CXM543 User`s Manual - Willow Technologies
Contents
1. eere 12 8 Appendix B CXM543 Commands and 13 8 1 CXM543 Commands eret rotae cerra ponere sn 13 8 2 CXM543 Data Transmission Modes sese 14 8 3 Checksum Calculation sese 18 84 BBROM Map xionebneeeite misti ice Eo e Re ee LER eiee 20 8 5 Software Data Correction Equations eee 22 9 Appendix C Hard Iron Correction for CXM543 23 9 1 Pescapton kssansgepomssmskll bodbsasdtlin 23 9 2 Setup Procedure 2 tH dte insektet 23 9 3 Determining the Hard Iron Offset sss 24 9 4 Hard Iron Calibration Commands esee 25 9 5 Three dimensional Correction sss 26 9 6 Two dimensional Correction esee 27 Doc 7430 0115 01 Rev A Pagei Crossb w CXM543 User s Manual 9 7 10 11 11 1 11 2 11 3 11 4 Caveats D 28 Appendix D Filter Values and Data Rates 29 Appendix E Warranty and Support Information 30 CUStOMEr Service I 30 Contact Directory sereen a ao teara EE ESEE EER AE Eaa 30 Return Procedure ai uiae eter edet e pete reo dave 30 Watranty usa cia eke keen 31 Page ii Doc 7430 0115 01 Rev A CXM543 User s Manual Crossb w About this Manual The following annotations have been used to provide additional information 4 NOTE Note provides additional information about the topic2. M EXAMPLE Examples are given throughout the manual to help the reader understand the terminology IMPORTANT This symbol defines items that have significant meaning to the user 6 WARNING The user should pay particular attention to this symbol It means there is a chance that physical harm could happen to either the person or the equipment The following paragraph heading formatting is used in this manual 1 Heading 1 1 1 Heading 2 1 1 1 Heading 3 Normal Doc 7430 0115 01 Rev A Page iii CXM543 User s Manual Crossb w 1 Introduction 1 1 Description of the System The CXM543 is a high speed digital output orientation measuring system It can transmit the orientation angles roll pitch and azimuth of a body to which it is mounted at a rate of 25 samples second The basic accuracy of the CXM543 is 0 5 Data transmissions are made over a bi directional serial port using either RS 232 or TTL levels The baud rate and sampling rate are user programmable The CXM543 measures orientation by employing a 3 axes accelerometer to measure roll and pitch and a three axis magnetometer to determine azimuth The CXM543 can be configured to run in two modes viz Vector and Angle In vector mode the unit transmits the accelerometer and magnetometer sensor outputs and transmission speeds up to 250 samples sec are possible In angle mode the CXM543 transmits the system roll pitch and azimuth angles The CXM543 can be used
3. North Azimuth N Figure 3 CXM543 Azimuth Definition Doc 7430 0115 01 Rev A Page 11 Crossb w CXM543 User s Manual 7 Appendix A Mechanical Specifications 7 1 CXM543 Outline Drawing 6 x 0 125 Page 12 Doc 7430 0115 01 Rev A CXM543 User s Manual Crossb w 8 Appendix B CXM543 Commands and 8 1 CXM543 Commands All Commands must be followed by a return All changes to the mode value are saved as the power up mode M Send the current mode value M R All data is sent as raw A D Counts in ASCII four digit hex values or binary values depending on the current mode M C All data is sent as Gammas formatted as Base Ten fixed point text or binary values depending on the current mode M B _ Set data is formatted as binary numbers MzT _ Set data is formatted as text numbers M E Send a checksum with all data MzN Don t send a checksum M A Send corrected data as angles rather than vectors M V Send data as vectors rather than angles A Start Auto Send Data S Stop Auto Send D Send the current calibrated data value in a floating point format DR Send the current raw data value in a hex format L Unlock calibration mode O Calibration zero all the sensors XM Calibration 1 2 Gauss X field applied YM Calibration 1 2 Gauss Y field applied ZM Calibration 1 2 Gauss Z field applied QM Calibration 1 2 Gauss applied field delta XA Calibrate 1G applied gravitation field YA Calibrate 1G
4. 1E 1F Soft bow correction X 20 21 Soft bow correction Y 22 23 Soft bow correction Z 24 25 Soft offset X magnetometer 26 27 Soft offset Y magnetometer 28 29 Soft offset Z magnetometer 2A 2B Soft scale X magnetometer 2C 2D Soft scale Y magnetometer 2E 2F Soft scale Z magnetometer 30 31 Soft ortho XY magnetometer 32 33 Soft ortho XZ magnetometer 34 35 Soft ortho YX magnetometer 36 37 Soft ortho YZ magnetometer 38 39 Soft ortho ZX magnetometer 3A 3B Soft ortho ZY magnetometer 3C 3D Pacing value Accelerometer A D Configuration Settings 3E 40 A D offset calibration 0 set when the A D is calibrated 41 43 A D gain calibration 0 set when the A D is calibrated 44 46 A D offset calibration 1 set when the A D is calibrated 47 49 A D gain calibration set when the A D is calibrated 4A AC A D offset calibration 2 set when the A D is calibrated 4D 4F A D gain calibration 2 set when the A D is calibrated Magnetometer A D Configuration Settings 50 52 A D offset calibration 0 set when the A D is calibrated 53 55 A D gain calibration 0 set when the A D is calibrated 56 58 A D offset calibration 1 set when the A D is calibrated 59 5B A D gain calibration 1 set when the A D is calibrated 5C 5E A D offset calibration 2 set when the A D is calibrated Doc 7430 0115 01 Rev A Page 21 Crossb w CXM543 User s Manual 5F 61 A D gain calibration 2 set when the A D is calibrated 62 63 Filter Settings Set for Data Rate vs Data Noise 01 FAST mode ena
5. 689 The checksum is 89 which is the least significant byte of the sum When the CXM543 mode is selected to be raw the transmitted data represents the raw Analog to Digital A to D count outputs for the various magnetometer and accelerometer sensors The A to D s have 16 bit resolution and hence their output ranges in decimal from 32 768 to 32 767 In hex the A to D outputs range is provided in Table 3 Table 3 CXM543 A to D Output Range Count Hex Output 32767 7FFF 0 0000 1 FFFF 32768 8000 Page 16 Doc 7430 0115 01 Rev A CXM543 User s Manual Crossb w If the selection M R is made then the mode can be further specified by selecting three sub modes M h hex mode M b binary mode M i integer mode Note that the above commands can be given individually or as a single combination of commands For instance to put the CXM543 in raw binary mode M r lt CR gt M b lt CR gt where lt CR gt is a carriage return could be issued or the command M rb lt CR gt could be issued In hex mode the CXM543 will transmit ASCII hex numbers in the following format MX MY MZ AX AY AZ T K lt CR gt lt LF gt MX represents the X magnetometer A to D output and is of the form HHHH where each H is an ASCII character represents a hex digit ranging from 0 to F The magnetometer and accelerometer outputs all have this same form T represents a hex number of the same form i e HHH
6. 1 2 3 4 5 104 decimal The number 104 decimal is 68 in hex this is the transmitted checksum Consider a second example consisting of corrected angle data in decimal forms mode cad Roll Pitch Azimuth Total A Total M CS lt CR gt lt LF gt 100 71 90 05 1 12 1 00000 0 49543 53 The checksum is calculated as follows 1 7 1 9 5 1 1 2 1 4 9 5 4 3 53 decimal The number 53 decimal is 35 hex and this is the checksum To calculate the checksum for binary transmissions the data bytes are summed and the checksum is the least significant byte of the sum For instance consider a transmission of raw vector data in binary format mode rub AX AY AZ MX MY MZ CS EOT 123456789A9876543221FEBCIDSA The checksum is calculated as follows 12 34 56 78 9A 98 76 54 32 21 FE BC 51D The least significant byte of this summation is ID and this is the transmitted checksum For a binary transmission of corrected angular data mode cab as follows Roll Pitch Azimuth Tot A Tot M CS EOT 23F165A3521312345678955A The checksum is calculated as follows 23 F1 65 A3 52 13 12 34 56 78 395 therefore the checksum is 95 Doc 7430 0115 01 Rev A Page 19 Crossb w CXM543 User s Manual 8 4 EEROM Map For all EEROM constants the least significant byte is stored in the lowest address and the most the most significant byte is stored in the highest address 00 Not Used 01 CPU Clock Speed Divisor 1 7 Clock Divisor 8 O Run at full clock speed
7. Crossbow Technology customer you have access to product support services which include e Single point return service e Web based support service e Same day troubleshooting assistance e Worldwide Crossbow representation e Onsite and factory training available e Preventative maintenance and repair programs e Installation assistance available 11 2 Contact Directory United States Phone 1 408 965 3300 8 AM to 5 PM PST Fax 1 408 324 4840 24 hours Email techsupport xbow com Non U S referto website www xbow com 11 3 Return Procedure 113 1 Authorization Before returning any equipment please contact Crossbow to obtain a Returned Material Authorization number RMA Be ready to provide the following information when requesting a RMA e Name e Address e Telephone Fax Email e Equipment Model Number e Equipment Serial Number e Installation Date e Failure Date e Fault Description Page 30 Doc 7430 0115 01 Rev A CXM543 User s Manual Crossb w 11 3 2 Identification and Protection If the equipment is to be shipped to Crossbow for service or repair please attach a tag TO THE EQUIPMENT as well as the shipping container s identifying the owner Also indicate the service or repair required the problems encountered and other information considered valuable to the service facility such as the list of information provided to request the RMA number Place the equipment in the original shipping container s
8. in either a command mode or autosend mode In the command mode the CXM543 responds to commands to transmit data issued by an external computer In autosend mode the CXM543 commences sending data as soon as power is applied to the unit 1 2 Package Contents In addition to your CXM543 sensor product you should have e 1 CD with MagView Software Mag View will allow you to immediately view the outputs of the Sensor on a PC running Microsoft Windows e 1 Digital Signal Cable This links the Sensor directly to a serial port Only the transmit receive power and ground channels are used e 1 User s Manual This contains helpful hints on programming installation valuable digital interface information including data packet formats and conversion factors Doc 7430 0115 01 Rev A Page 1 Crossb w CXM543 User s Manual 2 Electrical and Mechanical Interface The CXM543 is powered from a single input voltage that can range between 7 5 V and 15 V Current consumption is 100 mA Two serial interfaces are available one that uses RS 232 levels and one that uses TTL levels The baud rate is user programmable and can be set at the following values 300 1200 2400 4800 9600 19200 38400 and 72800 The data words employ 8 bits with one stop bit and no parity A female 9 pin D connector is used to provide an electrical interface to the CXM543 system The Pin out of this connector is shown in Table 1 Table 1 CXM543 Connector Pin O
9. making sure there is adequate packing around all sides of the equipment If the original shipping containers were discarded use heavy boxes with adequate padding and protection 11 3 3 Sealing the Container Seal the shipping container s with heavy tape or metal bands strong enough to handle the weight of the equipment and the container 1L34 Marking Please write the words FRAGILE DELICATE INSTRUMENT in several places on the outside of the shipping container s In all correspondence please refer to the equipment by the model number the serial number and the RMA number 11 3 5 Return Shipping Address Use the following address for all returned products Crossbow Technology Inc 4145 N First Street San Jose CA 95134 Attn RMA Number XXXXXX 11 4 Warranty The Crossbow product warranty is one year from date of shipment Doc 7430 0115 01 Rev A Page 31 Crossb w Crossbow Technology Inc 4145N First Street San Jose CA 95134 Phone 408 965 3300 Fax 408 324 4840 Email info xbow com Website www xbow com
10. out on the PC serial port The power supply positive should be connected to V 7 5 to 15 Volts The TTL serial lines and the configure line can be left unconnected but not grounded In particular do not ground the configure pin pin 8 during the hard iron correction Grounding this pin will set the CXM543 to Config mode When the PC is connected and running a terminal emulator program the string APS 543 V1 162 should be displayed If the CXM543 follows this with a stream of data then type s and a carriage return to take it out of autosend mode The CXM543 can be checked out using the procedure described in Section 4 2 9 3 Determining the Hard Iron Offset Once the CXM543 is connected communicating and in Run mode one can determine the hard iron correction The hard iron offset can only be determined with the CXM543 rigidly mounted to a platform and the entire platform must be moved during the correction procedure as will be described The hard iron correction which uses this offset can be turned on or off The CXM543 is described in the following text as having x y and z axis These are a set of approximately orthogonal directions described by the label on the top of the sensor One might think of these as the forward direction the sideways direction and the up direction for the platform Page 24 Doc 7430 0115 01 Rev A CXM543 User s Manual Crossb w The left side is the left side of an imaginary pilot
11. to prevent magnetic field errors which will reduce the accuracy of the azimuth reading The roll and pitch readings are not affected by the magnetic field present so a flat level surface even if it is magnetic can be used to check roll and pitch Place the CXM543 on a level surface with the mounting flange down Rotate the system so that the connector is pointed North use a compass to accomplish this Issue the following commands to the CXM543 M T lt CR gt M A CR where lt CR gt is a carriage return These commands put the CXM543 in text as opposed to binary mode and angle as opposed to vector mode Set the transmission speed to a slow value about once per sec by issuing the command F1 CR Next put the CXM543 in autosend data mode by issuing the command A CR The CXM543 will commence to send data in the format Roll Pitch lt Azimuth gt Total gravity field Total magnetic field Doc 7430 0115 01 Rev A Page 5 Crossb w CXM543 User s Manual Verify that the roll angle is near 0 pitch is near 90 and azimuth is near 0 Verify that the total gravity field is near 1 00 and the total magnetic field is between 0 4 and 6 The magnetic field amplitude in Gauss varies around the world between these values Next orient the CXM543 in various different known orientations and check the accuracy of the measured data Stop the data transmission and change to sensor vector output mode b
12. 1 Enable clock division CPU Speed 4 9152Mhz 129 ClockDivisor This allows the use of lower UART baud rates and lower power consumption For example 300 baud could be used with the Clock Divisor set to 125 to divide the clock rate by 4 and the baud rate control register set to 255 02 Operating Mode 1 Send corrected data 2 Autosend data until stop autosend command received 3 Send data only once on power up or single data by command 4 Send data in a text format 5 Send data in a decimal format only checked if in text format 6 Calibration mode uses this bit 7 Send check sum with data 8 Send angles 03 More Operating Mode 1 Send Check Sum with Data 2 Not used 3 Not used 4 Not used 5 Not used 6 Not used 7 Not used 8 Not used 04 Baud Rate Control BaudRate 4 9152Mhz 16 BaudRateControl 1 Values for common baud rates with no clock dividing 1200 255 FFH 19200 31 1FH 2400 127 7FH 38400 7 7H 9600 63 3FH 76800 3 3H 05 Not used Page 20 Doc 7430 0115 01 Rev A CXM543 User s Manual Crossb w 06 07 Soft offset X accelerometer 08 09 Soft offset Y accelerometer OA OB Soft offset Z accelerometer OC OD Soft scale X accelerometer OE OF Soft scale Y accelerometer 10 11 Soft scale Z accelerometer 12 13 Soft ortho XY accelerometer 14 15 Soft ortho XZ accelerometer 16 17 Soft ortho YX accelerometer 18 19 Soft ortho YZ accelerometer 1A 1B Soft ortho ZX accelerometer 1C 1D Soft ortho ZY accelerometer
13. CXM543 User s ely Revision A March 2005 Document 7430 01 15 01 Crossb w Crossbow Technology Inc 4145 N First Street San Jose CA 95134 Tel 408 965 3300 Fax 408 324 4840 email info xbow com website www xbow com 1999 2005 Crossbow Technology Inc All rights reserved Information in this document is subject to change without notice Crossbow and SoftSensor are registered trademarks and DMU is a trademark of Crossbow Technology Inc Other product and trade names are trademarks or registered trademarks of their respective holders CXM543 User s Manual Crossb w Table of Contents IE nilo e 1 1 1 Description of the System sse 1 1 2 Package Contents ite eee ebrei p rd 1 2 Electrical and Mechanical Interface esses 2 3 Quick Siaki oinin niinen ier Ea iisi 3 3 1 Mag View Software sess eene eene 3 3 2 iS oes M 3 3 3 Setup Mas VieW T K ees 4 3 4 Take Measurements ien eee tes ceti nanne eE e ERE REPE AE E 4 4 Terminal Emulator and Checkout eese 5 4 1 Startup Using a Terminal Emulator Program 5 4 2 Kyrie m R 5 CXM543 Configuration and Data Formats 7 6 Description of the CXM543 Orientation Angles 10 7 Appendix A Mechanical Specifications 12 7 1 CXM543 Outline Drawing
14. H and corresponds to the system temperature To obtain the temperature in C divide the hex digits by 128 K represents the system checksum and is a hex number of the form HH To obtain the checksum all of the data bytes in the transmission are added The checksum is the least significant 8 bits or 2 hex digits of this summation The lt CR gt and lt LF gt in the transmission represent ASCII characters for carriage return 0D Hex and line feed 0A Hex Note that the ASCH space character Hex 20 is transmitted after each sensor output is transmitted In raw binary mode M rb the data transmissions are much more compact The transmissions are of the form AXAYAZMXMYMZTK where AX represents the X accelerometer output etc T represents the temperature and K represents the checksum AX consists of two bytes Doc 7430 0115 01 Rev A Page 17 Crossb w CXM543 User s Manual The most significant byte is transmitted first The most significant bit of this byte is also transmitted first Decoding of the binary data is in accordance with the Table 4 below Table 4 Decoding CXM543 Binary Data Count Hex Output 32767 0111 1111 1111 1111 0 0000 0000 0000 0000 1 1111 1111 1111 1111 32768 1000 0000 0000 0000 T is a byte number representing the system temperature in C and K is a one byte checksum obtained by taking the least significant 8 bits resulting from adding all of the data bytes In binary mode
15. a typical transmitted value is 0 28265 G T is the system temperature in degrees C and is of the form TT T K is a one byte checksum calculated by summing all of the digits in the transmitted data ignoring signs and decimal points For instance if the transmitted data is AX AY AZ MX MY MZ T S lt CR gt lt LF gt 0 00128 0 03076 0 98512 0 02282 0 25378 0 34216 32 0 70 The checksum is 70 as indicated since 1 2 8 3 7 6 9 8 5 1 2 2 2 8 2 2 5 3 7 8 3 4 2 1 6 3 2 1 112 decimal or 70 hex Note that the inclusion of the temperature and a checksum in the transmitted data output is optional To enable the sending of these data issue the commands M TO Doc 7430 0115 01 Rev A Page 15 Crossb w CXM543 User s Manual M KO To disable the sending of these data issue the commands M TN M KN If corrected data in angle and decimal mode is selected Mode cad the data output format is as follows Roll Pitch Azimuth Total M Total A CS lt CR gt lt LF gt 21 73 90 05 180 01 0 45671 1 00000 3D For corrected data in vector data in binary mode Mode cvb a typical transmission is as follows AX AY AZ MX MY MZ T CSEOT FFEB 01F8 3FOC 02EC 7CEA 2BCC 1000 89 5A This binary transmission is equivalent to the corrected decimal vector previously shown above namely AX AY AZ MX MY MZ T 0 00128 0 03076 0 98512 0 02282 0 25378 0 34216 32 0 The binary checksum is computed as follows FF EB 01 F8 3F 0C 02 EC 7C EA 2B CC 10 00
16. applied gravitation field ZA Calibrate 1G applied gravitation field QA Calibrate 1G applied gravitation field delta F Set the filter value for the A Ds F Display the filter value for the A Ds Doc 7430 0115 01 Rev A Page 13 Crossb w CXM543 User s Manual FH Quick set filter value can be 1 9 with 1 giving the slowest and most accurate data and 9 giving the fastest and least accurate data B Send the run mode baud rate B Set run mode baud rate 300 76800 baud is accepted In Config Mode the baud rate is always 9600 P Display the current pacing value P HHHR Set a pacing value to slow the data rate E Send all EEROM data EfHHHt Send EEROM data followed by 4 hex digits address and optional 2 digits representing the number of bytes to send WIHHEXX Write EEROM data followed by a 4 hex digit address and 2 hex digits of data C Reset and calibrate A D s I Send ID and many internal values i Reset and restart sensor Display help 8 2 CXM543 Data Transmission Modes At the top level the CXM543 can be put in either raw M r or corrected M c mode Raw mode is seldom used after a CKM543 system has been factory calibrated This mode is used mainly to enable direct access to the system analog to digital A to D converters for troubleshooting When the CXM543 mode is selected to be corrected the magnetometer and accelerometer outputs are corrected for scale offset and alignment factors When t
17. bled 02 Skip mode enabled 03 Chop mode enabled 04 Must be 0 05 16 12 bit sync filter 8 5 Software Data Correction Equations Xout Xin XOffset XScale 32768 Yin YOffset YScale 32768 YOrtho 4 Zin ZOffset ZScale 32768 ZOrtho 65536 Yout Yin YOffset YScale 32768 Xin XOffset XScale 32768 XOrtho Zin ZOffset ZScale 32768 ZOrtho 65536 Zout Zin ZOffset ZScale 32768 Xin XOffset XScale 32768 XOrtho 4 Yin YOffset YScale 32768 YOrtho 65536 Page 22 Doc 7430 0115 01 Rev A CXM543 User s Manual Crossb w 9 Appendix C Hard I ron Correction for CXM543 9 1 Description A hard iron offset refers to the perturbation of magnetic field experienced by an orientation sensor caused by nearby magnetic materials which are on the same platform as the sensor i e a constant offset in the magnetic field in the frame of the sensor This perturbation could be measured directly by placing the sensor and platform in a magnetically shielded enclosure but this is often not practical The CXM543 sensor has the capability to measure the hard iron offset by placing the sensor and platform at a set of different orientations and collecting data at each orientation Once measured the hard iron offset can be subtracted from the magnetometer readings thus enabling a more accurate measurement of orientation The set of orientations used for
18. enu 5 The Monitor window allows the user to view the data being sent from the sensor and allows the operator to send commands to the sensor 3 4 Take Measurements Once you have configured MagView to work with your sensor pick what kind of measurement you wish to see AutoData will show you the output you choose as a strip chart type graph of value vs time DataOnce issues the command to send the data one time Monitor window allows the user to view the data being sent from the sensor and allows the operator to send commands to the sensor Page4 Doc 7430 0115 01 Rev A CXM543 User s Manual Crossb w 4 Terminal Emulator and Checkout 4 1 Startup Using a Terminal Emulator Program Connect the CXM543 to serial port of a PC as described in Section 3 2 Connect a power supply 47 5 V to 15 V to the red positive and black banana plug on the cable Start up a terminal emulator program on the PC e g Windows HyperTerminal PC Plus etc Configure the terminal emulator program for direct connect to an available COM port and select the baud rate 9600 with one stop bit and no parity Apply power to the system and check to see that the unit transmits a start up message APS 543 V1 12 4 2 System Checkout After the CXM543 is operational and communicating with a computer its proper operation can be checked out by placing it on a flat level non magnetic surface The non magnetic nature of the surface is necessary
19. f the platform cannot be turned upside down then only the 2 dimensional hard iron correction will be possible The CXM543 must be connected to a terminal emulator program on a PC to perform the correction The Section 4 1 explains the procedure for Doc 7430 0115 01 Rev A Page 23 Crossb w CXM543 User s Manual setting the CXM543 up with a terminal emulator program The CXM543 must be in run mode to do the hard iron correction For this you will need the CXM543 a PC with a terminal emulator program a power supply capable of delivering 7 5 to 15 volts and cables The CXM543 and the terminal emulator must both be set to the same baud rate usually 9600 If the CXM543 baud rate is unknown or cannot be used you may need to temporarily set the CXM543 to Config mode In Config mode the sensor is always at 9600 baud The Run mode baud rate can be set only when the sensor is in Config mode If a 543 Breakout Box is available then set up the sensor as described in section 4 1 of the manual The mode switch on the box should be in Run not Auto or Config If a connection box is not available then the sensor will have to be connected by means of homemade wiring Chapter 3 provides the pin out of the sensor The ground should be connected to the computer ground and the negative side of the power supply RS 232 out from the CXM543 should be connected to RS 232 in on the PC serial port while RS 232 in should be connected to RS 232
20. facing forward and sitting with his head up Left and right side do not refer to the left and right of the operator 9 4 Hard Iron Calibration Commands The hard iron correction procedures are described in the following sections The commands that are used with the 543 to complete the procedure are described as follows Lists all commands recognized by the sensor both those related to hard iron corrections and those not related to hard iron HI The hard iron correction is toggled on or off if a correction is available H2 2 dimensional data is to be collected with the CXM543 prompting the user with a set of good orientations These orientations do not need to be precisely met If some data points have already been gathered then this data is lost and the process starts all over H2 uses 4 data points H3 3 dimensional data is to be collected with the CXM543 prompting the user as with H2 For H3 6 data points are used HP Records a hard iron data point using the present orientation If an H2 or H3 is being used to prompt the data then the correction will be calculated when the proper number of points have been gathered If neither H2 nor H3 has been used then data will be gathered until the HC command is used or the gathering of data is aborted by means of the HQ command or restarted by means of the H2 or H3 commands HC Calculates a hard iron correction using the data gathered so far The hard iron correction continues to be a
21. h obtaining an accurate correction This is often referred to as a soft iron perturbation Page 28 Doc 7430 0115 01 Rev A CXM543 User s Manual Crossbaw 10 Appendix D Filter Values and Data Rates A table containing some filter values and corresponding data rates resolution and frequency tested on CXM543 is provided below Table 5 CXM543 Filter Values and Data Rates Filter Measur A D Single A D All A D 3db Value ed Text Axis Sample Axis Sample Resoluti Frequency Data Rate sec rate sec on in Hz rate bits sec 8000 2 06 150 2 08 19 3 94 6000 2 77 200 2 77 19 7 8 4000 4 1 300 4 16 19 11 7 3000 5 5 400 5 55 15 6 2000 8 17 600 8 33 18 5 23 4 1800 10 8 800 8 33 31 2 1000 16 0 1200 16 7 17 5 46 8 900 21 5 1600 16 7 62 4 800 31 5 2400 22 2 17 93 6 600 41 1 3200 44 4 124 8 400 512 4800 66 7 187 2 300 61 3 6400 88 9 249 6 8002 150 50 16 39 3 6002 200 66 7 15 5 524 4002 300 100 15 5 78 6 3002 400 133 15 104 8 2002 57 7 600 200 15 157 1002 73 0 1200 400 14 314 802 88 4 2400 800 12 5 629 402 97 2 4800 1600 10 5 1260 282 104 9 7680 2560 9 5 1676 4 NOTE CXM543 is limited by its CPU clock speed rather than either A Ds or baud rate Doc 7430 0115 01 Rev A Page 29 Crossb w CXM543 User s Manual 11 Appendix E Warranty and Support Information 11 1 Customer Service As a
22. hard iron corrections do not need to be precise in fact a set of random orientations will usually work The accuracy of the correction is better for some sets of orientations than for others however so the CXM543 software leads the user through a set of orientations which are known to work well The ability to use orientations that are not precisely set greatly eases use in the field Two versions of hard iron measurement are available one for three dimensional orientations and another for the case where the platform moves in only two dimensions The two dimensional case would apply to land vehicles for example where only azimuth is varied On the other hand if roll pitch and azimuth are all varied as is often the case for airborne platforms the three dimensional corrections would be needed Slightly different data are accumulated depending upon whether a 2 or 3 dimension correction will be determined so best results are obtained if the dimension is specified before the procedure begins The three dimensional data do allow for the determination of a two dimensional correction at slightly reduced accuracy but the two dimensional data are not sufficient to measure the three dimensional correction 9 2 Setup Procedure The CXM543 is calibrated at the factory and no hard iron offset should exist unless it is rigidly mounted to a movable platform The movements of the CXM543 to be described require that the entire platform be moved with it I
23. he CXM543 mode is selected to be corrected the transmitted data mode must be further specified as follows M v vector mode M a angle mode When M v the magnetometer sensor outputs in Gauss and the accelerometer sensor outputs in Gs are transmitted When M a the CXM543 orientation roll pitch and azimuth angles are transmitted For both vector and angle mode the format of the data can be selected as follows Page 14 Doc 7430 0115 01 Rev A CXM543 User s Manual Crossb w M b _ binary mode M d decimal ASCII mode For decimal mode ASCII characters representing the data are transmitted For binary mode the data is encoded in binary format Decimal mode is ideal for use when the CXM543 is communicating with a PC because the ASCII characters display in intelligible form on a PC running a terminal emulation program e g PROCOM or HyperTerminal Binary mode uses a considerably smaller number of bytes to encode the data and is hence much faster than decimal mode Binary mode characters however do not display in an intelligible way on a PC and must be decoded using a separate program Binary mode is used principally for systems where an embedded microprocessor communicates with the CXM543 In calibrated vector decimal mode M cvd the data format is as follows AX AY AZ MX MY MZ T K lt CR gt lt LF gt AX is the X accelerometer output etc and is of the form X XXXXX where X is an ASCII character For instance
24. hecksum to the transmission M E or omit this MN Some examples of different data output formats and the commands used to create them follow Commands Data Formats M T Raw data in a text hex format without a checksum M R AX AY AZ MX MY MZ M N 1234 5678 9ABC 1234 5678 9ABC lt CR gt lt LF gt The data values are encoded as four digit hex values separated from each other with a single space The last digit of the Z data is followed by a carriage and a line feed T Raw data in a text hex format with a checksum cs M R AX AY AZ MX MY MZ cs M E 1234 5678 9ABC 1234 5678 9ABC 4E lt CR gt lt LF gt This just like the last example except for an addition of a space and a two Hex digit checksum in between the last digit of Z and the carriage return The checksum is composed of the sum of all of the digits in all the data values M T Corrected data in a text decimal format without a checksum M V AX AY AZ Mx MY MZ M N 0 23456 0 78900 0 23997 0 98765 0 53210 0 12345 lt CR gt lt LF gt Doc 7430 0115 01 Rev A Page 7 Crossb w CXM543 User s Manual The X Y amp Z values are encoded as decimal values in Gauss Each is separated from the next with a single space The last digit of the Z data is followed by a carriage return and a line feed M T Corrected angle data in a decimal format without a checksum M A Roll Pitch Azimuth Tot Acc Tot Mag M N 100 00 190 00 180 00 1 00000 0 49543 lt CR gt lt LF gt The angle data
25. is in degrees Each value is displayed as a 3 digits point 2 digits value XXX XX separated by a space from the next value The total field is displayed in G s and the total magnetic field is displayed in Gauss M T Corrected angle data in a decimal format with a checksum M A Roll Pitch Azimuth Tot Acc Tot Mag CS M E 100 70 190 05 1 12 1 00000 0 49543 35 lt CR gt lt LF gt The angle data is in degrees Each value is displayed as a 3 digits point 2 digits value XXX XX separated by a space from the next value The total field is displayed in Gs and the total Mag field is displayed in Gauss This is followed by a two hex digit check sum M B Corrected vector data in a binary format with a checksum MzV AX AY AZ MXMYMZ CSEOT M E 123456789A4987654322 FEBCID5A The data values are encoded as two byte values followed by a checksum consisting of the lower eight bits of the sum of the bytes comprising all the data This is followed by a synchronization byte of 5A The checksum is calculated as follows 1243445647849 A498 764 544 3242 FE BC ID When the binary mode is used the sensor outputs in Gauss and Gs and the angle values in degrees can be obtained as follows 1 Magnetometers Divide binary output which is a signed integer by 32768 to obtain Gauss 2 Accelerometers Divide binary output which is a signed integer by 16384 to obtain G Page 8 Doc 7430 0115 01 Rev A CXM543 User s Manual Crossb w 3 Ang
26. les Divide binary output which is an unsigned integer by 182 to obtain degrees For example if the X magnetometer output in binary is 12AF this is equivalent to 4783 decimal To obtain the X output in Gauss divide by 32768 to obtain 0 14597 Gauss For a binary output of F2AF 3409 decimal the sensor output is 0 10403 Gauss This is followed by a checksum consisting of the lower eight bits of the sum of the bytes comprising the X Y amp Z Data for accelerometers and magnetometers and calculated as sum of all bytes except checksum and 5A 256 Checksum This is followed by a synchronization byte of 5 A which represents the end of the data packet 4 NOTE The sensor outputs from 0000 to 7FFF are positive and outputs from 8000 to FFFF are negative 8000 represents the decimal number 32768 and FFFF represents the decimal number 1 To determine the mode of a CXM543 issue the command M The autosend command A enables data to be sent continuously upon power on The output rate of the sent data is set by issuing the command of the form fi where is a single digit integer between 0 slow and 9 fast Different filter values and corresponding data rates resolution and frequency are provided in Appendix B When the CXM543 is set to the slowest rate f0 data is transmitted at a rate of about I sample sec when the pacing value is 0000 If slower rates are desired the user can set the pacing value This ranges f
27. ode Because the H2 and H3 commands automatically set the dimension this would only be used if a user wanted to use his own set of orientations without being prompted Any data gathered is lost and data acquisition is restarted 9 5 Three dimensional Correction To determine a 3 dimensional offset begin by typing H3 followed by a carriage return The CXM543 will then prescribe a set of 6 orientations The prescribed orientations and their interpretation in up down front back left side and right side are as follows replies from the CXM543 are enclosed in quotation marks Place the sensor z axis down to start a 3D correction then type HP if possible place the x axis toward north Any direction will do but it should remain the same throughout the procedure This will be called north even though it may not be true north Type HP followed by a carriage return Rotate 90 degrees about the y axis so the x axis points up then type HP Page 26 Doc 7430 0115 01 Rev A CXM543 User s Manual Crossb w Set the platform on its backside with the sideways direction remaining unchanged and the bottom facing north Type HP followed by a carriage return Rotate 90 degrees about the y axis so the z axis points up then type HP Place the platform upside down with the x axis pointing south Type HP followed by a carriage return Rotate 90 degrees about the y axis so the x axis points down then type HP The f
28. oughout the procedure This will be called north even though it may not be true north Type HP followed by a carriage return Rotate 90 degrees clockwise about the z axis then press HP The forward direction should now face east Type HP followed by a carriage return Rotate 90 degrees clockwise about the z axis then press HP The forward direction should now face south Type HP followed by a carriage return Rotate 90 degrees clockwise about the z axis then press HP The forward direction should now face west Type HP followed by a carriage return At this time the CXM543 will automatically calculate the hard iron offsets and display them Also displayed is a set of parameters indicating the quality of the fit If the residuals without correction are substantially larger than those with correction this indicates that the hard iron correction would improve orientation accuracy The hard iron correction can be turned on by typing HI followed by a carriage return 9 7 Caveats The hard iron correction will not be accurate unless the magnetic environment is of a uniform field other than the hard iron field The data obtained near large magnetic objects not on the platform will not be accurate for example The correction will only be accurate if the sensor has been calibrated for scale and orthogonality which is normally the case In some cases highly permeable material on the platform can interfere wit
29. rom 0000 fast to FFFF slow The pacing value is set by issuing a command P GHHHE The user can set the baud rate of the CXM543 to the standard values from 300 to 76800 baud The baud rate command is of the form B XXXX lt CR gt lt LF gt A complete list of the CXM543 commands can be found in Appendix B Doc 7430 0115 01 Rev A Page 9 Crossb w CXM543 User s Manual 6 Description of the CXM543 Orientation Angles The roll angle of the CXM543 is zero when the Y axis sensors are oriented horizontally A drawing showing the CXM543 in a roll orientation of 90 Y sensors down is shown in Figure 1 Roll 90 degrees Horizontal Down Figure 1 CXM543 Roll Definition The pitch angle of the CXM543 is defined as 0 when the X axis sensors are pointed down and 180 when the X axis sensors are pointed up The X sensors are aligned with the CXM543 package and point along the package edge shown in Figure 1 Figure 2 illustrates the CXM543 positioned at an inclination angle of 127 Horizontal Inc 90 deg Inclination 127 degrees Down Inc 0 deg Figure 2 CXM543 Pitch Definition Page 10 Doc 7430 0115 01 Rev A CXM543 User s Manual Crossb w The azimuth angle of the CXM543 is referenced to magnetic North and is zero when the projection of the CXM543 X axis in a horizontal plane is oriented North A diagram showing the CXM543 system oriented at an azimuth of 45 is shown in Figure 3 A
30. ront should face down and the top should face north Type HP followed by a carriage return Rotate 90 degrees about the z axis so the y axis points up then type HP Rest the platform on the left side with the top facing north Type HP followed by a carriage return Rotate 180 degrees about the z axis so the y axis points down then type HP Rest on the right side with the top facing north Type HP followed by a carriage return At this time the CXM543 will automatically calculate the hard iron offsets and display them Also displayed are a set of parameters indicating the quality of the fit If the residuals without correction are substantially larger than those with corrections this indicates that the hard iron correction would improve orientation accuracy The hard iron correction can be turned on by typing HI followed by a carriage return 9 6 Two dimensional Correction To determine a two dimensional correction begin by typing H2 followed by a carriage return The CXM543 will then prescribe a set of 4 orientations The top of the platform will always point up so we only need to specify the direction of the front The prescribed orientations and their interpretation in up down front back left side and right side are Doc 7430 0115 01 Rev A Page 27 Crossb w CXM543 User s Manual Place the sensor z axis down to start a 2D correction then type HP Any initial direction will do but it should remain the same thr
31. the CD ROM drive 2 Findthe MagView folder and copy it over to your desktop and the software ready to use If you have any problems or questions you may contact Crossbow directly 3 2 Connections The CXM543 is shipped with a ribbon cable to connect the sensor to a PC COM port 1 Connect the 9 pin end of the digital signal cable to the port on the CXM543 2 Connect the other 9 pin end of the cable with backshell to the serial port of your computer 3 The additional black and red wires on the cable supply power to the Sensor Match red to power and black to ground The input voltage can range from 7 5V to 15 VDC See the specifications for your unit Doc 7430 0115 01 Rev A Page 3 Crossb w CXM543 User s Manual WARNING Do not reverse the power leads Applying the wrong power to the Sensor can damage the unit Crossbow is not responsible for resulting damage to the unit 3 3 Setup MagView With the Sensor connected to your PC serial port and powered open the Mag View software 1 From the MagView main display click on Configure button and select the correct COM port Baud Rate default is 9600 and Sensor model You can log data to a file by entering a data file name 3 Youcan also administer various Sensor Settings and Special Settings via this Configure screen and save settings 4 The main screen provides the graphical visualization of various sensor parameters that can be checked from Graph m
32. there is no terminating transmission of a carriage return or linefeed Instead and end of transmission character 5A is transmitted In raw integer mode the transmission is of the following form MX MY MZ AX AY AZ T K lt CR gt lt LF gt MX is a 5 digit ASCII number representing the X magnetometer count output This can range from 32768 to 32767 T represents the system temperature and is of the form TT T where the T s are ASCII characters representing the system temperature in C The K is a one byte checksum obtained by adding up all of the ASCII data characters in the transmission excluding signs spaces and decimal point and taking the least significant byte of the sum A space ASCII character is transmitted after each sensor output 8 3 Checksum Calculation Calculation of the checksum generally involves summation of the digits of the transmitted data disregarding decimal points and signs The method of summation is different from the binary data and decimal ASCII data formats For decimal data the individual digits of the transmitted data are summed For example consider the following vector data transmission in decimal format mode cvd Page 18 Doc 7430 0115 01 Rev A CXM543 User s Manual Crossb w M EXAMPLE AX AY AZ MX MY MZ CS lt CR gt lt LF gt 4 23456 12345 0 27561 0 47510 0 51235 0 12345 68 The checksum is computed as follows 2 3 4 5 6 1 2 3 4 5 2 7 5 6 1 4 7 5 1 5 1 2 3 5
33. ut Pin Function Not used RS 232 Transmit Data RS 232 Receive Data Not used Ground TTL Serial Out TTL Serial In Factory Use Only Input Power 7 5V to 15VDC YO CO JN ID tA JH IN Je A drawing showing the dimensions and mounting hole location of the CXM543 is shown in Appendix A Page 2 Doc 7430 0115 01 Rev A CXM543 User s Manual Crossb w 3 Quick Start 3 1 MagView Software The purpose of the Sensor interface program is to provide a graphical output interface to the CXM543 Orientation Sensor and allow the user to configure and operate the sensor The Mag View interface program allows the sensor to be monitored in every mode that the sensor can be programmed The sensor can be programmed to allow for ASCII or BINARY transfer mode and corrected or non corrected data Log files of sensor data can be created A scrolling graph of the digital data and graphical indicators of the angular data are displayed to the operator Minimum and maximum values are maintained for the magnetometer and the accelerometers 3 1 1 MagView Computer Requirements The following are the minimum capabilities that your computer should have in order to run MagView successfully e CPU Pentium Class e RAM 32MB minimum 64MB recommended e Operating System Windows 98 NT4 2000 XP 3 12 Install MagView To install Mag View software on to your computer 1 Insert the CD Support Tools in
34. vailable until HC is used again even if the sensor has begun to accumulate data for another correction The command reports the residuals both with and without the use of a hard iron correction Small residuals indicate a good fit to the data A hard iron correction should be used when the residual with hard iron is much smaller than the residual without If the residuals are comparable this indicates that the hard iron correction is too small to be Doc 7430 0115 01 Rev A Page 25 Crossb w CXM543 User s Manual determined with the data gathered and usually is sufficiently small that use of the correction is not indicated HW Where is a number 0 10 hereinafter referred to as the weight This number sets the way corrections are calculated The corrections make maximal use of accelerometer data if the weight is 10 and use only magnetometer data if the weight is 0 The degree to which accelerometer data is used increases gradually with the specified weight In actual use this command would rarely be used as the default value of 5 works well for most situations H Gives the hard iron data in use the number of data points gathered the dimensionality etc as well as additional help HQ Quit the present data collection discarding all data gathered so far The correction if any resulting from the last HC command will continue to be available and can be turned on or off with the HI command HT Toggle between 2D and 3D m
35. y issuing the commands S CR M V A CR The sensor data is transmitted with the format AX AY AZ MX MY MX where AX is the X accelerometer output MX is the X magnetometer output etc All accelerometer outputs should range between 1 down and 1 up The magnetometer outputs should range from about 0 45 Gauss to 0 45 Gauss Transmission speed can be changed from among 9 different values by issuing commands of the format fi where can be set between slowest speed and 9 highest speed Different filter values corresponding to the f command are as listed in the Table 2 below Different filter values and corresponding data rates resolution and frequency are provided in Appendix D Table 2 CXM543 Filter Commands Command Filter Value fl 8000 f2 4000 f3 2000 f4 1000 f5 2002 f6 1002 f7 802 f8 402 f9 282 Page 6 Doc 7430 0115 01 Rev A CXM543 User s Manual Crossb w 5 CXM543 Configuration and Data Formats The user can configure the CXM543 system in the following ways 1 Mode 2 Autosend or command 3 Baud rate 4 Pacing The mode settings are used to change the format of the data output The user can select the data output to be raw A D counts M R calibrated sensor vector output M V or angles M A The serial output format can be selected to be text M T or binary M B The user can also choose whether to append a c
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