode and then micro controller switches to power saved mode too Power off state All is off A led located on the top panel of the box indicates the device status as follows LED OFF the device is off LED ON the device is connected LED BLINKING the device is on but not connected After a connection has been established with the wireless sensor device commands are sent using ASCII charac ters format A very simple protocol is implemented 1 2 The host sends a command a character The remote device sends back a character string with an ending delimiter End delimiter consists on ASCII new line 0x0A then ASCII carrier return 0x0D Answer begins with command echoing It may include figures or strings which are delimited with and gt The following table ref Table 4 gives the available commands Answer Meaning v lt i gt lt module id gt lt ok gt n r Return module id name inria ra ws 001 a lt a gt lt a0 gt lt a 1 gt lt a2 gt lt a3 gt lt ok gt n r Analog scan channels 0 1 2 3 value 0 1024 lt A gt lt a4 gt lt a5 gt lt a6 gt lt a7 gt lt ok gt n r Analog scan channels 4 5 6 7 value 0 1024 d lt 1 gt lt 0 gt lt 3 gt lt 0 gt lt gt lt gt Analog scan channels 0 1 2 3 x 100 T lt L gt lt a3 gt lt a7 gt lt a3 gt
71. 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 mod ule 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 Bluetooth dongle connected over an USB port 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 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 RT N 0289 36 Herv Mathieu The second sub program consists on a menu providing functionalities described within the How does the sen sor device work section The program state machine runs as follows 1 Wait for a command a character on standard input 2 Send the character over c
72. ther words we explain why wireless sensors were so interesting Then we listed existing related projects or products We mentioned also that none of existing devices fitted the needs thus justifying making a prototype RT N 0289 20 Herv Mathieu We presented a complete and detailed review of technology candidates and a global architecture In other words we suggested that technologies to build such a device were ready But we also list some device features which have to be demonstrated in a prototype the power management fa cilities the wireless link robustness Building a prototype is an opportunity to makes things clear Next part gives the proof of concept prototype specification and talks about experiments and results performed INRIA Wireless Sensor Based on Bluetooth Technology 21 3 Part two 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 small box sensor in order to evaluate its commu nication 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 First it gives how the sensor device works e Then the off the shelf modules used in test bed are detailed
73. tion is useful to know what is reachable in terms of final products However you do not know how company did it the Commer cial product term implies usually a secret process e 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 performed 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 mi
74. up to HCI Host Controller Interface In this case a additional micro con troller runs Bluetooth stack above the HCI layer But some modules implement a full profile for in stance the Serial Port Protocol profile detailed below This profile emulates a wireless serial commu nication link In fact this 1s exactly what we need for the project INRIA Wireless Sensor Based on Bluetooth Technology 13 e Power supply energy this part really depends on other modules During development phase 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 might 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 1 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 abso lute family sensor It deals with physic laws like gravity field or earth magnetic field This kind of sen sor 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 Th
75. 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 BluetoothTM 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 ensuring 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 RT N 0289 16 Herv Mathieu Note about power classes Each device is classified into 3 power classes Power Class 1 2 amp 3 Power Class 1 is designed for long range 100m devices with a
76. zardous 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 devices These active trackers versus passive trackers improve precision 3 a large area inside sur gery 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 In general adding sensors improves a procedure in terms of safety for the patient and precision for procedure But adding wires is a big issue A surgical room is a confined area All material has to be sterili
77. zed RT N 0289 10 Herv Mathieu Having wireless sensors mean fewer wires around the patient and the physician Therefore it provides a more comfortable and safety working environment But to be accepted within medical procedures wireless sensors must fit following conditions 1 they must be safe for patient 2 they must be packaged as small as possible because of confined area and 3 they must be sterilizable We summarize here common features extracted from applications mentioned above In other terms what do we need A set of sensors between 1 and 5 devices All sensor devices are located within a small area inside a 3 meter diameter sphere Sensor devices must be as small as possible hand size It must be sterilizable 2 4 Existing similar projects 2 4 1 Research projects The research projects Smart Durst and Smart its described below are similar to our project because they study wireless sensor The difference is that these projects focus on large scale wireless sensor devices They deal with logical connection and data flow complexity problems In our project only few sensor devices will be connected Our connection strategy corresponds to a master slave configuration Therefore communication is not a big issue Smart Durst ref web31 This project is located at University of California at Berkeley Crossbow ref web12 is an industrial partner in this project Intel researc

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