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1. LCDClear return 1 JERREFERRRERARE RAEE SES EAL EEE LEER EEAEREREEEE ES EE REE EERE ELAS EE AERE EERE A A AA ACACA E S r SICKInit SICK LMS Initialisation Change to installation mode Default Password SICK_LMS JA 20H Select change operating mode g RRE A EAESS LEREEAESLERSERES EEREERELERE LE EE RSENS PEER SEA EES EERE CERES int SICKInit for i 0 i lt 16 i unsigned char init 16 0x02 0x01 0x0A 0x00 0x20 0x00 0x53 0x49 0x43 0x4B 0x5F 0x4C 0x4D 0x53 Cre_ Create Send SICKCreateCRC amp init 0 14 init 14 unsigned char Cre_ Create Send OxFF init 15 unsigned char Cre_ Create Send gt gt 8 res UARTPutChar 0 init i if res 0 LCDPutString Msg Sent to SICK LCDClear else LCDPutString Msg Send Error return res ERRATA EEE FEET RE EERE AR E a ea EEEREN NANA A ee eR A NR SICKInit2 SICK LMS Command String2 Change baud rate to 19200 Baud A O Ae 1 int SICKInit2 for i 0 i lt 8 i unsigned char init2 8 0x02 0x01 0x02 0x00 0x20 0x41 Crc_Create_Send SICKCreateCRC amp init2 0 6 init2 6 unsigned char Crc_Create_Send amp OxFF init2 7 unsigned char Crc_Create_Send gt gt 8 res UARTPutChar 0 init2 i if res 0 LCDPutString Msg Sent to SICK LCDClear else LCDPutString Msg Send Error D3 return 0 ERR a ies ae CRT TEE Oe Sn tg EE
2. Robosoft Homepage http www robosoft fr Cross GCC Web page http www gnu org software gcc gcc html A1 APPENDIX A INRIA Rhone Alpes 12 M Riess Qualification d un t l m tre balayage laser pour la robotique mobile Int gration et experimentations Study of Functions of a Laser Scanner for Mobile Robots Experiments and Implementations A2 APPENDIX A INRIA Rhone Alpes APPENDIX A pees ARRE Initialisation and reset of LMS Le Select Change of LMS operating mode Request for measured values e A NORO Do cc a ORAR A E Ut irc PE ci ocios SOI C ee AOO EE ceci SA en Request for configured field 0x74 Read LMS configuration Request for measured values in cartesian coordinates Define LMS 2xx xxx06 configuration Table A1 Telegram List for Data Exchange from Host to LMS A3 APPENDIX A INRIA Rhone Alpes A gt gt A Aen re E Ml ioscan a IE vico cacon AM asso Ml 0xB6 Send averaged measured values 0xB7 Send partitioned measured values OxBA Information on LMS type Response to change of LMS variant La Send averaged partitioned measured values Response to field configuration Change active field group a Configuration data for programmed fields Current LMS configuration Response to request for measured values in cartesian coordinates Response to definition of LMS 2xx xx06 configurartion Table A2 Telegram List for Data Exchange from LMS to H
3. void SICKGetMsg UARTGetChar 0 amp msg 0 11 STX UARTGetChar 0 amp msg 1 ADR UARTGetChar 0 amp msg 2 LENL UARTGetChar 0 amp msg 3 LENH LenL LenH Len 0x00 LenL msg 2 LenH msg 3 Len LenL LenH 256 Convert HEX to DEC for i 0 i lt Len 2 i CMD N x Data Status CRCL CRCH UARTGetChar 0 amp msg i 4 CrcL msg Len 5 CrcH msg Len 6 J RR RE EEE ETEEN ASSES AEE REESE EEE CLENA ee ORR PERL PEER Nae Se MAAR ARR eer yeh he eee Y SICKGetData To get the useful scan data values 361 values of PO EE ELAR E ES EEAAARE SESE EG BEEERERERE SS define STX 0x02 int SICKGetData UARTGetChar 0 amp data 0 II STX if data 0 STX LCDPutString GetData Err STX LCDClear UARTClose 0 UARTGetChar 0 amp data 1 ADR UARTGetChar 0 amp data2 LENL UARTGetChar 0 amp data 3 LENH if data 2 0xD6 amp amp data 3 0x02 LCDPutString GetData Err Len LCDClear UARTClose 0 LenL LenH Len 0x00 LenL data 2 LenH data 3 Len LenL LenH 256 UARTGetChar 0 amp data 4 CMD for i 0 i lt Len 1 i UARTGetChar 0 amp datali 5 data UARTGetChar 0 amp data Len 5 UARTGetChar 0 amp data Len 6 CrcL data Len 5 D5 CrcH data Len 6 kkkk k k kK k k k k k k k kK k kK KK kK k k kK kH k k k kK XK K k k kK K KKK k k Kk k k k k k k kK k K K k KKK KKK k kK XK KKK k kK Kk k k k kK K
4. communication controller that implements the CAN controller area network protocol an asynchronous communications protocol used in automotive and industrial control systems It is a high speed 1 Mbit sec short distance priority based protocol that 68 can run over a variety of mediums for exampk fibre optic cable an unshielded pair of twisted pair of wires The TouCAN supports both the standard and extended identifier ID message formats in the CAN protocol specification revision 2 0 part B Each TouCAN module contains 16 message buffers which are used for transmit and receive functions It also contains message filters which are used to qualify the received message IDs when comparing them to the receiving buffer identifiers Photo 1 2 4 1 MPC555 Control Board provided by Robosoft 69 Power supply 18 60V DC from batteries 37 BDM Interface Basic Debug Interface 7 analogue inputs RS 16 logical inputs and 20 logical outputs L Synchronous serial lines SPI Asynchronous serial lines 1 port number 0 Le Asynchronous serial lines 2 port number 1 CAN bus 1 port number 0 LS CAN bus 2 port number 1 4 connectors dedicated to axis control including 1 analogue output per axis Table 1 2 4 1 Description of MPC555 Control Board Photo 1 2 4 1 and Table 1 2 4 1 above describes in detail the MPC555 control board that was used in the project Take note of the designation of the port num
5. 2 3 1 Table 1 2 4 1 Table 1 3 3 1 Table 2 1 2 1 Table 2 2 1 1 Table 2 3 1 1 Table 2 3 1 2 Table 2 3 3 1 Table 2 3 4 1 Table 2 3 4 2 Table 2 3 4 3 Table 2 3 4 4 Table 2 3 6 1 LIST OF TABLES Specifications of Cycab Possible Baud Rate for 40 MHz System Clock Description of MPC555 Control Board Specifications of SICK LMS 291 505 Serial Frame Formats MPC555 UART Interface Functions LMS Telegram Structure Description of LMS Telegram Structure Description of LMS Status Byte Command Telegram sent from MPC555 to LMS Interpretation of Command Telegram Response Telegram sent from LMS to MPC555 Interpretation of Response Telegram Description of Makefile Functions of MPC555 vi 12 14 18 24 25 29 30 32 33 33 34 34 36 Figure 1 1 1 1 Figure 1 1 2 1 Figure 1 3 2 1 Figure 1 3 2 2 Figure 1 3 6 1 Figure 2 1 1 Figure 2 1 1 1 Figure 2 3 6 1 Figure 2 4 1 Figure 2 5 1 1 Figure 2 5 1 2 Figure 2 5 1 3 Figure 2 5 2 1 Figure 2 5 2 2 Figure 3 1 1 1 Figure 3 2 1 1 Figure 3 2 3 1 LIST OF FIGURES Layout of Cycab Network Connections in New Cycab Operating Principle of SICK LMS Scan Angle and Angular Resolution Maximum Configuration for a LMI System Configuration of Required Serial Interface Sub D 9 Pin Connector View Example of Makefile Commands for MPC555 Program Overview of Simulated Environment Request fo
6. SICK LMS in this project It was proposed that the communication with the LMS be made via a real time serial interface using RS422 This MPC555 is programmed to control the SICK LMS and retrieve all scan data values from it Then these data are filtered and only the necessary required values are sent to the Linux PC via the CAN network The Linux PC contains all the high level application control programs like Trajectory Planning and Car Following When the Linux PC receives the filtered data from the MPC555 the programs will process these vital data and generate results based on its control algorithm Then these results are redistributed to the front and back 60 MPC555 for processing Finally these 2 MPC555 will control the motor nodes based on the results The network within the dotted zone shown in Figure 1 1 2 1gives a good illustration of the work scope of this project 61 rsesanssz MPC555 Left Wheel i i Left Wheel sn Back Steering i Front Steering MPC555 MPC555 g BACK FRONT Right Wheel i i Right Wheel Jovstick LINUX PC Figure 1 1 2 1 Network Connections in New Cycab 62 63 1 1 3 Goals of Cycab Researchers at INRIA has been working on this intelligent vehicle project with the following goals in mind 1 1 3 1 Increase Safety of Road Transportation It is well known fact that though road transport brings conveniences to people it is not safe In fact this mode kills hundreds
7. control from the user Works on the Cycab involve implementing numerous safe lane guiding systems speed control and others All these are aimed at improving the safety of road transport and also easing the booming population of private cars in the cities This Industrial Attachment at INRIA Rhone Alpes was made possible because of a collaboration tie between NTU and INRIA During the attachment period of about 6 months a project with the objective of implementing a real time serial interface between SICK LMS and MPC555 microcontroller was given The reason was that a new Cycab equipped with the new generation microcontroller MPC555 is being built and there was a need to interface the SICK LMS and the MPC555 Subsequently application programs like Car Following and Obstacle Avoiding are to be implemented too The main hardware materials given for this project were a MPC555 Control Board from Robosoft manufacturer of Cycab a SICK LMS 291 S05 a SUN workstation and a LINUX Windows NT PC for programming and downloading of programs to MPC555 Additional materials include RS232 RS422 cables and user manuals for SICK LMS and MPC555 During the initial 2 months of the attachment the main work involved was to have a good understanding of the MPC555 SICK LMS reviewing of C programming theory and setting up the test environment Tests were also done on the 2 hardware with programs written in C programming language The following 2 months w
8. it will capture the 1 response byte and determine if it is an ACK byte If so it will continue capturing the rest of the message by SICKGetMsg Otherwise if it is a NAK or rubbish error has occurred and the program will proceed to UARTClose 0 where the UART interface of the MPC555 will be closed After getting the entire message the function SICK_CRC_Check will create a CRC value based on the entire message block except the received CRC bytes Then the received CRC bytes will be converted into decimal format CRCL CRCH x 256 Both received and created CRC values will be compared and if they are the same the program will continue Following command strings are sent to control the LMS to commence with a scan 180 scan and 0 5 angular resolution by default and to send back the scan data 361 values to the MPC555 Figure 2 5 2 2 shows the process of capturing the 361 scan values in the main program First of all SICKInit3 is sent with the request of all the scan data values continuous The same process as the earlier functions is run though SICKChkACK SICKGetMsg and SICK_CRC_Check This time after the MPC555 receives the message that the request for all 361 scan values was successful by SICKGetMsg the sending will not stop there The LMS will proceed to send another string of data beginning with STX no ACK or NAK byte for this and this string contains all the 361 values Also since each scan value consists of 2 bytes th
9. k k k kK XK k kK k k X k k k k k k k w E AS A A A AMA 400 04 A A A AA 12820A A0 a do CENE 40071027 SAA Je Start of main program JE AAA AAA AAA AA AAA O 2907554725470007 ER E LRAREREEEE ESSE ES EEEEEEREE RK NMRNALNNNN REKKA RAMA AM RAENHN NAMNA KLAN AMMAR RENE int main char Buffer BufSize int Response UARTInit 1 19200 8 1 0 amp Buffer BufSize For communication with another terminal to show certain responses Response UARTInit 0 19200 8 1 0 amp Buffer BufSize if Response 0 LCDInit LCDPutString UARTInit OK UARTPutString 1 n rHello UART Serial Interface PERFECT UARTPutString 1 n rPress Ctrl D to continue LCDClear LCDPutString Start SICKInit LCDClear else LCDInit LCDPutString UARTInit Error UARTClose 0 PEA Commence SICK Initialisation and Recv Data eh if SICKInit LCDPutString Part1 ok Trial For FALCO if ISICKChKACK SICKGetMsg LCDPutString Part2 ok Trial For FALCO if SICK_CRC_Check 0 ICRC16 Check LCDPutString Rep1 Revd OK LCDClear if ISICKInit2 if ISICKChkACK SICKGetMsg if SICK_CRC_Check 0 LCDPutString Rep2 Revd OK LCDClear f ISICKInit3 if ISICKChKACK SICKGetMsg SICK_CRC_Check if SICK_CRC_Check 0 D6 LCDPutString Rep3 Revd Ok LCDClear SICKGetData if SICK_CRC_Check 0 LCDPutString
10. looks into the implementation work done on the serial interface Then Chapter 3 will present the application programs being done currently Comments and discussions are given in Chapter 4 Finally the report ends with the Summary and Conclusion in Chapter 5 INTRODUCTION Since the invention of automobiles the automobile industry has grown tremendously Subsequently the technology involved has also improved by leaps and bounds The introduction of gears to the once single gear vehicles and the increase of engine horsepower are just some good examples of technology advancements made in the automotive field These leaps in the technology not only bring greater convenience to the people they have also generated other interests These interests especially in speed and engine power have been so great that the industry is now manufacturing faster and more powerful cars However power is nothing without control Lives are lost everyday on the road due to automobile accidents Even with the latest technology and safety precautions the legendary World Formula 1 Champion Artyon Senna died in a fatal crash when his racecar crashed into a concrete wall at 300 km h All these have prompted the automobile industry to look more into improving the safety features of a car At INRIA Rhone Alpes researchers are currently working on an intelligent vehicle named the Cycab lt is compact environmentalfriendly and can operate autonomously with minimal
11. menu the program will be user friendlier and running of the application programs can also be included in the menu 4 4 Minor Problems Encountered During the course of work with the SICK LMS there were often instances of insufficient power to power the LMS In fact the LMS is a big consumer of energy and this actually shortens the life span of the battery run time Thus it is suggested that the battery of the Cycab be recharged after it is being used for a fixed period of time For the MPC555 it has a problem of hardware reset not working Sometimes when a program hangs midway while processing in the MPC555 doing a hardware reset of the MPC555 will not reset and clear all the buffers Power to the MPC555 has to be cut off completely for a few minutes before the MPC555 can operate again This problem will be reported to Robosoft for their action 112 CHAPTER V INRIA Rhone Alpes CHAPTER V SUMMARY AND CONCLUSION For this period of Industrial Attachment with INRIA Rhone Alpes the project given was very good with a clear objective and direction Till this moment the goal of implementing a high speed serial interface between the MPC555 and the SICK LMS had been achieved Although tests at the initially proposed 500 Kbauds were not carried out due to problems with the MPC555 board provided tests at lower baud rates were done under the direction of my supervisor Also the program written to implement the serial interfac
12. of thousands of people each year throughout the world especially young adults and the elderly Although safety has improved by one order of magnitude in the last decade through better infrastructure and safer cars the rate of improvement has tapered off The techniques to improve drastically the safety are based on four approaches Driver monitoring and warning e Partial control of the vehicle in emergency situations e g Brake system e Total control of some of the functions of the vehicle e g Speed e Total control of the entire vehicle 1 1 3 2 Minimisation of Energy Consumption Fossil fuel is limited and consumption of it has only increased every year thus threatening the supply Drastic reductions in the consumption of fossil fuels are one of the challenges for everyone in the next twenty years Road transportation has always been playing the dominant role in the consumption of these fuels and the trend is going up through two factors the increase in freight transport by road and a very high increase in car ownership in emerging countries Without a radical departure from existing technologies and practices the goals set by the countries 64 cannot be met Thus new high technology cars running on electricity can be one of the solutions 1 1 3 3 Minimisation of Pollutions and Nuisances In all large cities through the world air quality is now monitored at frequently unacceptable levels Noise levels in cities and near hig
13. process the scan data values When the LMS sends the scan values back to the Host MPC555 it is capable of sending the data in different format type Allthe measured data sent by the SICK LMS come from the following information e The angle of emitting laser beam e The distance e The level of intensity of the reflected beam The data processing by the LMS will provide the following information e Data values of 1 complete scan in polar coordinates and the intensity level of the reflected beam e Averaged values e Partitioned values e Averaged partitioned values e The shortest perpendicular distance with respect to the radius of the scan e The shortest distance value in each segment e Cartesian coordinates Figure 3 2 1 1 below illustrates a typical process of the extraction and processing of scan data by the LMS Selection Filtering of Processin of data required g of data 106 Fiqure 3 2 1 1 Extraction and Processing of Data 3 2 2Detection of Reflector Target The SICK LMS detects the distance of objects in front of it by the principle of time of flight as explained in Chapter 1 3 2 This implies that the total time taken br the emitted laser beam to reach the target and for the reflected laser beam to return to the captor multiplied by the speed of light constant will produce the distance Though the SICK LMS is able to detect most objects in front of it the intensity of the reflected laser beam detected by
14. related options CFLAGS mpowerpc mhard float gdwarf SRC source filess and OBJ object files variables list the files needed to generate the main elf executive SRC Serial1 c TMP SRC c 0 OBJ TMP s 0 Makefile commands all make Serial1 make download 0 C XGCC 02 c lt 0 0 S XGCC 02 c lt 0 0 Serial1 OBJ crt0 o LDSCRIPT XGCC LDFLAGS CFLAGS OBJ o LIBDIR LIB clean RM o Seriali Serial1 map Serial1 bin download ROBOTIQUE bin linux elf2sdxbin Serial1 Serial1 bin dwnbin testall bin 16404 D8 D9 TABLE OF CONTENTS Page ABSTRACT i INTRODUCTION ii ACKNOWLEDGEMENT iv LIST OF TABLES v LIST OF FIGURES vi LIST OF PHOTOS vii CHAPTER I 1 INTRODUCTION TO HARDWARE 1 1 1 Cycab 1 1 1 1 System Description and Specifications 1 1 1 2 Mechanics and Electronics New Cycab 4 1 1 3 Goals of Cycab 8 1 1 3 1 Increase Safety of Road Transportation 8 1 1 3 2 Minimisation of Energy Consumption 8 1 1 3 3 Minimisation of Pollutions and Nuisances 9 1 1 3 4 A More Pleasant Living Environment 9 1 2 Motorola MPC555 9 1 2 1 Microprocessor Description 10 1 2 2 Features 10 1 2 3 Queued Serial Multi Channel Module QSMCM 11 1 2 4 Two CAN 2 0B Controller Modules TouCANs 12 1 3 SICK LMS Laser Measurement System 15 1 3 1 System Description 15 1 3 2 Operating Principle 16 1 3 3 Specifications LMS 291 S05 18 1 3 4 Features 19 D10
15. the above Table 2 3 3 1 the LMS telegrams sent or received can be interpreted and verification functions can also be written 2 3 4 Example of Telegram Transfer To have a clearer picture of the telegram structure an example of a sent telegram and a received telegram extracted from one of the serial interface test programs done is described here 2 3 4 1 Command sent from MPC555 Host to LMS LOW HIGH BEH C5H Table 2 3 4 1 Command Telegram sent from MPC555 to LMS 2 3 4 2 Interpretation of Command Telegram E Start character for intialisation of transmission pa LMS address Broadcast addr to all LMS Length of data bytes 10 CMD Data Command byte for Select Change of Operating Mode Operating Mode Installation mode for config and setting parameter 89 JE Installation mode default password SICK_LMS C5BEH CRC16 Checksum return value Table 2 3 4 2 Interpretation of Command Telegram 2 3 4 3 Response sent from LMS to MPC555 Host Table 2 3 4 3 Response Telegram sent from LMS to MPC555 2 3 4 4 Interpretation of Response Telegram Acknowledge character when response is received correctly within 60 ms Otherwise 15H NAK Not Acknowledged will appear C Start character for intialisation of transmission CE LMS address Broadcast addr to all LMS 80H E Length of data bytes 3 CMD Data Status Or Command byte for Response to Select Change of Operating Mode E Response Status
16. 1 3 5 Possible Applications for SICK LMS 19 1 3 6 LMI 400 20 CHAPTER Il 22 IMPLEMENTATION OF REAL TIME SERIAL INTERFACE 22 2 1 Real Time Serial Interface 22 2 1 1 Serial Interface 23 2 1 2 Serial Format 23 2 2 MPC555 Control Board 25 2 2 1 UART Serial Interface Functions in C Language 25 2 2 2 MPC555 Interface Ports 26 2 3 SICKLMS 29 2 3 1 LMS Telegram Structure 29 2 3 2 Organisation of Telegrams 31 2 8 3 Structure of LMS Status Byte 32 2 3 4 Example of Telegram Transfer 33 2 3 4 1 Command sent from MPC555 Host to LMS 33 2 3 4 2 Interpretation of Command Telegram 33 2 3 4 3 Response sent from LMS to MPC555 Host 34 2 3 4 4 Interpretation of Response Telegram 34 2 8 5 CRC16 Checksum and Other Verification Methods 35 2 3 6 The Makefile 36 2 4 The Simulated Environment 38 2 5 The Flow of Program 39 2 5 1 Data Exchange between SICK LMS and MPC555 39 2 5 2 Main Program Flow 42 D11 CHAPTER Ill 47 PROCESSING OF SCAN DATA AND APPLICATION PROGRAM 47 3 1 Obstacle Avoidance 47 3 1 1 LMS Programmable Scanning Field 47 3 1 2 Implementation of Obstacle Avoidance 48 3 2 Car Following 49 3 2 1 Extraction and Processing of Data 49 3 2 2 Detection of Reflector Target 50 3 2 3 Mathematical Algorithm 51 CHAPTERIV 53 COMMENTS AND DISCUSSIONS 53 4 1 Limitations of Cycab 53 4 2 Processing Time 54 4 3 Addition of a User Menu 55 44 Minor Problems Encountered 55 CHAPTER V 56 SUMMARY AND CONCLUSION 56 REFERENCES 58 APPENDIX A A
17. 55 ID in decimal This entire process will take place when the user does a Make Download command or Makefile command For the complete Makefile program please refer to Appendix E 94 2 4 The Simulated Environment The SICK LMS is connected to the MPC555 via RS232 RS422 cable to port COM 1 The Figure 2 4 1 below illustrates the overview of the entire setup In the case of this project a Linux PC was used in programming compilation and downloading of the completed software into the MPC555 Thus the simulated environment is in fact the same as the actual environment on the new Cycab FALCO Infinity series computer was used during the testing and simulation process of the serial interface program It is mainly used for inputting responses to the MPC555 and viewing responses from the LMS Sends command to LMS via RS422 LMS MPC555 Transmit scan data CAN Bus RS422 at under real time CAN 1 Receives LMS data in real time 38 4Kbau conditions via RS422 j RS232 at 38 4Kbau FALCO Infinity Series Computer Figure 2 4 1 Overview of Simulated Environment 95 2 5 The Flow of Program 2 5 1 Data Exchange between SICK LMS and MPC555 In this C program of the implementation of a realtime serial interface there are a lot of data flow between the LMS and the MPC555 These exchanges of data may be confusing and the LMS is programmed in an orderly manner such that the initialisation request and receipt of data are in
18. 81 2 2 2 MPC555 Interface Ports In order for MPC555 to be able to communicate with the LMS the MPC555 s COM serial port has to be initialised The MPC555 control board used in this project has 6 ports 2 CAN Bus ports 3 serial ports and 1 free port refer to Photo 2 2 2 2 The written program was downloaded into the MPC555 control board via the CAN port 1 The new Cycab will be based on a Linux PC Personal Computer installed with a CAN Interface Card and all the main nodes of the Cycab will be connected by CAN bus to the MPC555 48 VDC Power PE A Y Data List po 5 RS 232 or RS 422 to SICK LMS Photo 2 2 2 1 MPC555 Control Board with Connections Top However due to hardware incompatibility between the port interface card and MPC555 the maximum baud rate that the port can handle is about 250 Kbauds whereas the minimum baud rate for real time data transfer must be at least 500 82 Kbauds Thus the serial interface was being tested at 19 2 Kbauds instead until Robosoft provides a new port interface Serial CO CAN Port 1 Photo 2 2 2 2 MPC555 Control Board with Connections Front 83 24 VDC Power Supply AA RS232 or 14 RS422 from MPC555 Indicator lights Photo 2 2 2 3 SICK LMS with Connections Top Photo 2 2 2 3 above shows a top view of the SICK LMS attached to the Cycab It can be seen that the RS232 RS422 cable from the MPC555 are connected to the right por
19. Change of operating mode of the LMS Select Change of configuration of the LMS Request for measured scan values Request for LMS status data Request for LMS configuration data e Telegrams from LMS to Host Response telegrams by LMS with respect to telegrams sent by Host In addition when request telegrams are sent from Host to LMS a software handshake will be initiated by the LMS Upon the receipt of a correct request the LMS will send out a character ACK 06H before the entire response message However in the case that an error is detected the LMS responds with a NAK 15H 87 For synchronisation purposes the time interval allowed between 2 bytes of data in a telegram is between a minimum of 55 us and a maximum of 6 ms When violated the telegram will be ignored For a more complete list of telegrams for the LMS refer to Appendix A 2 3 3 Structure of LMS Status Byte The status byte consists of 8 bits As seen from the figure below the status byte gives useful information like Error encountered if any or other problems like Pollution Combination of bits 0 1 and 2 are used to produce values 0 4 Meaning no error info warning error fatal error Bits 3 and 4 produce data source designators 00 01 10 11 LMS xx1 to xx4 LMI LMS xx6 Reserved State of RESTART input 1 HIGH 0 LOW Implausible measured value 88 Table 2 3 8 1 Description of LMS Status Byte With
20. NANYANG TECHNOLOGICAL UNIVERSITY REPORT ON INDUSTRIAL ATTACHMENT WITH INSTITUT NATIONAL DE RECHERCHE EN INFORMATIQUE ET EN AUTOMATIQUE INRIA RHONE ALPES FRANCE 8 JAN 2001 24 JUN 2001 PREPARED BY TAN POK KIAM 980695B03 EEE 3 ABSTRACT This report presents the project done during the Industrial Attachment with the French national research laboratory Institut National de Recherche en Informatique et en Automatique Rhone Alpes France INRIA Rhone Alpes The project looks into implementing a real time serial interface between 2 hardware namely the Motorola MPC555 microcontroller and the SICK LMS Laser Measurement System on the Cycab This is to enable the Cycab to have a real time laser sensor guiding system Work was done on programming the MPC555 to communicate with the SICK LMS Numerous tests were also done to look into the response of the LMS when different sets of telegrams were sent Once the real time serial interface was implemented work was concentrated on writing application programs for the SICK LMS and MPC555 Application programs like Car Following and Obstacle Avoidance are currently in the process of implementation This report is divided into 5 Chapters An introduction of the project with the objectives work and hardware involved will be given first After that the first Chapter will present a more detailed introduction of the main hardware used in the project In the following Chapter this report
21. NOR NO TO a AA ee SICKInit3 SICK LMS Command String3 Request LMS to send all scan continuously JARRE EERE S NEN REESE EREEER ELLE EE EEES EEEEERELERE SEES RENE FER SR ESSE EAERES REE EEES int SICKInit3 for i 0 i lt 8 i unsigned char init3 8 0x02 0x01 0x02 0x00 0x20 0x24 Cre_ Create Send SICKCreateCRC amp init3 0 6 init3 6 unsigned char Cre Create Send 8 OxFF init3 7 unsigned char Cre_Create_ Send gt gt 8 res UARTPutChar 0 init3 i if res 0 LCDPutString Msg Sent to SICK LCDClear else LCDPutString Msg Send Error return 0 JERRERERRAERAERER ERES AAA ARE EEE EE REE ELERE REET NERER RARAS ARA RAE RRAA NAMAN RMA KN MURARIA NAS A E e SICKChkACK To check the 1st byte of the response message for ACK PERA RO OO RR define ACK 0x06 define NAK 0x15 int SICKChkACK unsigned char ack ack 0x00 UARTGetChar 0 8msg 0 ack msg 0 while ack ACK amp amp ack l NAK LCDPutString ChkACK Err XX LCDClear return 1 if ack NAK LCDPutString ChkACK Err NAK LCDClear else llack ACK msg 0 0 return 0 D4 ERRE EE EERE TEE EEE ARERR EE EE Ee Ree ee eee Pe ep eg hy PRCT TE TE ECE Care NS Se Do E SICKGetMsg To get the entire response message from LMS JS SRE RAR ERSESERSER ESSERE LEER ERED EEE REERE ARNE REE EER KEKEN LE EERE RE RRR AAA RAR ERE NA ELENA EEE E
22. Oper Mode change successful Status byte pS CRC16 Checksum return value Table 2 3 4 4 Interpretation of Response Telegram 90 An important point to note and remember is that no Status byte is transmitted when a request command is sent to LMS The Status byte is included only when the LMS is transmitting response messages Also for responses from LMS an ACK byte will be included before the STX byte The Len bytes when converted from hexadecimal to decimal give the number of data bytes that are enclosed within the 2 red lines 2 3 5 CRC16 Checksum and Other Verification Methods In ensuring transfer reliability a block check is done at the end of the telegram with a CRC checksum over the entire data package with CRC 16 polynomial generator CRC Cyclic Redundancy Check is a common method for detecting data transmission errors The CRC will perform a mathematical calculation on the data block to be sent and generates a unique checksum value that represents the content and organisation of that data Subsequently the receiving station also generates a checksum value of the received data based on the CRC algorithm Then both CRC checksum values at the sending and receiving stations are compared to make sure that they are the same If they are different it can be concluded that errors occurred during the sending process During the software handshake refer to Chapter 2 3 2 Organisation of Telegrams the LMS does nothing if the wron
23. PEER EPEE Pr Nn 14 29 20 N en E PANAIA EEE cel I O hn o arte ot D 220427072 ate Error the combination Parity nBit nStop is not equal to 9 or 10 10 and 11 bit frame with Start bit gi define err_UARTFrame 1 define err_UART 2 Error UART number must be 0 or 1 define err_UARTNOChar 1 NO Char present in the buffer int VARTPutString int UartNb char St int Result 0 while St 0 0 amp amp Result 0 Result UARTPutChar UartNb St 0 St return Result B2 LCD Routine To display a string of char on LCD screen JEL2 A Bo sett VEEE RAE EE APA T din int LCDPutString char St int Result 0 while St 0 0 amp amp Result 0 Result LCDPutChar St 0 St return Result Ps N e A DE eS SE e ee E el eE E di LCD Command see documentation of HDD44780 A E AAA A define Icd_Clear 0x01 define Icd_CursorHome 0x02 define lcd SetAddress 0x80 define Icd_SetAddrL1Home 0x80 define lcd SetAddrL2Home OxCO define err_ErrorLCD 1 Error returned when busy flag is ALWAYS set EE PR PRE EE AC EE RE PP AE ER AE PEER RER ER ADC channel assignment see schematic for more detail V a EEEE ERA SEE eee ke sees RER ARRET RER RE RER define adc_VAxe1 8 define adc_VAxe2 9 define adc_VAxe3 10 define adc_VAxe4 11 define adc_ Temperature 12 define adc_Temperature2 13 define adc_Temperature3 14 define adc_Temperature4 15 RE eet e
24. PPENDIX B APPENDIX C APPENDIX D APPENDIX E D12 D13
25. Scan Values Revd LCDClear else LCDPutString Val revd error LCDClear UARTClose 0 else LCDPutString Rep3 Error LCDClear UARTClose 0 else LCDPutString Rep2 Error LCDClear UARTClose 0 else LCDPutString Rep1 Error LCDClear UARTClose 0 D7 APPENDIX E The Makefile kkkk k k kK kH k k k KK KKK k K KKK kK Xk k K Kk k Kk k kK KK kK kH k kK k kK k k kK kH k kK k k k k k k kK k k kK k kK k K k kK kk k k k kK k kK k kK kK k k k k k k kK k k k k k k k c ROBOSOFT pierre robosotft fr This is a Makefile used to compile programs for MPC555 targets Modified Tan Pok Kiam Moyens Robotique INRIA Rhone Alpes kkkk k k kk k K k kK H kK K k kK K K k k kK Xk kK Kk k k k Kk k kK XK k kK H kK KKK k K k k kK Xk K XK k K k kK XK kK kK K k K K XK K kK k kK X kK X gt k kK X k kK X K XK k kK k k k k k k k k SHELL bin sh SUFFIXES s c o RM rm f ROBOTIQUE local projets robotique Specify MPC555 cross GCC compiler XGCC ppc elf32 gcc XGCC ROBOTIQUE bin linux ppc elf32 gcc Set libraries path and the list of libraries to be passed to the linker LIBDIR L ROBOTIQUE MPC555 lib LIBDIR L home ciney lydoire local lib LIB Im Ic Inode555 Linker options passed from compiler to linker LDSCRIPT script ld LDFLAGS WI T LDSCRIP T Map map Hardware configurations Target
26. a ai a2 2 argsin yo y1 dc 108 where x and y Cartesian coordinates of the leading vehicle relative to the following vehicle d Direct distance between the 2 vehicles with respect to the centre of the vehicle Angle between the longitudinal axis of each vehicle a Angular position of the leading vehicle with respect to the front of the following vehicle dc Distance between the 2 reflector targets Cy and C2 The program will filter aside all the required values like the Cartesian coordinates in order to get the 3 required values for Car Following application Both applications are currently in the process of implementation 109 CHAPTER IV COMMENTS AND DISCUSSIONS 4 1 Limitations of SICK LMS The current laser sensor used SICK LMS conducts a scan of up to 180 and a high angular resolution of 0 25 It is configurable from the type of scanning field required to the type of scan data value the user wants to retrieve However its drawback is that the scan is only in planar form Thus the laser scanning zone is like a flat piece of paper cutting across the area in front This may pose some problems like the height of obstacles or reflecting beacons must not be too short or too high They must coincide with the line of sight of the LMS laser beam This problem was actually encountered when tests were done on the Cycab The securing screws on the SICK LMS that attaches the LMS to the front of Cy
27. a proper sequence Basically the data exchanges are categorised into the following parts in sequence in the program 1 The configuration operating mode data of LMS 2 The specification parameters of LMS measurement 3 The scan values data Select Change of configuration operating mode MPC555 Interface Port Data of operating mode changed Figure 2 5 1 1 Request for Change in Operating Mode with Response 96 Select Change of configuration operating mode MPC555 Interface Port Figure 2 5 1 2 Request for Change in Operating Mode without Response Request for measured values continuous Data of successful request of values MPC555 Interface Port Scan values 361 Figure 2 5 1 3 Request for Scan Values continuous 97 Figure 2 5 1 1 shows a flow diagram of a good request for Select Change of Configuration Operating Mode Upon verifying that the request is good an ACK byte is sent followed by the mode changed data An example of a bad request with incorrect CRC is shown in Figure 2 5 1 2 No data is transferred after the NAK byte is sent For the Request of Scan Values continuous the normal procedure takes place Figure 2 5 1 3 with the request sent to LMS and after verification ACK is sent back to MPC555 Following the ACK the normal response message describing a successful request for scan values is sent After that the scan values will then be sent Depending on the scan angle and th
28. be given Basically it will be split into 3 main parts the first will explain the realtime serial interface followed by the explanation of the serial functions of the MPC555 The final part shall look into the description and explanation of programming the SICK LMS 2 1 Real Time Serial Interface The present Cycab based on the older Motorola MC68332 microcontroller without CAN bus support is programmed only to handle data transfer rate of 9 6 Kbauds between the equipped LMS and a laptop Also the MC68332 microcontroller does not have a CAN bus interface which limits the number of devices that it can control With the new Cycab the new generation MPC555 microcontrollers can handle up to a maximum data transfer rate of 1250 Kbauds which is more than sufficient to have real time data transfer between the MPC555 and LMS To have real time data transfer a minimum baud rate of 500 Kbauds is required Sends command to LMS via RS422 LMS MPC555 Transmit scan data l RS422 at under real time Receives LMS data in real time 500 conditions via RS422 Figure 2 1 1 Configuration of Required Serial Interface 78 2 1 1 Serial Interface The serial interface for the real time data transfer is of type RS422 However due to a hardware incompatibility problem refer to MPC555 Interface Port between the port interface card and the MPC555 RS232 was being used in the project RS means Recommended Standard Both RS232 and RS422 a
29. ber to the CAN bus ports and the serial COM ports as these designations are crucial during the implementation of the serial interface 70 1 3 SICK LMS Laser Measurement System 1 3 1 System Description The LMS Laser Measurement System 291 S05 is a divergent laser scanner with a maximum scanning angle of 180 and a lateral resolution of between 025 and 1 variable and definable Also the laser scan is a planar scan The accuracy of measurement in a single shot is about 2 cm With respect to the data transfer rate the LMS is capable of transferring all measured values in real time via serial interface at a baud rate of 500 Kbauds Photo 1 3 1 1 LMS 291 S05 In this project the LMS291 S05 used is shown in the above Photo 1 3 1 1 71 1 3 2 Operating Principle The operating principle of our non contact Laser Measurement System LMS is based on time of flight measurement The LMS calculates the distance to the object using the time of flight of pulsed light i e the length of time between sending and receiving the beam of light Figure 1 3 2 1 An extremely short pulse of light infrared laser beam is transmitted towards an object Part of the light is reflected back to the unit after a fraction of a second later A rotating mirror deflects the pulsed light beam to many points in a semi circle The precise direction is given by an angular sensor on the mirror laser RADAR A large number of coordinates measu
30. cab are not tight enough This problem along with the weight of the LMS pulls and tilts the LMS down Though the range of tilt is not big less than 1 cm at the point of attachment this difference in height is greatly magnified at a further distance from the Cycab This caused the inability of the laser to reach the desired target If the tilt height difference is greater than the height of the reflector target of the leading Cycab in a Car Following application the LMS will not be able to detect the reflectors and the application will fail Therefore a proposed solution would be to increase the overall reflector height or to implement a more secure attachment system for the SICK LMS 110 Furthermore with scan data from a planar scan it is only possible to plot out a 2 Dimensional 2D plan of the specified scanning field Though a 2D plan may prove just sufficient for Obstacle Avoidance application the user will not be able to know the obstacle s size shape and other features that may allow the user to have more decision making choices For example if a large truck is in front of the Cycab the user may either want the Cycab to slow down and keep a longer safety distance or take another available route Thus a simple 3 Dimensional 3D plan model of the specified scanning field can provide much more data and extend the uses of the application further Pattern comparison e g compares the shape size of obstacle can then be
31. ctions aided driving and autonomous driving Aided driving relies on the use of a joystick and a finger touch screen This joystick is connected to the computer which controls the vehicle and then provides secure and easy driving In addition soeed may be limited in curves and special areas like narrow lanes to improve safety of the vehicle The control of the Cycab is simple and user friendly and everybody will be able to drive this vehicle without any special skills The finger touch screen allows the user to communicate with the system in order to get information such as localisation vehicle autonomy or even a list of nearby restaurants One possible application for the Cycab is to form a virtual car train of empty vehicles with only one driver in the first vehicle also Known as Car Following Other autonomous driving modes like radio control or light markers guidance may be implemented and research is currently undergoing in INRIA 54 The Cycab has been designed with mass production and public use constraints in mind These considering factors are low cost compactness robustness and easy maintenance The whole design has been oriented in this way from the mechanics to the computer based system 300 kg 4 x 1 kW Electric Motors Drive 4 WheetDrive 4 Wheel Steering System Maximum 30 km h Speed Range 40 km 2 adults luggage Modes of e Manual driving with joystick Operation Fully automated driving e Teleoperat
32. ding command to LMS no status message is transmitted CRC checksum for entire data Table 2 3 1 2 Description of LMS Telegram Structure With reference to the above tables it can be seen that a typical telegram sent to LMS consists of the following bytes in sequence STX ADR LEN Low LEN High CMD N x Data Status CRC Low CRC High One very important definition to note is the 2 Len bytes which describes the length of the following data bytes except the CRC bytes That means the Len bytes refer to the total number of bytes in CMD Data and Status only Caution must be taken not to confuse these data bytes with the actual N x Data bytes As the number of Data bytes N sent is different every time thus it is necessary to read the Len bytes and minus off 2 bytes CMD and Status in order to get the number of Data bytes In this project the defined address ADR of the SICK LMS is 0x01 01H 1 86 2 3 2 Organisation of Telegrams In order to establish a good communication interface between the SICK LMS and a Host system MPC555 in this project a comprehensive list of different telegrams doing different functions is required These telegrams can be organised into 2 main categories by their direction of data transfer Host to LMS and LMS to Host Subsequently the telegram list can be furthur categorised into the following different sub categories e Telegrams from Host to LMS Initialisation and Reset of the LMS Select
33. e QSMCM provides 3 serial communication interfaces namely the Queued Serial Peripheral Interface QSPI and 2 Serial Communication Interfaces SCI1 and SCI2 The dual independent SCIs are used to communicate with external devices and other MCUs via an asynchronous serial bus Each SCI is a full duplex Universal Asynchronous Receiver Transmitter UART serial interface For the implementation of a high speed serial interface between the SICK LMS and MPC555 the UART serial interface function of the MPC555 was used Robosoft also provided some C libraries specific for MPC555 which aided in the programming part of the implementaion The SCI baud rate bits sec can be programmed by writing a 13 bit value to the SCxBR field in the SCI control register The baud rate can be calculated as follows SCI Baud Rate fsys 32 x SCxBR 67 Where SCxBR is in the range of 1 2 3 8191 Nominal Baud Rate Actual Baud Rate Value of SCxBR 1250000 00 1250000 00 57600 00 38400 00 32768 00 28800 00 19200 00 14400 00 9600 00 4800 00 2400 00 56818 18 37878 79 32894 74 29069 77 19230 77 14367 81 9615 38 4807 69 2399 23 1 36 rr 7 0 03 1200 00 1199 62 600 00 600 09 2083 300 00 299 98 4167 Table 1 2 3 1 Possible Baud Rate for 40 MHz System Clock 1 2 4 Two CAN 2 0B Controller Modules TouCANs The MPC555 contains 2 CAN 2 0B controller modules TouCAN Each TouCAN is a
34. e Test Program ON RE Et re A de Test_Serial c UART Interface Test Platform Author Tan Pok Kiam Moyens Robotique INRIA Rhone Alpes To test send request receive response determine response byte position A EET ERENEREERERERARERERERARERERERERENEEPEREEEENEERERERELANAREEERE include lt math h gt define BufSize 128 int UARTPutString int UartNb char St int Result 0 while St 0 0 88 Result 0 Result UARTPutChar UartNb St 0 St return Result int LCDPutString char St int Result 0 while St 0 0 88 Result 0 Result LCDPutChar St 0 St return Result int main char Buffer BufSize char c 0 double d int i res unsigned char init 7 0x02 0x00 0x01 0x00 0x10 0x00 0x00 Test Request UARTInit O 19200 8 1 0 amp Buffer BufSize LCDInit LCDPutString Part1 OK MPC555 UART Initialisation OK for i 0 i lt 10000 i d cos d LCDInit for i 0 i lt 16 i res UARTPutChar 0 init i if res 0 LCDPutString Request ERROR i LCDInit LCDPutString Part2 OK Test Request Send Successful C1 for i 0 i lt 10000 i d cos d LCDInit for i 0 i lt 10 i LCDPutChar res UARTGetWaitChar 0 amp c Receive Test Response if res 0 LCDPutString Receive ERROR LCDPutChar c LCDInit LCDPutStrin
35. e angular resolution chosen the number of scan values will differ For this project the default scan angle of 180 and angular resolution of 0 5 was chosen Thus 361 scan values will be sent Refer to Table 1 3 3 1 for details of number of scan values The retrieving of the 361 values after a request for the scan values will be explained in more detail in the next section 2 5 2 Main Program Flow 98 2 5 2 Main Program Flow UARTInit Initialise UART Return 1 serial interface of MPC555 Return 0 SICKInit Initialise LMS Return 0 Return 1 SICKChkACK Return 0 SICKGetMsg Return 1 SICK_CRC_Check Return 0 SICKInit2 Chg of Baud Rate Similar Process Figure 2 5 2 1 Initialisation Flow of Main Program 99 SICKInit3 Request LMS to Return 1 send all scan values continuosly Return O Return 1 SICKChkACK Return 0 SICKGetMsg Return 1 SICK_CRC_Check Return 0 SICKGetData Return 1 SICK_CRC_Check Return 0 Application Data Treatment Figure 2 5 2 2 Capturing of Scan Values in Main Program 100 As mentioned earlier in Chapter 2 5 1 the data exchange between SICK LMS and MPC555 can be categorised into 3 categories and the main program can also be categorised in the same way In Figure 2 5 2 1 the initialisation of the UART interface of MPC555 and SICK LMS is shown and this is the first part of the main program The UART was first initialised by UARTInit and if the ret
36. e ee ee e ea ee A A Se EE eae See ee eens define BufSize 16 Buffer Size define nMoy 64 Average number int main char Buffer BufSize For RX char Ch char St 31 B3 int VMoy nMoy int Val Value int J int chAdc int axis int EncVal short int pwmcmd 0 int direc ADCInit LCDInit TPU3Init PWMInit InitInterrupt Ox800 UARTInit 0 9600 8 1 0 amp Buffer BufSize UARTPutString 0 n rUART 9600 Baud ADC Chain calibration by Robosoft SA LCDPutString PoKklaM amp MpC555 chAdc 0 for 1 0 lt nMoy I VMoyll 0 Value 0 l 1 while 1 DACWrite 0 1 DACWrite 3 1 amp OxFFF DACWrite 1 0x0400 l 1 10 amp OxFFF ADCRead chAdc adc_VAxe1 amp Val Val Val 512 Value Value VMoy nMoy 1 for J nMoy 1 J gt 0 J VMoy J VMoy 1 VMoy 0 Val Value Value VMoy 0 Val Value nMoy B4 if UARTGetChar 0 amp Ch err_UARTNoChar if Ch POTSet chAdc 1 if Ch POTSet chAde 1 UARTPutChar 0 Ch direc OxOF EncRead 0 amp EncVal if EncVal 0 UARTPutChar 0 X if UARTGetChar 0 amp Ch err_UARTNoChar if Ch 1 pwmcmd if Ch 2 pwmcmd if Ch d direc direc WritePWMlO direc UARTPutChar 0 Ch PWMWrite 0 amp pwmcmd return 0 B5 APPENDIX C Serial Interfac
37. e total length of the entire string is 361x2 4 726 bytes The additional 4 bytes are the CMD Status LENL and LENH 102 After getting the entire string of scan values a CRC check is done again and then the program will go to the next part treatment of the scan values for Application programs like Car Following and Obstacle Avoidance The complete program on the serial interface can be found in Appendix D 103 CHAPTER lll PROCESSING OF SCAN DATA AND APPLICATION PROGRAM In this third Chapter the report will focus on the method of data extraction for processing and the application programs Obstacle Avoidance and Car Following A researcher did before some previous work on the above for the old Cycab equipped with the MC68332 microprocessor The objective now is to translate these into a suitable format for the MPC555 microcontroller installed in the new Cycab 3 1 Obstacle Avoidance 3 1 1 LMS Programmable Scanning Field As explained earlier in the Chapters 1 and 2 the SICK LMS can be requested to change its operating mode baud rate type of data to be sent method of data sending e g continuous and many others In fact the LMS can be instructed to define its scanning field Figure 3 1 1 1 below illustrates 4 possible configurations of scanning field Configuration 1 is the normal configuration where the laser from LMS makes either a 100 or 180 scan Configuration 2 and 4 are a defined scanning field where a desir
38. e works well at the other lower baud rates so there should not be much problem for real time interfacing The next objective of implementing application programs Obstacle Avoidance and Car Following for the Cycab is currently being carried out These applications involve programming the MPC555 and the SICK LMS to conduct and collect different scan data thereby making use of the implemented serial interface too These implementations of application programs will be achieved by the end of the attachment Due to the numerous functions that the SICK LMS can do there were a lot of confusion and doubts over the functions of the telegrams However tests done while implementing the serial interface provided results that helped clear some of the doubts and they were documented in this report as well On the whole this project involving both hardware and software implementation has been very fruitful A lot of experience was gained in working with hardware interfacing and the hardware software implementation Due to the different nature of the 56 CHAPTER V INRIA Rhone Alpes hardware involved it was necessary to have a clear basic understanding of them in a very short time This taught me the skills of filtering out the more important theory and information whenever there is a need to work with new hardware In addition the importance of good and clear documentation of hardware specifications theory and correct procedures was also app
39. ed area is marked out The LMS can be programmed to define the scanning field in a rectangular field or a semi circular field Furthermore up to 3 scanning fields can be configured active simultaneously and this is shown as configuration 3 3 Fiqure 3 1 1 1 Possible Configurations of LMS Scanning Field 3 1 2 Implementation of Obstacle Avoidance The purpose of an Obstacle Avoidance application is to implement a safety feature to the Cycab where it will either stop or move out of the way when an obstacle is detected This application is simple in terms of data extraction and processing as it does not need special processing of the scan data It can be seen in configuration 4 of Figure 3 1 1 1 above the LMS was programmed to scan a designated area in front of it For example an area of 5 m by 5 m can be defined and to increase the safety distance of the Cycab a bigger field can be defined The size of the field can be easily defined by sending the request telegram to the LMS Then the Obstacle Avoidance will be programmed to check for a change in the scan data received As soon as an obstacle is within the defined field boundary the program will detect a change and send a request to the MPC555 subsequently to either stop the vehicle or steer away 3 2 Car Following 3 2 1 Extraction and Processing of Data 105 For sophisticated and complicated application like Car Following it is necessary to retrieve and
40. ed driving Recharging Induction charging Table 1 1 1 1 Specifications of Cycab 55 CCD camera for remote control Joystick for manual driving Multimedia terminal Linear camera for platoon driving Infrared targets for platoon driving Ultrasonic sensors for collision avoidance Steering actuator One electric drive motor per wheel One electric brake motor per wheel Four lead acid batteries and electronic management Note The SICK LMS is now attached in front of the Cycab below the Linear Camera 56 Figure 1 1 1 1 Layout of Cycab 57 Photo 1 1 1 1 Cycab with SICK LMS at INRIA Rhone Alpes From Photo 1 1 1 1 it can be seen that the Cycab at INRIA now has a SICK LMS attached to the front centralised position 1 1 2 Mechanics and Electronics of New Cycab The mechanics is based on a small electrical golf car frame already produced in small series The use of four identical wheel motor blocks allows cost reductions by re using identical parts and volume four small engines with small power controllers are easier to build and integrate than a big one with a high power controller Consequently the architecture is modular and the vehicle is easier to drive the four 58 wheels are propulsive and directive The steering is made through an electrical jack mechanically linked to all the wheels Each wheel motor block has it s own power amplifier driven by the new Motorola MPC555 microcontro
41. ere concentrated on programming the serial interface program with numerous tests troubleshooting and debugging Finally upon the completion of the realtime serial interface implementation application programs on Car Following and Obstacle Avoidance were looked into and are currently in the process of testing and implementation This report was written to be as concise and clear as possible to the reader Please note that hexadecimal numbers are often used in this report Thus numbers like OxXX and XXH that appear in this report are all in hexadecimal format ACKNOWLEDGEMENT INRIA Rhone Alpes ACKNOWLEDGEMENT During the entire period of this Industrial Attachment a lot of help and cooperation were rendered by the fellow researchers supervisors and colleagues in my department Moyens Robotiques INRIA Rhone Alpes Therefore would like to express my sincere gratitude to all of them and especially My project supervisor Mr Gerald BAILLE Research Engineer Moyens Robotiques INRIA Rhone Alpes for his precious guidance time and help in my project and report Dr Herv MATHIEU Research Engineer Chief of Moyens Robotiques INRIA Rhone Alpes for his time and help in my project would also like to thank Mr Fabien LYDOIRE Project BIP Mr Kenneth SUNDARAJ Project SHARP and Mr Cedric PRADALIE Project SHARP for their aid in my work at one time or another LIST OF TABLES INRIA Rhone Alpes Table 1 1 1 1 Table 1
42. g Part 3 OK Message Receive Successful for i 0 i lt 10000 i d cos d C2 APPENDIX D Completed Program for Serial Interfacing MPC555 and SICK LMS SASA E RAAR eT EERE CT TER TET MED A TE TREAT ETE ET eee ee A AAN ee 2 ane SERIAL INTERFACE BETWEEN MPC555 8 SICK LMS f Filename Serial1 c PF Author Tan Pok Kiam Moyens Robotique INRIA Rhone Alpes E Created 04 2001 JE PR O RO Eee TERRA RN O UR ERE include lt math h gt define BufSize 500 define Max_Length 1000 int i res char msg Max_Length char data Max_Length unsigned char CrcL CrcH unsigned char LenL LenH unsigned int Len Crc_Create_Send PEER EER EEE EAEEREN E RARER LEASES EERE A RERERERES ERERESER ESE EAEREREREERERE EE RRE RAE RERERERE EE 1 UARTPutString To send a string of char using MPC555 UART EEES ER NEAR o CTE EE OE EE PR OS CR ANAA a a EOP Co SUCRE sj int UARTPutString int UartNb char St int Result 0 while St 0 0 amp amp Result 0 Result UARTPutChar UartNb St 0 St return Result ERRREREERESSEE RK MAH e O OR REEL TEE RO RR AK E LCDPutString To send a string of char to LCD screen of MPC555 board SARI ENEAN K MAA E A A AA int LCDPutString char St int Result 0 while St 0 0 amp amp Result 0 Result LCDPutChar St 0 St return Result A a A NRA RAR Cee OR TR RR nee El E LCDClear Clea
43. g ADR is used When the ADR is correct but the CRC checksum is incorrect a NAK will be sent Finally in the case where both ADR and CRC checksum is correct the LMS will respond with ACK Another verification method used was to obtain the return values 0 or 1 of certain functions For example in the initialisation of the UART serial interface of the MPC555 the function UARTInit will return a value O if there is no error Thus a 91 simple if verification statement in the program can help test if the UART is initialised properly These verification measures when implemented in the program will help in easing the task of troubleshooting or debugging as the user will know at which step the program encountered the error 92 2 3 6 The Makefile A makefile is like an instruction book that tells the compiler which library to look for which c program files and o object files to compile Also it indicates the name of the target files and the executable file that is to be compiled In order to download a program into the MPC555 the C program file with extension c must first be converted into a format understandable by the downloader The Makefile and some libraries provided by Robosoft contain specific functions for compiling a program to work in MPC555 The first part of the Makefile works like a normal Makefile It first compiles the c program files into o object files Then the o object files are furthur compiled
44. hown Thus basically the messages sent between the 2 devices are in 10 bit frame format With the data frame format known it can thus be specified in the initialisation of the UART interface in MPC555 Once specified the MPC555 UART interface will be able to send and capture data successfully to and from SICK LMS This will ensure that the MPC555 gets the correct data byte position 10 Bit Frames Table 2 1 2 1 Serial Frame Formats 80 2 2 MPC555 Control Board 2 2 1 UART Serial Interface Functions in C Language Robosoft had provided some C language libraries specific for the MPC555 microcontroller The libraries written for the UART serial interface were utilised in the implementation of the real time serial interface between the MPC555 and SICK LMS The figure 2 2 1 1 below lists out the main functions used in the programming Function Declaration Comments Int UARTInit int UartNb int Baud int nbit int Initialise UART serial nstop int parity int ButPtr int Bufsize interface on MPC555 Return 0 if all is ok int UARTClose int UartNb Disable UART serial interface when error is detected Int UARTGetChar int UartNb char C Return char read from target SICK LMS if any If no char is in the buffer then return Err SCCNoChar Int UARTGetWaitChar int UartNb char C int UARTPutChar int UartNb char x Input char to target Return 0 if all is ok Table 2 2 1 1 MPC555 UART Interface Functions
45. hways is the main complain by a large percentage of the population Besides air quality soil pollution with large amounts of hydrocarbons going to the sewage system in big cities also poses a problem The objective is to study new transportation modes and in particular to find ways to develop multimodality in order to find the most energy efficient way of satisfying transportation needs Another approach is to try to influence the needs in order to reduce them 1 1 3 4 More Pleasant Living Environment Space and energy are 2 resources that are scarce and very limited in almost every city Automobiles take up a lot of space in a city e g car parks roads highways and are one of the highest consumers of energy Though there is a recent trend towards car free cities not everyone is satisfied with this idea There will always be people who find driving a car more convenient than taking the public transport It is well known that public transport is most efficient in terms of space and energy but not very flexible and that the reverse is true for the private automobile Therefore the solution is to use public transport approach in places where space is limited and allow private cars in less crowded areas 65 1 2 Motorola MPC555 1 2 1 Microprocessor Description The MPC555 is a high speed 32 bit control unit that combines high performance data manipulation capabilities and a large on chip Flash memory with powerful peripheral sub
46. incorporated and provide information like the nature of the obstacle These shall be feedback to the Cycab which will make decisions based on it 4 2 Processing Time Time is a very important factor in decision making and it applies to the application programs of the Cycab as well The SICK LMS does a scan within a certain time and this time depends on the scan angle and angular resolution For example in this project where the LMS is requested do a 180 scan with an angular resolution of 0 5 the time taken to complete a scan is 26 ms However the time required increases as the angular resolution increases The overall objective of the Cycab is to have application programs that guide it safely and yet fast enough to satisfy the needs of people for public transport Thus if the response time for MPC555 to complete a task e g To avoid an oncoming obstacle is too long gt 500 ms the vehicle may not perform as predicted to avoid the obstacle 111 in time In order to curb this problem of long processing time it will be better to keep the program in MPC555 to a suitable length 4 3 Addition of a User Menu The current program done for the serial interface between MPC555 and SICK LMS is a simple one As can be read from the report the LMS has a lot of functions and each request and response corresponds to a different telegram so it will be better if a user menu with all the different requests is included in the program With this
47. into an ELF binary executable file format A function e f2sdxbin will convert the ELF binary executable file into a SynDEX binary file format bin understandable by the downloader Then the downloader function dwnbin will download the bin file into the MPC555 MPC555 will run the program upon receiving the bin file elf2sdxbin elf2sdxbin input file output file dwnbin input file SID Table 2 3 6 1 Description of Makefile Functions of MPC555 Table 2 3 6 1 gives a good description of how the command lines in the Makefile were written SID is the ID number of the MPC555 microcontroller The MPC555 93 given in this project has an ID of 4014H However the Makefile requires the user to input the SID as a decimal value so SID is actually 16404 Sample Makefile Commands Download elf2sdxbin TEST TEST bin dwnbin TEST bin 16404 Figure 2 3 6 1 Example of Makefile Commands for MPC555 Program From Figure 2 3 6 1 the sample in this case was taken from one of the test programs done during the attachment The C program that was written was TEST c and after the initial normal compilation an ELF binary executable file TEST was created This was the input file name for the command line elf2sdxbin and the name given for the output file was TEST bin After the SynDEX binary file TEST bin was created the downloader command line dwnbin was inserted with the input file name of TEST bin and subsequently the MPC5
48. it is much weaker than the emitted laser beam This also implies that the SICK LMS may not be able to detect objects of certain material very well Thus poor reflectors of light may not be well detected and do not make good targets For the Car Following application the objective is to program the SICK LMS to detect another Cycab in front so that the 2 Cycab will follow the leading one In order to have a higher intensity reflected laser beam 2 special light reflecting targets were placed behind the Cycab Then the position of the 2 reflector targets back of the Cycab can be easily detected as they will produce a very high intensity of reflected laser beam compared to the surrounding environment 3 2 3Mathematical Algorithm For the application program of Car Following the following 3 data are necessary e Angular position a of the target centre of the Cycab e Distance d of the target e Angle the relative orientation of the axis of the 2 vehicles 107 Figure 3 2 3 1 Mathematical Diagram Representation of Car Followin As illustrated in Figure 3 2 3 1 C and Co are the centres of the 2 reflector targets fixed to the back of the leading Cycab In order to obtain the 3 data a d and for the Car Following application the following equations derived from Figure 3 1 2 1 were used X1 d cosa X2 d2 COS amp y di sina y2 da sinaz de v x1 x2 y1 y2 X X X2 2 y y y2 2
49. ller This microcontroller is very well suited for motor control in automobiles and is capable of doing realtime data transfer Each wheel node controls a drive motor and a brake motor with all their associated sensors optical encoder brake torque measurement temperature etc connected An additional node is attached to the steering jack and the joystick Communications between the nodes are made through a CAN Controller Area Network serial bus It has been designed specially for automotive applications and allows safe communications in disturbed environment with a rate of up to 1Mbits s It carries messages of up to 8 bytes length with 50 per cent control and arbitration bits overload The network consists of 5 nodes and an on board PC which drives the screen and the hard disk Figure 1 1 2 1 below illustrates the overall network connections and nodes of the new Cycab in detail All the 3 MPC555 microcontroller are connected to the Linux PC on board the Cycab by the CAN network It can be seen that there are 2 MPC555 microcontroller in the network that control the low level control functions of the motor nodes in real time These control functions that 59 are programmed inside the MPC555 include PID feedback loop control programs One of the MPC555 is in charge of the front wheels and front steering while the other controls the back wheels and back steering The 3 MPC555 is connected to external sensor equipment like the
50. ng applications 1 3 6 LMI 400 The LMI Laser Measurement Interface is the universal evaluation system for the distance measurement values generated by the LMS One or more LMS can be combined and connected to the LMI to create a single system It can be flexibly controlled according to the particular application used The LMI 400 receives the data from the LMS in real time using an asynchronous serial interface so that every scan can be processed by the LMI A maximum of 4 LMS sensors can be physically connected to a LMI A LMS stand alone can be connected directly witho ut an LMI for diagnosis and requests for measured values Thus in this project there is no requirement for a LMI Figure 1 3 6 1 below illustrates the maximum configuration possible for a LMI management system 76 HOST LINUX PC Communicates with LMI via RS232 422 Receives LMS data in real time via RS422 LMI SYSTEM Communicates with host via RS232 422 LMS 1 Transmit scan data under real time conditions LMS 2 Transmit scan data under real time conditinne LMS 3 Transmit scan data under real time conditinne LMS 4 Transmit scan data under real time conditions Figure 1 3 6 1 Maximum Configuration for a LMI System 77 CHAPTER Il IMPLEMENTATION OF REAL TIME SERIAL INTERFACE In this chapter detailed description and explanation of the implementation of a reat time serial interface between MPC555 and SICK LMS will
51. ost A4 APPENDIX B Initial Set Up Test Program provided by Robosoft PRESSE ERASE EAR a ALAR EERE LEAS REAR LEELA DERE SEAL MARAIS IK SEAS NER ERE LEAS OO I KA ay Test C Test de l ensemble TPU PWM etc Y channel number to test 0 3 the procedure will measure an average on Y the channel Set with nMoy is ae NT NAN TE o e RA OR OP OES Be A A IE A ESAE UE PI ACI AE Y a hy WIPES SE OA Sy OLS ETE el Version 1 00 22 10 1999 FF ES LA AT A O E SONS PE ER to A OSE 14 27 005000 PIII LIED 0200 IN SCTE Di EIN AN AN Pt void InterruptHandlerCANO void void InterruptHandlerCAN1 void void InterruptHandlerSPI void void InterruptHandler2 void void InterruptHandler6 void void InterruptHandler7 void void InterruptHandlerPIT void Blink the LED as SetLED will return the previous LED state SetLED SetLED 0 E A Y A le AE A A NAZ E re E A E E E a t EN DELA E Nt Stn En La F Interrupt handler reserved for EXTERNAL IRQ lines JA AAA AAA AAA AAA A RA AA void InterruptHandler RQO void B1 void InterruptHandler RQ1 void void InterruptHandlerlRQ2 void void InterruptHandlerlRQ3 void void InterruptHandlerIRQ4 void void InterruptHandlerlRQ5 void void InterruptHandlerlRQ6 void void InterruptHandlerlRQ7 void UART Routine To put a string of char via UART
52. r Change in Operating Mode with Response Request for Change in Operating Mode without Response Request for Scan Values continuous Initialisation Flow of Main Program Capturing of Scan Values in Main Program Possible Configurations of LMS Scanning Field 48 Extraction and Processing of Data Mathematical Diagram Representation of Car Following vii 16 17 21 22 23 37 38 39 40 40 42 43 50 51 Photo 1 1 1 1 Photo 1 2 4 1 Photo 1 3 1 1 Photo 2 2 2 1 Photo 2 2 2 2 Photo 2 2 2 3 LIST OF PHOTOS Cycab with SICK LMS at INRIA Rhone Alpes MPC555 Control Board provided by Robosoft LMS 291 S05 MPC555 Control Board with Connections Top 26 MPC555 Control Board with Connections Front SICK LMS with Connections Top 53 13 15 27 28 CHAPTER INTRODUCTION TO HARDWARE In this first chapter a brief introduction on the main hardware Cycab MPC555 and SICK LMS used in the project will be given This will enable the reader to have a clear and basic understanding of the hardware before embarking on the next chapter where the main program is explained in detail 1 1 Cycab 1 1 1 System Description and Specifications The Cycab is a small intelligent vehicle that runs on electricity It had been designed to transport up to two persons in downtown areas pedestrian malls large industrial or amusement parks and airports at a maximum speed of 30 km h It offers two new fun
53. r LCDScreen Modification Required JARRETT AIETEN EEE EERE O N LATA SRLS EE Le Nene OE te D1 gi void LCDClear char c 0 while c 4 UARTGetWaitChar 1 amp c UARTPutChar 1 c LCDInit LCDPutString LCDInit A E ATER ES ARER ORES SICKCreateCRC Create CRC16 CHECKSUM for response msg from LMS FREER EES SRS ETAT TEES AREEAE EFE MIAL HH E RINI RARER POSS gt A AAA R EEE define CRC16_GEN_POL 0x8005 define MKSHORT a b unsigned short a unsigned short b lt lt 8 unsigned short SICKCreateCRC unsigned char CommData unsigned int uLen unsigned short uCrc16 unsigned char abData 2 uCrc16 0 abData 0 0 while uLen abData 1 abData 0 abData 0 CommData if uCrc16 amp 0x8000 uCrc16 uCrc16 8 0x7fff lt lt 1 uCrc16 CRC16 GEN POL else uCrc16 lt lt 1 uCrc16 MKSHORT abData 0 abData 1 return uCrc16 SS ES TE Stee Pe PCE ETERS TT PTO RP oe ee lt SICK_CRC_Check CRC checking function for responses from SICK i EERE REESE EERE EERE EEE ET Ee E eee RARE RR int SICK_CRC_Check unsigned int Crc_Create Crc_Recvd Crc_Create SICKCreateCRC amp msg 0 Len 4 Create CRC for msg from STX Status Crc_Recvd CrcL CrcH 256 if Crc_Recvd Crc Create LCDPutString CRC_Check Correct LCDClear return 0 D2 else LCDPutString CRC_Check ERROR
54. re of full duplex type Full duplex devices can transmit and receive data at the same time The maximum data speed for a RS232 is about 115 Kbauds while the RS422 can go up to about 10 Mbauds The RS232 RS422 serial interface used has a Sub D 9 pin connector and this is commonly used in interfacing between computer peripherals Figure 2 1 1 1 shows the front view of a typical Sub D 9 pin connector that was used Figure 2 1 1 1 Sub D 9 Pin Connector View 2 1 2 Serial Format Before commencing with the programming of the real time serial interface implementation the serial format of the data message frames that MPC555 and SICK LMS will send receive must be known As the 2 hardware are from 2 entirely different manufacturers there will always be the possibility of hardware incompatibility problems It is very important that both the receiving and transmitting devices use the same data frame format With the same data frame format defined 79 then both hardware can capture and send data successfully based on the defined format All data frames must have a start bit and at least one stop bit The SCI Serial Communication Interface in MPC555 provides hardware support for both 10 bit and 11 bit frames In the case of message frames sent by the SICK LMS a byte of data consists of 1 start bit 8 data bits 0 parity bit and 1 stop bit With reference to Table 2 1 2 1 below the different data frame formats that MPC555 can support is s
55. reciated good documentation will be very useful to fellow researchers working on follow up projects Working as a junior researcher also allowed me to experience the working environment of a researcher Everyone in the same project group contributes to the final goal of the project For example the Cycab is quite a big project that involves many researchers From the mechanics and electronics of the vehicle linear camera guiding to the serial interfacing of the SICK LMS all these contributions are all made by different researchers with the same final aim Therefore teamwork is very important in research Finally this report was written to be as clear and concise as possible with the aim of serving as a guide to anyone who will be working on similar or follow up projects 57 APPENDIX A INRIA Rhone Alpes REFERENCES Cycab 1 2 3 INRIA Homepage http www inria fr INRIA Rhone Alpes Homepage http www inrialpes fr Project LARA Cycab Web page http www lara inria fr cycaba MPC555 4 5 6 Motorola Homepage http e www motorola com Motorola MPC555 User Manual Motorola MPC555 Evaluation Board Quick Reference SICK LMS 7 8 9 10 11 SICK Homepage http www sick fr SICK LMS LMI 400 Definition of telegrams between the user interface and LMS or LMI systems via RS 422 RS 232 SICK User software LMS LMI Laser Measurement System
56. red in this way are put together to form a model of the surrounding area s contours Using the serial interface of the unit measurements are transferred in real time or other specified rates to a host PC for further evaluation Emitter Receiver Rotating mirror Figure 1 3 2 1 Operating Principle of SICK LMS 72 100 scan 180 scan Figure 1 3 2 2 Scan Angle and Angular Resolution As seen from Figure 1 3 2 2 the LMS does a planar scan of either 100 or 180 with an angular resolution choice of 0 25 0 5 or 1 This implies that for a 180 scan with 0 5 angular resolution there will be a total of 361 scan values 180x2 1 0 value 361 Each scan value consists of 2 bytes of data and all these are important as the LMS will send the number of data bytes according to the request 73 1 3 3 Specifications LMS 291 S05 Dimensions WxHxD 155x210x156 mm Hi see Range without supplementary Up to 30 m reflectors Range with minimum reflectivity 1 8 Angular resolution 100 Scan 0 25 0 5 1 No Of Scan Values 401 201 101 180 Scan 0 5 1 No Of Scan Values 361 181 Configuration by software Response times 52 ms with angular resolution of 0 25 26 ms with angular resolution of 0 5 13 ms with angular resolution of 1 0 cin Table 1 3 3 1 Specifications of SICK LMS 291 S05 74 1 3 4 Features e High resolution measurement system e Non contact optical measu
57. rement over long distances e High scanning frequency allows high speed movement of objects e An active system requiring no illumination of the target area e No reflectors or markings necessary on target objects e Background and supporting medium have no affect on measurements e Any orientation of target objects is possible e Transfer of measurement data in real time available for further processing or control functions e Self testing no external testing procedures required e Suitable for outdoor use 1 3 5 Possible Applications for SICK LMS The LMS can be used for standard applications involving measurement of objects and position determination monitoring areas and vehicle guidance and collision control The fundamental ability of laser scanners to offer accurate contour measurement is a very important asset for use in the above applications Advanced laser technology is relatively straightforward to acquire install and maintain It can provide the precision which adds substantial value to the container handling process Collision control is a problem in many areas for example in the container handling terminal The laser scanner s function is to monitor one or more zones in front of the 75 fixed path or mobile equipment and to alert an operator of a potential collision i e it functions as a system designed to avoid collision This function can be extended to many other areas like car parking guiding and car followi
58. systems This MCU Micro Controller Unit is built up from standard modules that interface through a common intermodule bus IMB The MPC555 incorporates a PowerPC Core with a Floating Point Unit a 26 Kbytes fast RAM a 6 Kbytes dual ported RAM for TPU microcode RAM DPTRAM 448 Kbytes flash EEPROM with 5 volt programming a 5 volt I O system a System Interface Unit USIU a Queued Serial Multi Channel Module ASMCM dual CAN 2 0B controller modules TouCANTM dual Time Processor Units TPU3 a Modular I O System MIOS1 and dual Queued Analogue to Digital Converters QADC64 It operates at 40 MHz with dual supply of 3 3 V for Core 5 V for FLASH 1 2 2 Features e RISC MCU Central Processing Unit RCPU e Four Bank Memory Controller e U Bus System Interface Unit USIU e Flexible Memory Protection Unit e 448 Kbytes of CDR MoneT Flash EEPROM Memory CMF e 26 Kbytes of Static RAM e GeneraltPurpose I O Support e Two Time Processor Units TPU3 e 18 Channel Modular I O System MIOS1 66 e Two Queued Analogue to Digital Converter Modules QADC e Two CAN 2 0B Controller Modules TouCANs e Queued Serial Multi Channel Module ASMCM Though the MPC555 has a lot of useful features not all were used in this project The 2 main features that are of special interest to the project are the TouCANs and QSMCM modules highlighted above 1 2 3 Queued Serial Multi Channel Module QSMCM The Queued Serial Multi Channel Modul
59. t of the SICK LMS 84 2 3 SICK LMS 2 3 1 LMS Telegram Structure The SICK LMS requires pre defined telegrams for communication with the Host which can either be a computer or in this case a microcontroller MPC555 Data is transferred in binary format but written and displayed in hexadecimal format and transfer is initiated by the STX byte start of text O2H In addition the transferred data is also in INTEL data format This implies that word transfer takes place with the lower address and the least significant byte first followed by the bytes of higher address and significance The structure of the telegrams sent and received must comply with the pre defined telegram structure throughout the entire program Otherwise errors will occur and make troubleshooting difficult Table 2 3 1 1 below shows a typical LMS telegram structure and Table 2 3 1 2 describes the structure in detail N bytes Status Table 2 3 1 1 LMS Telegram Structure 85 Designation Data width Description ORNE Address 22 the LMS to be contacted Note The LMS adds the value 80H to the address when responding to the Host Computer Number of data bytes CMD Data Status CMD Command byte sent to the LMS When responding LMS will send the original command byte with the addition of 80H to the value pae ee Optional depends on the previous command Optional the LMS transmits the status message only when it is sending out data When sen
60. urn value is a 0 it means that the UART was initialised properly From the program the function declaration is UARTInit 0 19200 8 1 0 amp Buffer BufSize In sequence 0 refers to the serial COM 1 port number of the MPC555 control board 19200 refers to the desired baud rate 8 is the number of data bits 1 is the number of stop bit and finally 0 is the number of parity bits amp Buffer is the pointer to the declared buffer while BufSize is the size of the buffer which had been declared to be 128 bytes in the beginning of the program After the UART was initialised the program continues to the next step of sending a command string SICKInit to the LMS This is to initialise the LMS with specifications corresponding to that of the MPC555 UART serial interface With reference to the program the LMS telegram structure Table 2 3 1 2 and the LMS telegram list the initialisation telegram SICKInit can be interpreted However the array init 16 was declared with a size of 16 bytes but only 14 bytes were included The reason is the last 2 bytes are reserved for the CRC bytes and they are created by the function SICKCreateCRC The block of data from the 1 byte to the 14 byte are included in the SICKCreateCRC calculation After that the CRC Low byte is put into init 14 and CRC High byte into init 15 This is because data is transferred in INTEL data format for SICK LMS 101 The next step in the program is the function SICKChkACK where

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