CXM544 Orientation Sensor
Contents
1. DOCDOM MCU DSP ARMVFPGA lt l2. http www sensor ic com http www pc ps net http www suns tare com HTTP www rfo e net www icasic c om www sunstars ony 1602 0755 83370250 83376489 83376549 83607652 83370251 82500323 0755 83376182 0 13902971329 MSN SUNS8888 hotmail com 518033 E mail szss200163 com QQ 195847376 2583 0755 83665529 25059422 0755 83394033 13501568376 132 3097 TEL 010 81159046 82615020 13501189838 FAX 010 62543996 668 2B35 TEL 021 28311762 56703037 20 Pr 13701955389 FAX 021 56703037 P
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4. NUMDATABYTES MX AX MY AY MZ AZ MT AT 0 5 DATACHKS UM gt lt END gt size 8b 16b 16b 16b 16b 16b 16b 16b 16b 8b 8b 16b in bits If The Command is 131 NUM DATA BYTES gt lt Roll gt lt MRoll gt lt Pitch gt lt Mag gt lt Head gt lt Grav gt lt MT gt lt AT gt lt 0 gt lt DATA CHK SUM gt lt END gt size 8b lob 16b 16b 16b 16b 16b 16b 16b 8b 8b 16b in bits END Ox7FFF is unique in the data stream NUM DATA BYTES 16 0 a constant 0 to allow END to be unique DATA CHECK SUM The lower 8 bits of the sum of all the bytes in the data area Roll The Roll data encoded as below Pitch The Pitch data encoded as below Head The Heading data encoded as below Crossbow Technology Inc Page 21 SUNSTAR O O http www sensor ic com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 63 con SUNSTAR O E OO http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 lt MRoll gt The Magnetic Roll data encoded as below lt Mag gt The Total Magnetic Field data encoded as below lt Grav gt The Total Gravitational Field data encoded as below lt MX gt lt MY gt lt MZ gt The Mag data encoded as below lt AX gt lt AY gt lt AZ gt The Acc data encoded as below lt MT gt lt AT gt The Temp data encoded as below All data is sent most significant byte first If
5. 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 Inclination Down Figure 5 544 Coordinate System North Magnetic Roll 30 as shown UP Roll 20 as shown 544 Reference 544 Surface Reference Wires Surface Wires 2 Figure 6 544 Orientation Angles Crossbow Technology Inc Page 13 SUNSTAR O O http www sensor i c con TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 163 con SUNSTAR O E O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 10 4 Calculation of Roll and Magnetic Roll The roll angle 0 is determined by using the following equations 0 lt 0 lt 27 Cos 48 8 Sing VS 8 Tan 9 PESA E Roll is 0 when g 0 and g gt 0 Roll is 27 radians when g 0 and g lt 0 When the X axis is near vertical pitch lt 5 the quantities g and g become very small and the above expressions yield a less accurate value of 0 In this situation magnetic roll is often used to determine the angular orientation of the CXM544 about the longitu dinal X axis Magnetic roll Om is given by the following 0 lt 0 lt 27 H Sino JH H Cos0 H H H Tan 0 H Crossbow Technology Inc Page 14 SUNSTAR O O http www sensor i c com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 63 con SUNSTAR
6. O E O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 10 5 Calculation of Inclination Inclination is determined from the following equations 0 lt n Cos Bx 8 g 8 Sing 8 2 2 Juge Sa Ex where g 8 8 8 Inclination is 0 when the CXM544 x axis is pointed down and 7 2 radians when horizontal 10 6 Magnetic Heading Azimuth Yaw We first give expressions for the magnetic field in a horizontal reference defined by xl yl zl where x1 is aligned with the projection of the CXM544 x axis in the hori zontal plane and z1 is down H lg g H 2 8 H g 8 im gs 8 H R Hugo cut gm 1 y PE Eg B _ H 8 H g Hg za 8 Magnetic heading is then given by 0 lt lt 27 H Co H H xl yl Sin gt JH H Crossbow Technology Inc Page 15 SUNSTAR O http www sensor i c com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20G163 con SUNSTAR O E O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 Tan a _ H 2 H g g ES 2 2 Ha H Ey t8 H g HB Magnetic heading is 0 when the CXM544 x axis points North and 7 2 radians when it points East 11 Using The CXM544TOOL Software 11 1 Basic Description This DOS program exercises the basic functions
7. 8SC A 00000 6T1 SC A 00000 8 8SC A 00000 L X DOV 00000 L X OV 9SION 00000 81 SC X YYV 00000 6 8SC X D VI e eq umurxe A 00000 61 SC X YYV 00000 8 8SC X D VI amp jeq umururjv 00000 81 SC X YYV 00000 8 8SC X 5 VIN ejeq WIIN pI Sjuno 60 00 00 PWLL uone num y 00 SOUL T poseIoAV S unoO ur ezed sey SI Jndjno TEOT TA DPS Sd V I9POIN Aejdsig u i5S leoldAL p o1nDiJ Page 17 Crossbow Technology Inc SUNSTAR O O http www sensor ic com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 63 con SUNSTAR O E O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 M Increment data correction mode from raw to scaled to final corrected to angular data Add one to the number of averages done on data Subtract one from the number of averages done on data Print the Current Data Maximums Minimums and Noise Write the Current Data to a data file Hold the display and the program until a key is pressed Start the process of requesting and reading calibration data See the Calibration section for more information Change to a mode for displaying storing and changing constants internal to the sensor At the current time few of these constants are used and those that are preset to their correct values so this mode is of little use Q Ams 11 3 Troubleshooting If
8. Mag Base Ortho Y X Crossbow Technology Inc Page 23 SUNSTAR O O http www sensor ic com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 163 con SUNSTAR O E O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 26 Mag Base Ortho Y Y 27 Mag Base Ortho Y Z 28 Mag Base Ortho Z X 29 Mag Base Ortho Z Y 30 Mag Base Ortho Z Z 31 Acc Base Ortho X X 32 Acc Base Ortho X Y 33 Acc Base Ortho X Z 34 Acc Base Ortho Y X 35 Acc Base Ortho Y Y 36 Acc Base Ortho Y Z 37 Acc Base Ortho Z X 38 Acc Base Ortho Z Y 39 Acc Base Ortho Z Z 40 Bow Correction X 4 Bow Correction Y 42 Bow Correction Z 00 Command Echo Flag 0 is no command echo anything else echo commands 01 Autostart Flag If OxSA executes the selected autostart option on powerup 02 Correction Level 0 Raw 2 Vectors 3 Angles In Angles mode Roll is labeled MX Pitch is labeled MY Heading is Labeled MZ Mag Roll is labeled AX Total Mag Field is labeled AY Total Grav Field is labeled AZ 03 Months since 1 90 when device was calibrated 04 Version of the Calibration Software used 05 Power on self test flag If zero a self test will be done on power up 06 Enable extended error messages 07 This Sensor s Address Number 0 36 gt 0 9 A Z 08 Auto Start Mode on powerup start accepting commands then 0x00 Send all data i
9. Value Ortho TableOrtho 24 lt Byte 22 gt 22 The Table Acc Ortho Scale Value Ortho TableOrtho 24 lt Byte 23 gt 23 Not Used 24 Product I D String char 1 25 Product I D String char 2 26 Product I D String char 3 27 Product I D String char 4 28 Product I D String char 5 29 Product I D String char 6 30 Product I D String char 7 3 Product I D String char 8 32 Product I D String char 9 33 Product I D String char 10 34 Constant 0 35 RTS Delay is the time in 2 millisecond units that the RTS line is high before data is sent Any value but 0 will slow the data rate by the same amount Crossbow Technology Inc Version 1 4 Page 25 SUNSTAR O O http www sensor ic com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 63 con SUSTARG D O O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 63 con SUNSTAR 10 IC
10. Writes an Enabled lt CR gt lt LF gt lt EOT gt Write Float To Constant WC lt Constant Number gt F lt Value gt Done lt CR gt lt LF gt lt EOT gt Write Byte To Constant WC lt Constant Number gt B lt number gt Done lt CR gt lt LF gt lt EOT gt Crossbow Technology Inc Page 20 SUNSTAR O O http www sensor ic com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 163 con SUNSTAR O O O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 Write Int To Constant WC Constant Number gt B lt number gt Done lt CR gt lt LF gt lt EOT gt All Commands marked with an require the Enable Low Level Writes command to be exe cuted as the previous command for successful execution All Commands Marked with a execute differently when Enable Low Level Writes was exe cuted as the previous command 128 Send AII Data as Vectors in a Binary Format 129 Send AII Data as Vectors in a IEEE Float Format 131 Send AII Data as Angles in a Binary Format 132 Send AII Data as Angles in a IEEE Float Format 128 and 131 Sends AII Data in an encoded Binary Format in the current format as selected by Byte constant 2 If the correction mode is 0 1 or 2 the data is returned as lt lt lt lt Sent First c cc cSent Last lt lt lt lt If The Command is 128
11. after starting the software you get a series of error messages rather than the data screen wait for about twenty seconds You will be asked to enter a new serial port Enter a new com port number and press return to retry or press escape to exit If you have a communication error this can be caused by The sensor s power is off Turn the sensor on and press return The serial cable is unplugged Plug it in and press return The wrong serial port number was Enter the correct poet number and used press return The cable is wired incorrectly The Correct the cable or install a null sensor is configured as a DTC device modem and press return and so requires a null modem or a ca ble that reverses 2 amp 3 between it and your computer Your P C serial port is non standard Configure your port as COMI or or not configured as COMI or COM2 CON2 and your interrupt as INT 3 or INT 4 If the program starts fine but then locks up or displays errors on the screen you may have a loose connection in your serial cable or at the connector you may require a shielded cable or your cable may be too long less than 25 are recommended Crossbow Technology Inc Page 18 SUNSTAR O O http www sensor ic com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 163 con SUNSTAR O E O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 Heading Sensor Command Set CX
12. of the Model CXM544 Miniature Angular Orientation Sensor and applies some post processing to the data This program is not shipped with the sensor but can be provided upon request 11 2 Using the Software The compiled program is called CXM544TOOL EXE It requires one parameter the comm port number that the Position Sensor is connected to For example to select COMI enter a parameter of 1 To start the program from the command line change the directory to where the program is stored and enter CXM544TOOL followed by a space and then the com port number If there are no communication problems with the sensor you will now see a screen resembling the one shown in Fig 4 If you don t see this but get a series of errors and are asked to enter a new port number or retry go to the trouble section later in this description The sensor data screen is comprised of a status header a data display area and a command footer The first line of the status header has the model number of the unit or APS if this is a prototype Next to this is the software version number of the software in the sensor To the right of this is a description of the corrections applied to the data Raw Data Scaled amp Off set Ortho Corrected Angular Data or Distance from Table Next is the number of times the data is averaged On the far right is the display of the current reading of this average On the second line the accumulated time since the Maximum Minimum and Nois
13. roll angle total magnetic field and total gravitational field The total field numbers are of interest because they are the same for all orientations of the sensor since VAX AY AZ 1 0 Gee NM MY MZ 5Gauss The degree to which these field magnitudes are constant for different orientations is a meas ure of the accuracy of the sensor The actual magnetic field amplitude reported will vary somewhat depending on location This value ranges from 0 4 to 0 6 Gauss over the earth s surface It is also possible to configure the system mode to output raw A to D counts This can be ac complished by setting byte 02 0 In order to observe the value of any internal system constant send the commands 0S8C02b CR 0SC b CR The first command results in the value of byte constant 02 being transmitted The second command evokes a response containing the values of all byte constants The CXM544 can transmit data in two formats 1 text and 2 binary Text transmissions are formatted to display correctly when the CXM544 is connected to a PC running a terminal emulator program e g PC PLUS HyperTerminal etc Binary transmissions are faster than text transmissions and are more suited to interfacing the CXM544 to a microprocessor sys tem In command mode binary transmissions are initialed by sending a single byte to the CXM544 e g ASCII 128 or ASCII 129 The CXM544 has an autosend mode which enables data to automatically be se
14. 489 FAX 0755 83376182 E MN L szss20G163 con SUNSTAR O E O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 The currently supported binary commands and their definitions follow Command Definition send sensor data in binary format send sensor data in IEEE 32 bit format send angle data in binary format send angle data in IEEE 32 bit format The CXM544 response to these commands is of the following form number of data bytes MX AX MY AY MZ AZ MT AT 0 data check sum gt lt end gt Refer to the next section of this manual Heading Sensor Command Set for a more detailed discussion of the data format for binary transmissions 5 Initial Setup of the System In order to operate the CXM544 power must be applied to it and an interface with an exter nal computer must be set up Powering will depend upon whether the unit is using a 45V supply or the internal regulators and powers from 7VDC to 12VDC To ensure system accuracy the 5V powered system must be within 0 05V of 45V Connect the correct power lead to the selected supply voltage See Figure 2 After powering the system should consume about 71 ma of input current In order to set up a computer interface with the system select the output protocol of the CXM534AA This can be either TTL or RS232 The TTL protocol is usually used in microproc essor
15. 5G and 0 5G In the Northern hemisphere the direction of the earth s magnetic field is North with an inclination of about 60 For instance if the system X axis is pointed to magnetic North and inclined about 60 into the earth 30 from vertical the X magnetometer output should read 0 5 Gauss Crossbow Technology Inc Page 11 SUNSTAR O O http www sensor ic com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20G163 con SUNSTAR O O O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 10 Determining Orientation Angles from CXM544 Accelerometer and Magnetometer Data This application note describes how to calculate the roll pitch and azimuth angles for the CXM544 orientation sensor from accelerometer and magnetometer output data 10 1 Sensor Based Coordinate System 10 2 The coordinate system of the CXM544 system is defined in Fig 5 The accelerome ter and magnetometer coordinate systems are both aligned with the physical package coordinate systems shown For the magnetometer sensors a positive output voltage will result if the sensor is pointed north For the accelerometers a positive voltage will result if the sensors are pointed down Definition of Orientation Angles The orientation angles are defined in Fig 5 and 6 Azimuth or yaw is defined as the angle measured from magnetic north clockwise from above to the projection of the
16. EEINITIONS 3 10 4 CALCULATION OF ROLL AND MAGNETIC ROLL 10 5 CALCULATION OF INGLINATION 00 re AA E E R EE R 10 6 MAGNETIC HEADING AZIMUTH YAW Ne USING THE 544TOOL SOFTWA RE TAT BASIC DESCRIPTION SS erri usa RU ER ER HEU E a s 11 2USING THE SOFTWARE A SA ELODA D 0 e bada SUNSTAR O O http www sensor ic com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 63 con SUNSTAR O O O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 1 Introduction The CXM544 Orientation Sensor system contains both a 3 axis fluxgate magnetometer and a 3 axis accelerometer The combination of these two sensor systems enables the roll pitch and azimuth angles of the CXM544 reference frame with respect to the local gravity and magnetic field vectors to be determined Roll and pitch angles are determined from the ac celerometer subsystem which measures the orientation of the system with respect to the gravity vector After roll and pitch are known the magnetometer subsystem is used to deter mine the azimuth angle of the system Knowledge of the roll and pitch angles enable deter mination of the horizontal components of the earth s local magnetic field this information defines the azimuth angle The CXM544 system also contains a microproce
17. F gt lt EOT gt Crossbow Technology Inc Page 19 SUNSTAR O http www sensor ic com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20G163 con SUNSTAR O E O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 Reset A D RA Done lt CR gt lt LF gt lt EOT gt Test ROM Checksum TC if low level writes are enabled the output is STORED HHHH lt CR gt lt LF gt lt EOT gt If low level writes are not enabled and the Checksum of the ROM is the same as the ore stored HHHH lt CR gt lt LF gt lt EOT gt else the Output is ERR HHHH lt CR gt lt LF gt lt EOT gt Test EEROM Checksum TE if low level writes are enabled the output is STORED HHHH lt CR gt lt LF gt lt EOT gt If low level writes are not enabled and the Checksum of the ROM is the same as the one stored HHHH lt CR gt lt LF gt lt EOT gt else the Output is ERR HHHH lt CR gt lt LF gt lt EOT gt Test RAM TR Either an OK or an error OK lt CR gt lt LF gt lt EOT gt The Error Addr is in Hex ERR AT HHHH lt CR gt lt LF gt lt EOT gt Test EEROM Read Write TW This takes up to 10 Secs Either an OK or an error OK lt CR gt lt LF gt lt EOT gt The Error Addr is in Hex ERR AT HHHH lt CR gt lt LF gt lt EOT gt Test Serial Port TS Always Echoes OK lt CR gt lt LF gt lt EOT gt Return Software Version TV Ver 44 lt CR gt lt LF gt lt EOT gt Enable Low Level
18. Inc Page 22 SUNSTAR O O http www sensor ic com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 163 con SUNSTAR O E O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual 0 DATA CHECK SUM Roll Pitch Head lt MRoll gt lt Mag gt lt Grav gt lt MX gt lt MY gt lt MZ gt lt AX gt lt AY gt lt AZ gt lt MT gt lt AT gt Version 1 4 a constant 0 to allow END to be unique The lower 8 bits of the sum of all the bytes in the data area The Roll data The Pitch data The Heading data The Magnetic Roll data The Total Magnetic Field data The Total Gravitational Field data The Mag data The Acc data The Temp data All data is sent most significant byte first Ortho Constants are designated Result Axis first Component Axis Second 00 Anal Scale 01 Temp Scale 02 Anal Offset 03 Temp Offset 04 Mag Base Offset X 05 Mag Base Offset Y 06 Mag Base Offset Z 07 Acc Base Offset X 08 Acc Base Offset Y 09 Acc Base Offset Z 10 Mag Base Scale X 11 Mag Base Scale Y 12 Mag Base Scale Z 13 Acc Base Scale X 14 Acc Base Scale Y 15 Acc Base Scale Z 16 Mag Scale2 X 17 Mag Scale2 Y 18 Mag Scale2 Z 19 Acc Scale2 X 20 Acc Scale2 Y 21 Acc Scale2 Z 22 Mag Base Ortho X X 23 Mag Base Ortho X Y 24 Mag Base Ortho X Z 25
19. M544 V3 18DFX 1 00 544 Addressed Command is Address Command CR An Address is 0 9 A Z gt CR is a Carriage Return Axis is X ZI T gt Constant Number is 00 99 gt Constant Value is lt lt number gt lt number gt gt Constant String is lt A Z 0 9 gt lt Constant String gt A number is lt lt 0 9 gt number gt A command consists of one of the following Send All Data SD All Data is sent MX AX HHHH lt CR gt lt LF gt as requested MY 4 HHHHE AY HE HH lt CR gt lt LF gt raw vectors or MZ Ht JHHHHE AZ THBHHHESCRS LE angles as set by MT HHHHHHi lt CR gt lt LF gt byte constant 2 AT HHE HHEI lt CR gt lt LF gt lt EOT gt Send Anal Input SA ANA iHHHHHi lt CR gt lt LF gt lt EOT gt Read Float Constant SC Constant Number gt F HHHH E lt CR gt lt LF gt lt EOT gt Read All Float Constants SC F OO HHHHHH E lt CR gt lt LF gt 01 BEHHHHHHEEEIHIECRP LE THE tE lt CR gt lt LF gt lt EOT gt Read Byte Constant SC lt Constant Number gt B lt CR gt lt LF gt lt EOT gt In Hex Read All Byte Constants SC B 00 lt CR gt lt LF gt In Hex 01 lt CR gt lt LF gt lt EOT gt lt CR gt lt LF gt lt EOT gt Read int Constant SC Constant Number gt I lt CR gt lt LF gt lt EOT gt Read all Int Constants SC I 00 lt CR gt lt LF gt 01 lt CR gt lt LF gt lt EOT gt THE HH lt CR gt lt L
20. SUNSTAR DD OO http www sensor ic con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 CXM544 Orientation Sensor User s Manual Revision 1 4 May 2001 Crossb w Crossbow Technology Inc 41 E Daggett Drive San Jose CA 95134 408 965 3300 408 324 4840 Fax SUNSTAR O O http ww sensor i c com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 3163 con SUNSTAR O E O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXMS44 ORIENTATION SENSOR Table of Contents 1 INTRODUCTION smn assii a an NEA ENEE ea 2 2 SYSTEM SPECIFICATIONS eese eee ee ten enentate nean tantu nente tenen essen es tanen enses to senes sna n nente tenen nans 3 3 MECHANICAL FEATURES 00 4 4 ELECTRICAL INTERFACE wu bid dd ei dd 4 5 INITIAL SETUP OF THE SYSTEMiiiooonsnssosnmismonnansnnmnnonoumniFnu 5 6 OPERATION OF THE SYSTEM 000 em sss 6 7 DESCRIPTIONS OF THE SYSTEM INTERNAL CONSTANTS 8 8 CHANGING THE BAUD RATE 0000 beita 9 9 VERIFYING PROPER OPERATION OF THE SYS TELM 9 10 DETERMINING ORIENTATION ANGLES FROM 544 ACCELEROMETER AND 11 MAGNETOMETER DATA di 10 10 1 SENSOR BASED COORDINATE SYSTEM n nus 10 2 DEFINITION OF ORIENTATION ANGLES 103 D
21. age 3 SUNSTAR O O http www sensor ic com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 163 con SUNSTAR O E O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual 2 System Specifications Angular Accuracy 0 to 70 C Azimuth Inclination Roll Temperature Range Operating Power Size Shock Mass Vibration Digital Outputs logic level baud protocol Leads 3 Mechanical Features Version 1 4 1 5 0 5 0 5 0 to 70 C 5V 0 05V 71 ma Or 7 to 12V 71 ma 0 75 x 0 80 x 4 6 750 G 1ms half sine wave 50 grams Random vibrations 10G rms 5 1000Hz TTL or RS232 user programmable up to 9600 baud user selectable ASCII or binary 6 long flying leads An outline drawing of the CXM544 system is shown in Figure 1 The system dimensions are 0 75 x 0 80 x 4 60 1 90 cm x 2 03 cm x 11 68 cm The system is normally mounted by using 4 2 56 x 0 250 long screws to secure the CXM544 reference surface to a flat mating surface Two 0 062 dia x 0 125 long pins protruding from the external mating surface can be used to orient the CXM544 on the external mounting surface The orientation of the X Y and Z axes is shown in Figure 1 The output polarity sense of the axes is such that a field pointing in the direction of the arrows shown in Fig 1 will produce a positive output voltage For example if the X magnetome
22. d three times per second in magnetometer accelerometer out put mode The CXM544 system accelerometers are calibrated by placing the system in a precision rota tion fixture and systematically changing the system orientation in the earth s gravitational field The CXM544 system magnetometers are calibrated by placing the system in a preci sion 3 axis Helmholtz coil system which enables the application of known magnetic fields to the system Both the rotation fixture and Helmholtz coil have alignment pins and reference surfaces which mate to the CXM544 reference surface System calibration can be performed at a base temperature usually 25 C or over a temperature range for example 15 90 C When the system is calibrated over a temperature range data is read from the system at tem perature intervals between the minimum and maximum temperature specification For in stance for calibration over the interval of 15 90 C data is usually read at 25 C temperature intervals between 15 and 90 C The data taken at each temperature includes scale offset and sensor alignment data The recorded data is then used to create a look up table for scale offset and alignment corrections This table is then downloaded into the CXM544 internal EEROM memory where it can be accessed by the system internal microprocessor Correc tions to the read sensor data can then be made by the internal microprocessor system before data is transmitted Crossbow Technology Inc P
23. e or from 45 VDC When the input regulator is used the input voltage can range from 7 to 12V An ideal input voltage which both provides adequate regulation margin and low power consumption is 7 5 V The serial communications interface to the CXM544 is provided by the serial in and serial out lines shown in Fig 2 An external computer talks to the CXM544 on the serial in line and replies from the CXM544 are transmitted out on the serial out line The serial in and se rial out lines operate at TTL or RS232 levels and are normally set to operate at 9600 baud with one stop bit and no parity The user however can change the baud rate by setting bits in the system EEROM See Section 8 Wire Goior Function Rd 7 to 12 VDC Red White 5 VDC Figure 2 Electrical Interface for Model 544 Sensor Two communication protocols are available 1 ASCII and 2 BINARY The ASCII proto col is based upon sending ASCII characters to the CXM544 to obtain data The CXM544 responds by sending out an ASCII data stream complete with carriage returns and line feeds so that it can be easily displayed on a computer terminal The binary protocol is used for high speed computer to computer interchange In this case one byte is sent to request data e g ASCII 128 The CXMS544 then responds with a data packet containing the desired data plus header and checksum Crossbow Technology Inc Page 6 SUNSTAR O O http www sensor ic com TEL 0755 83376
24. e data was zeroed is displayed Next to this is the number of readings taken in this time In the data area there are four data sets The first is the Current Data This reflects the last reading from the sensor averaged and corrected as reflected in the status line The second and third are the Maximum and Minimum Data areas These areas record the largest and smallest values seen in current data area The last area is Noise This reflects the difference between the maximum and the minimum data areas At the bottom of the screen is a list of available commands These are Q Quit Program Esc Quit Program Z Zero reset maximum minimum and noise data areas Crossbow Technology Inc Page 16 SUNSTAR O O http www sensor ic com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 63 con SUNSTAR O E O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con Version 1 4 CXM544 User s Manual 189 ZAX M PIH H 9polW 3u8jsUO 0O ALT 02 IM M Wd d SulgeJ9AV F IPON Bed IUJ IN Sur y X9 A 0197 Z am 9S 10 O 00 c uL 00T uL 00 88L9c L 00 CIIZC L 00 9819c L 007 TI IIZC L 00 9819c L 00 CIIZC L 00000 L Z 00000 Z 00000 8I SC Z 00000 6 8Sc Z 00000 6I Sc Z 00000 L 8SC Z 00000 8I SC Z 00000 8 8SC Z 00000 C A 00000 T A 00000 8T1 SC A 00000 6 8SC A 00000 0c SC A 00000 8
25. inal programs are Procom and ASCII Pro These programs turn the computer into a dumb terminal In this mode whatever you type on the keyboard goes out the selected serial port e g Com 1 and whatever comes in the serial port is displayed on the computer video display If you use HyperTerminal you must select the proper Com port e g COM 1 COM 2 etc and set the baud rate to be 9600 with one stop bit and no parity Set the port up for direct connect and turn off any handshaking The easiest method of determining if a working communications link with the CXM544 has been established is to observe the P C display when the CXM544 is powered up The CXM544 transmits a power up sign on message which should appear in readable form on the P C display The appearance of an unreadable message at power up may indicate incorrect protocol i e TTL instead of RS232 or an incorrect baud rate 6 Operation of the System After establishing communication with the CXM544 data can be obtained from the system by sending typing the command 0SD lt CR gt 0 Send Data The 0 in this sequence is the de fault serial number of the unit After sending this command the CXM544 will respond with an output that appears as follows MX 0 5432 AX 0 9456 MY 0 1234 AY 0 4510 MZ 1 0145 AZ 0 0112 t 45 0 The numbers following the MX MY and MZ headers represent the sensor magnetometer output in Gauss The numbers following the AX AY and AZ headers represe
26. inted down 0 inclination and up 180 Because the CXM544 leads exit the bottom of the unit when the X axis is up it may be awkward to verify this orientation without additional support blocks To verify azimuth accuracy a good compass and an area free from magnetic materials must be located Usually areas inside buildings contain some magnetic material e g metal desks rebar in concrete floors etc In this case verifying azimuth accuracy to 1 is difficult Use a compass to orient the CXM544 approximately horizontal and East inclination 90 azimuth 90 Carefully align the CXM544 long X axis so that it is pointed East and verify that the azimuth reading is 90 1 0 Use the same procedure to verify azimuth accuracy for 180 270 and 0 readings In sensor mode byte 02202 the CXM544 accelerometer sensors should read 1 00 and 1 00 when pointed down and up respectively Therefore when lying flat on a horizontal sur face with the Z axis pointed down the X and Y accelerometers should read 0 0 01 and the Z accelerometer should read 1 00 0 01 The CXM544 magnetometers are calibrated to read directly in Gauss Proper operation of these sensors is difficult to verify without elaborate calibration equipment However proper ballpark verification of operation can be accomplished by pointing each magnetometer sensor into and out of the earth s magnetic field For these orientations the magnetometer should read about 0
27. n text mode once 0x01 Send all data In Binary mode once 0x02 Send all data In IEEE mode once 0x10 Send all data in text mode a loop until AutoStart is not Ox5A Ox11 Send all data In Bin mode in a loop until AutoStart is not 0x5A 0x12 Send All Data In IEEE mode in a loop until AutoStart is not Ox5A 09 User power on baud rate lock if not Ox5A sensor will use 9600 Baud 10 User power on baud rate Use With Caution Crossbow Technology Inc Page 24 SUNSTAR O O http www sensor ic com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 163 con SUNSTAR O E O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Target Const Baud 10 75 37 150 36 300 35 600 34 11 Not Used 12 Lowest Calibration Temp in counts LSB 13 Lowest Calibration Temp in counts MSB Target Baud 1200 2400 4800 9600 Const 10 33 32 31 30 14 Distance in counts between Calibration Points LSB 15 Distance in counts between Calibration Points MSB 16 Number of Temp Points in the SEEROM 17 The Table Mag Offset Scale Value Offset TableOffset 2 lt Byte 18 gt 18 The Table Acc Offset Scale Value Offset TableOffset 2 Bytest19 19 The Table Mag Scale Scale Value Scale TableScale 24 lt Byte 20 gt 20 The Table Acc Scale Scale Value Scale TableScale 24 lt Byte 21 gt 2 The Table Mag Ortho Scale
28. nt repeatedly Crossbow Technology Inc Page 9 SUNSTAR O O http www sensor ic com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 163 con SUNSTAR O E O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 upon power up Byte 01 must be set equal to 5A for autosend mode to be active The format of the data sent in autosend mode is determined by the value of byte 08 For repetitive text transmissions set byte 08 10 For repetitive binary transmissions set byte 08 11 7 Descriptions of the System Internal Constants The CXM544 employs two types of internal constants 1 byte and 2 floating There are ap proximately 43 byte constants which are used to configure the operating characteristics of the CXM544 The most important of these constants and their functions follow Detailed descriptions of all the internal byte constants can be found in the Appendix of this manual z enables echoing when non zero enables autosend when 5A 02 enables sensor A D count output when 0 sensor output when 02 and angle output when 03 Sets power on mode e g 10 enables autosend in ASCII mode on power on N O Baud rate lock 5A if any baud rate other than 9600 is to be used 8 Changing the Baud Rate To change the communication baud rate from 9600 baud to any other rate you must first change byte constant 09 to 5A Then byte 10 can be se
29. nt the acceler ometer output in gees The temperature C follows the t header The above outputs represent data sent when the CXMS544 is in sensor mode If angular data is required the system mode will need to be changed In general the CXM544 operating characteris tics are controlled by the values of internal byte constants These constants are stored in the system EEROM and can be changed by a two step process The two step proc ess is used for security reasons to ensure that these constants are not inadvertently changed To change the CXM544 to angle mode byte 02 must be changed from 02 sensor mode to 03 angle mode Crossbow Technology Inc Page 8 SUNSTAR O O http www sensor ic com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 163 con SUNSTAR O E O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 To accomplish this type 01 CR The unit will respond with the message enabled Next type the sequence 0OWC02b03 lt CR gt 0 Write Constant 02 byte 03 The unit will respond by sending the message done Now request data by sending the sequence 0SD lt CR gt The response will look something like this MX 180 0 AX 6451 MY 90 3 AY 4056 MZ 185 6 AZ 1 0001 t 24 3 The numbers following MX MY and MZ represent the system roll inclination and azimuth The numbers following the AX AY and AZ represent the system magnetic
30. ssor and 7 channel 16 bit analog to digital converter Six channels are assigned to the magnetometer and accelerometer outputs One channel provides temperature data from an internal thermometer The functions performed by the system microprocessor and A to D subsystem are 1 conversion of the sensor analog outputs to digital form 2 calibration of the sensor scale offset and alignment factors for a temperature variation and 3 implementation of serial communications between the system and an external computer The CXM544 communicates with the outside world over one of two serial bi directional in terfaces which can be selected from either TTL or RS232 voltage levels An ASCII character command language has been created to facilitate communication with the CXM544 For in stance if the ASCII characters for 0 S and D are sent in sequence the CXM54A interprets this as a send data command and responds by sending over the serial interface an ASCII string representing the value of all magnetometer accelerometer and temperature outputs The leading zero in this sequence denotes the system serial number The CXM544 can also be configured to send angle data roll pitch and azimuth instead of the accelerometer and magnetometer sensor data An auto send data mode is included in the CXM544 software When this mode is active data is repeatedly sent after power is applied to the system at a rate of two transmissions per sec ond in angular output mode an
31. t according to the following table Constant 10 value After setting byte 10 turn the power to the CXM544 off and on to set the new baud rate Note When byte 09 is set to any value other than 5A the system baud rate is 9600 Crossbow Technology Inc Page 10 SUNSTAR O O http www sensor i c com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 63 con SUNSTAR O E O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 9 Verifying Proper Operation of the System Proper operation of the CXM544 can be verified when the system is in either angle mode byte 02203 or sensor mode byte 02202 In angle mode proper operation is verified by placing the CXM544 in known orientations and comparing the CXM544 measured data with the known orientation data To check roll and inclination outputs place the CXM544 on a known flat surface with the Z axis pointed down A flat surface can be set up and verified by using a bubble level Request data from the CXM544 and verify that the roll and inclination outputs are as follows roll 0 0 5 inclination 90 0 5 Next roll the CXM544 about the X axis in increments of 90 and verify that for each posi tion the roll angle increments in succession to 90 180 and 270 while the inclination angle remains 90 0 5 To verify inclination at 0 and 90 position the CXM544 so that the X axis is po
32. ter is oriented so the X axis arrow points north then the X axis output voltage will be positive If the X axis accelerometer arrow is pointed down the X axis accelerometer output will be positive Crossbow Technology Inc Page 4 SUNSTAR O O http www sensor ic com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 163 con SUNSTAR O0 O DD http wmwsersor ic com TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 o o o c E s 3 T E Bo 2 s 23 c 5 oo g x do o O Ew a oo co 1 o 8 LB Sf H e E E LO Ne 2 Ne A 6 S E 5 E o lt m lt 5 I E oz ala OO 5 aloe a 5 O iO K N Hep oloo o a Figure 1 Crossbow Technology Inc Page 5 SUNSTAR O O http ww sensor i c com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 3163 con SUNSTAR O O O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 4 Electrical Interface The electrical interface to the CXM544 system is shown in Figure 2 Seven flying leads 26 gauge Teflon insulated are used to make connection to the system The functions of the out put wires are shown in Figure 2 The CXM544 system can be powered either through an in ternal voltage regulator which converts the input voltage to the 5 volts for internal us
33. the correction mode is 0 the Mag and Acc data is in a two byte signed integer format in counts If the correction mode is 1 or 2 the Mag and Acc data is in a two byte signed integer format encoded as the float value times 10000 1 2345 12345 If the correction mode is 3 the data is angles and is represented in a two byte signed integer format encoded as the float value times 10 123 45 1234 The Temp data is in a two byte signed integer format encoded as the float value times 100 123 45 12345 lt 129 gt and lt 132 gt Sends All Data in IEEE Floating point format in the current format as se lected by Byte constant 2 If the correction mode is 0 1 or 2 the data is returned as lt lt lt lt Sent First lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt Sent Last lt lt lt lt If The Command is 129 NUM DATA BYTES gt lt MxX gt lt AX gt lt MY gt lt A Y gt lt MZ gt lt AZ gt lt MT gt lt AT gt lt 0 gt lt DATA CHECK SUM gt size 8b 32b 32b 32b 32b 32b 32b 32b 32b 8b 8b in bits If The Command is 132 NUM DATA BYTES gt lt Roll gt lt MRoll gt lt Pitch gt lt Mag gt lt Head gt lt Grav gt lt MT gt lt AT gt lt 0 gt lt DATA CHECK SUM size 8b 32b 32b 32b 32b 32b 32b 32b 32b 8b 8b in bits END Ox7FFF is unique in the data stream NUM DATA BYTES 16 Crossbow Technology
34. to microprocessor communications For this mode the voltage levels for a 0 and 1 are approximately ground and 5V In the idle or marking state the output level is 5V The RS232 protocol is used by using serial com ports RS232 voltage levels for a 0 and a 1 are approximately 5V and 45V In the idle or marking state the 5V level is output About 1 second after power up the CXM544 will send out a sign on message This can be observed with an oscilloscope as a series of transitions from 5 to OV TTL or 5V to 5V RS232 Since PC s use RS232 protocol they can be directly connected to a CXM544 employing this protocol PC s use either a 25 pin or a 9 pin D connector to implement their serial ports This connector is always a bulkhead male connector on the P C chassis The serial in serial out and ground connections for these connectors are as follows Crossbow Technology Inc Page 7 SUNSTAR O O http www sensor ic com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 163 con SUNSTAR O O O O http www sensor i c con TEL 0755 83376549 FAX 0755 83376182 E MN L szss20 3163 con CXM544 User s Manual Version 1 4 rum 25pm opm Connect the CXM544 serial output line to the computer in line and the CXM544 serial input line to the computer serial out line To communicate with the CXM544 a terminal program will have to be run on the P C The Windows HyperTerminal program will suffice for this Other suitable term
35. x axis on the horizontal plane Inclination is the angle that the x axis makes with the down direction and is 0 when the x axis is down and 90 when the x axis is horizontal Roll or gravity tool face is defined as the angle of counterclockwise rotation about the x axis looking in the positive x axis direction required to zero the y axis acceler ometer output and position the z axis accelerometer so that its output polarity is posi tive Magnetic roll is defined as the angle of counterclockwise rotation about the x axis looking in the positive x axis direction required to zero the y axis magnetometer output and position the z axis magnetometer so that its output polarity is negative Magnetic roll is useful in defining the CXM544 orientation when inclination is near vertical In this situation g and g are near zero and roll and azimuth calculations be come less accurate 10 3 Definitions The following sections describe equations for determining the CXM544 orientation angles These equations make use of the following definitions gx accelerometer x axis output gy accelerometer y axis output g accelerometer z axis output H magnetometer x axis output H magnetometer y axis output H magnetometer z axis output Crossbow Technology Inc Page 12 SUNSTAR O O http www sensor ic com TEL 0755 83376489 FAX 0755 83376182 E MN L szss20 163 con SUNSTAR O E OO http www sensor i c com TEL 0755 83376549 FAX 0755
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