CHIMU Datasheet and User Manual(OLDER
Contents
1. Om a CHIMU Micro AHRS User Manual CHIMU User Manual Rev D3 Table of Contents Contents ls INMOUCHON peer ence Ine eee etree er ee E ee ee iaopoa 4 1 1 it A te TEE 4 Ll lt lt 1 un opa 4 Ll2 Acceleration un UC 4 1 1 38 Magnetic field liMITS oocooccoocnconcconcconnconoconoconoconocononononononononononononanonanonanenanenanes 4 1 1 4 BIT and User Responsibility sese eee ee eee 4 1 2 Theory OF OD CT ANON ss 5 E WEE af OMG ION Sesso id o ias 5 1 2 2 Dynamic Operation Centripetal Acceleraton eee eee eee eee 6 1 3 Mod s f OPS e mercenaries iaa 6 2 Specifications and Charachersice sse eee eee 7 2 1 Performance Specifications see ee ee ee eee 7 2 2 Sege We nee 8 23 Absolute Maxim m Ratings iercesnccenteend necaneademeteendenonsaneaventiamouandi snc oani nakaka ania 8 2 4 Mechanical and Pin e ln 9 24 1 PP 9 2 4 2 Recommended Connectors sss see eee ee 9 2 4 3 Coordinate System and Orientation sss eee eee 10 244 D PP A A aaa a ias 11 3 Hardware Negral EE 12 3 1 ssi E nn E E osaeraeee toe eeaatiee 12 Sill MNO UCI OW CT EE 12 Sa ee el 12 3 2 Special IM SAGO Pl Suicidas rio cpediads 12 3 2 1 External Speed Select Pin 3 DOT 12 322 GOM Sell Kale E NGS adaptan 12 323 Sbecial Pn 11 RATE 0 esn r aE ENEE rer E RNS 13 324 DPecdl Pn 12 RATE E 13 3 2 5 Speed Indicator Pin 18 ANA Ter ee a a E Ea 13 3 2 6 Angle Rate Output Selection Pin 17 ANA 13 3 2 7 User Option Select Pin2. bit reversed version of the poly 0x04C11DB7 unsigned long UpdateCRC unsigned long CRC_acca unsigned char CRC_input unsigned char ii loop counter Create the CRC dividend for polynomial arithmetic binary arithmetic with no carries CRC_acc CRC_acc A CRC_inputs Divide the poly into the dividend using CRC XOR subtraction CRC_acc holds the remainder of each divide 77 Only complete this division for A bits since input is 1l byte for i 05 i lt 85 itt Check if the MSB is set if MSB is lu then the POLY can divide into the dividend if CRC_acc 8 0x00000001 0x00000001 if so shift the CRC values and XOR subtract the poly CRC_acc CRC_acc gt gt 15 CRC_acc a POLY5 de else d if nots just shift the CRC value CRC_acc CRC_acc gt gt 15 Return the final remainder CRC value return CRC_acci CHIMU User Manual Rev D3 16 5 Input Message Details Shown in this section are specific input message requirements and details 5 1 Input Message Device ID IS Required The unit shall not respond to requests that do not contain its device ID The default factory value for the device ID is 0x01 but can be changed by the user The broadcast device ID of O0xAA will force any units listening to accept the messages sent 5 2 Input Message Summary The output messages from the unit are shown in this summary table Table 3 CHIMU Message Input Name
3. WD Length Ping Dn D Communication check Bias and Scale Factor Sets bias and scale factor values 11 and 12 Calibration E ii De Calibration Calibration Configuration CLEAR Clears configuration flash memory Configuration SET Saves current configuration to flash memory Saves current rate sensor biases as power up defaults This is in addition to temperature calibration values for bias Attitude estimator selection quaternion or Euler default 1 quaternion Special integrates gyros only to check scale factor Gyro SF Check Allows input of vehicle velocity vector to account for centripetal acceleration Initialize Gyros 0x0C O Sets current value for rate sensors as zero point Gyro Bias Save Estimator Type Centripetal Velocity Device ID Change Sets new device ID Sets new magnetic reference vector and declination inclination for local area Performs a software reset of the unit Sets the output rate and message mask on the UART AE Sets options enabled by Pin 20 use Allows override in Euler estimator of internal yaw reference source Magnetic Reference OxOE Vector Reset OF UART Rate and Mask 0x10 Settings User Pin Option Select GPS Substitute 0x13 Heading J J 2 1 1 1 13 2 21 1 5 CHIMU User Manual Rev D3 5 2 1 PING ID 0x00 Message Header Length Device Package Checksum Structure ID OxAE OxAE 1 id or 0x00 None XSUM OxAA eS Byte offset Number
4. 3 2 3 Special Pin 11 RATEO This pin requires special external circuitry to be useful As a default this pin outputs current proportional to the current pitch attitude of the unit Direct rate output can be achieved via setup thru the serial port The output from this pin is NOT A VOLTAGE External interface boards that provide useable voltages from this pin are available Please contact us for more information before attempting to interface to this pin 3 2 4 Special Pin 12 RATE This pin requires special external circuitry to be useful The pin outputs current proportional to the current roll attitude of the unit Direct rate output can be achieved via setup thru the serial port The output from this pin is NOT A VOLTAGE External interface boards that provide useable voltages from this pin are available Please contact us for more information before attempting to interface to this pin 3 2 5 Speed Indicator Pin 18 ANA1 Described previously this pin when enabled by Pin 3 will accept a voltage in the range of 0 to 2 5V to represent a forward speed of 0 to 66 m s to allow centripetal corrections This pin may be interfaced with proper scaling directly to a pitot tube airspeed sensor output for example lf more complex velocities are present or if a hardware interface is not desired then software input of the vehicle velocity should be used For aircraft a forward speed indicator should be sufficient for mo
5. Device Package Checksum Structure ID This message appears on boot and at request via ping request input message It responds with and the byte values for the onboard software major and minor values CHIMU User Manual Rev D3 42 Een 6 2 2 IMU RAW ID 1 ID Message l ten y temp ADC counts O iO T raw counts 7 raw counts e T raw counts Li E raw counts e EE raw counts IEA FEO PO Ira O e raw counts A 11 counts TIET O Te counts e O E counts 20 Ue SPARED ANA ADC read CHIMU User Manual Rev D3 43 Em 6 2 3 IMU FP ID 2 Structure ID OxAE OxAE U1 XSUM Byte offset Number format R4 CPU Temp C Internal CPU temperature AR ACO mis Accel XO BR A ACY S Accel YO 19 A ACC ms ced Z WR 4 RATEX iade Gyro X 20 RA DATEN rps Gyro Y 24 Die DATEZ i rps Gyro ZZ 28 De MAGk Gauss Magnetic X 92 Die MAN Gauss Magnetic Y _ _ pee e ESTI eee ANAT ADO read o 7 ee gg 005 Time Time since turn on internal CPU timer CHIMU User Manual Rev D3 44 E 6 2 4 Attitude ID 3 IMPORTANT Estimator choice defines which set of data Euler Quaternion is valid Te Me E ID Message Structure OxAE OxAE U1 XSUM aren A Bree offset offset Sumber format __ format Roll angle es THETA Pitch angle 4 __ PSI rad Yaw angle Reported True North if reference vector has been applied else magnetic north Phi Dot rad s Roll angle rate identical to sca
6. Local magnetic een Er This data can and should be tailored for a specific location if accurate heading is desired Use the magnetic reference vector input message to change and save this information CHIMU User Manual Rev D3 59 6 2 13 RATE SENSOR SF CHECK ID 15 Message Header Length Device Package Checksum Structure ID OxAE OxAE U1 XSUM Byte offset Number format Integrated roll Roll rate sensor angle integrated from start of mode entry Integrated pitch Pitch rate sensor angle integrated from start of mode entry Integrated yaw Yaw rate sensor angle integrated from start of mode entry CHIMU User Manual Rev D3 96 7 Software Reprogramming The CHIMU board can be reprogrammed in the field if necessary A separate programming package must be used to successfully reprogram the unit and access to power ground and pins 22 and 23 are required Please contact us for more details CHIMU User Manual Rev D3 57 E 8 Appendix A Quaternion vs Euler Estimator For dynamic situations where 3D rotations are expected to occur rockets tumbling vehicles etc the quaternion estimator is the best choice Stable implementations that will not spend significant time pointed at 90 degree pitch orientation may use the Euler formulation as well In Quaternion mode the default only quaternion and quaternion rate outputs occur To transform these into standard Euler angles it is r
7. O O O O O O All units shown in inches 2 4 2 Recommended Connectors The connectors on the CHIMU have a 0 05 spacing Specifically the CHIMU pins are Digi Key part number S9014E 12 ND The recommended mate socket that custom designs should use to plug CHIMU into is Digi Key part number S9005E 12 ND For reference a picture of this connector is shown here CHIMU User Manual Rev D3 2 4 3 Coordinate System and Orientation Orientation shown X Y Z frame is the local body frame using standard aircraft axes The unit with applied axes coordinate frame is shown below X forward Y right It is assumed for the rest of this manual that this axis corresponds to a standard vehicle axis All rotations obey the right hand rule In this case the following terms are defined e Pitch rate angle 6 8 positive pitch rate is rotation about the Y axis from the Z towards the X axis e Roll rate angle positive roll rate is rotation about the X axis from the Y to the Z axis e Yaw rate angle Y Y positive rate is rotation in a clockwise direction about the Z axis from the X to the Y axis CHIMU User Manual Rev D3 k O 2 4 4 Pin Assignments Table 1 Pin Assignments UO Pin Description Connection Required for Typical Operation An AA rue SSS EI A 0 x o External Speed Sensor enable DIO 1 ground pin if external analog speed sensor available 4 ss OOOO R
8. during operation These are the result of magnetometer or accelerometer calibration inconsistencies that may not be noticeable to the user as well as inherent changes that can occur in the unit over time To obtain the very best operation i e minimal startup time at a certain operating temperature and environmental conditions we recommend the following 1 Perform the temperature calibration prior to this 2 Allow the unit to operate until steady state is achieved on the gyro bias estimates 3 Send message 0x08 Gyro Bias Save to the unit The bias values will be saved to flash memory and will be used on every power up after this These values can be cleared from flash if the desired biases change over time We do not recommend using this for most applications Most applications do not need this and saving these biases may not be the optimal settings for different usage of the unit CHIMU User Manual Rev D3 60 ES
9. n T 1 a COM Select Ss MOSI SPI Master Out Slave In UART com TO CHIMU emo DS UART com FROM CHIMU LZ a f x iia awe PI Master Slave Out DEE won NA OX RATEO eg compensated output of pitch axis rate or angle software selected default rate Special compensated output of roll axis rate or RATE1 angle software selected default rate AB NC M of gt us o Internal IFC Clock Do Not Connect ee ES e vk anas age r Rz aas aaa Tan g Angle or Rate mode output from pins ANA2 11 12 Leave unconnected for rate mode Connect to ground for angle mode X axis velocity input ER CO E DIO 2 User gt gt select pin SW version 1 4 and EE ee o2 GND O O NA K SN MIN IEEE AR T Leer RST C2CK O Soft reset active low reset holds CPU in reset 24 3 3V Out O Umied 3 3V supply 60mA max CHIMU User Manual Rev D3 1 EA 3 Hardware Integration Presented in this section are selected hardware interface comments to help ease integration of the unit in the end user system 3 1 Power 3 1 1 Input Power The CHIMU module operates off a nominal 3 3V input However up to 6 5V may be applied A higher voltage may result in more thermal dissipation on the board but this should not affect operation Do not exceed 6 5V or damage may result The system draws very little power typically it will require 30 mA of supply for operation More will be required if the output power pin is used If the 3 3V
10. requests a DAC offset message 1 writes the offsets until the next power cycle 2 commits them to flash memory i e permanent Counts for ADC 0 to 4095 offset to the Pitch channel Counts for ADC 0 to 4095 offset to the Roll channel CHIMU User Manual Rev D3 5 2 4 ACCELEROMETER CALIBRATION MODE ID 0x03 AAA Structure ID OxAE OxAE 1 id or 0x03 See Below XSUM AE AA EIN E TINE offset Number format U1 Position O level x y 0 z 1 1 u eo x y 0 z 1 2 e x 1 y 2 3 nose down x 1 y z 0 4 right wing up x 0 y 1 Z To start the calibration process the level 0 position must be sent first To finish the calibration the right wing ps 5 position must be sent last Recommended use if needed e Enter calibration with unit level command e Progress thru all 5 remaining positions sending required command at each position e Final position results in bias and scale factor being saved to flash memory Any position other than 5 may be sent during calibration and the new value shall be recorded in place of the last one Keep the unit motionless during the command to prevent erroneous acceleration from entering the calibration process CHIMU User Manual Rev D3 5 2 5 MAGNETOMETER CALIBRATION MODE ID 0x04 Structure ID OxAE OxAE 1 id or 0x04 See Below XSUM OxAA A A Byte offset Number format U1 Action O Enter magnetometer calibration mode 1 exit mod
11. 0x01 Persistent Bias and Scale Factor 0x04 Persistent 6 2 Output Messages The output messages from the unit are shown in this summary table Table 5 CHIMU Message Output Name e Q A length _ Description seen I m alive message with software version number IMURaw 1 22 Rawcountsfromsensorss _ MUER 2 48 Floating point values Oana E gana len apa quaternion or Euler output is prime Donner O E ll channels Mode BIT Indicates active mode Magnetometer Cal 6 12 Magnetometer calibration data Gyro Bias IT 12 Rate sensor biases calculated by estimator Temperature Cal Data 35 Output during temperature calibration ee data results DAC Offsets a IEA User Pin Select Reins WIS Ee RA RE settings for user pin select options Option RESERVED 11 13 Reserved for future messages Mag Ref Vector Current magnetic reference stored on unit Scale Factor Check Allows check of rate sensor scale factor CHIMU User Manual Rev D3 Note The length shown in this section is the package payload length for that message lt does not include the header characters OxAEAE length byte device ID byte message ID byte or checksum byte CHIMU User Manual Rev D3 41 a 6 2 1 PING ID 0 OxXAEO0XAE 9 UT pr Bee Below XSUM A U1 I m Alive 0x23 character E ea version identifier U1 SW Minor Minor software A linia Pp p T es Number serial number ge 33 Message Header Length
12. 11 This is a reserved factory message capability for the unit CHIMU User Manual Rev D3 5 2 19 USER PIN OPTION SET ID 0x12 A Message Header Length Device Package Checksum Structure ID OxAE OxAE id or 0x12 See Below XSUM OxAA AA AA A Option Select See below ICI A E EE EC E e I EA E EC E 2 Die Spare A 4 W C Read write 0x00 Read save to flash current settings via output Also Disable and message ID 10 clear pin flash settings 0x01 write completely settings and use pin until next power up 0x02 will write and save to flash 0x03 clears any settings from flash Option Select Value Function when Pin 20 is Function when Pin 20 is pulled low allowed to go high UART 1 is disabled and CHIMU UART 1 is enabled pins are changed to open drain pins Option Select This is useful when used with the Monkey unit for example and CHIMU com is handled via SPI bus ltfrees up the serial port on the Monkey platform for other functions None at this time None at this time CHIMU User Manual Rev D3 00 5 2 20 GPS Substituted Heading Replacement ID 0x13 Message Header Length Device Package Checksum Structure ID OxAE OxAE 5 id or 0x13 See Below XSUM OxAA A Byte offset Number format U1 Enable Disable 0x00 Do not use disabled 0x01 Use value i Ao RA GPS Heading This option is only valid when using the Euler estimator In high magnetic environments high
13. 20 DIO Bossa cicle 13 Io Ee Te UE ele OM EEN 13 SEAN A 13 Se OPIBUS acta ease cess pcs tte ce ott E point sueldo osado Seeing tec pte deals EE scales 14 3 4 Aa 14 Ae OTIS an ACS tii oa 15 4 1 Basie Message gd Det 15 ALI O la AA PPP 15 41 2 Number De d EE 15 SE O e A A A 16 Ds MputMessade Dela Secada delantal iaa 17 5 1 Input Message Device ID IS Required sees 17 5 2 inp t Message SUMMA cesaron epa ositas 17 Se TO CRL A a 18 5 2 2 BIAS AND SCALEFACTOR OO ebessen euer 19 SD A MODED OXO A 20 5 2 4 ACCELEROMETER CALIBRATION MODE ID Ox 32t 21 5 2 5 MAGNETOMETER CALIBRATION MODE ID Os 4 22 5 2 6 TEMPERATURE CALIBRATION MODE ID Ox Oft 23 CHIMU User Manual Rev D3 5 2 7 CONFIGURATION CLEAR ID OxO sss sese eee 24 5238 CONFIGURATION SET ID Ox OV ee 25 529 GYROBIAS SA VENIDOS EE 26 5210 ESTIMATOR TYPE SE EUR E estero pee 27 5 2 11 GYRO SCALE FACTOR CHECK ID OX0A occooccccccoccnccncconononcnconononcnnnconononcnconarononnnens 28 5 2 12 CENTRIPETAL VELOCITY INPUT ID OsOb 29 5 2 13 GYRO INITIALIZATION ID Oo 30 See WWE VIG ERAUS OKOD PA E E E EE 31 5 2 15 MAGNETIC REFERENCE VECTOR ID OXOE esse 32 3210 SOPTWARE RESET usa 34 5 2 17 UART SETTINGS ID 0X10 esas pontiac 35 S20 RE ERVED DOIT tarado terrano 37 5 2 19 USER PIN OPTION SET DOxi t 38 5 2 20 GPS Substituted Heading Replacement ID Oxvi2 39 6 uiputMessado RE EE 40 6 1 Fixed Message Output 40 6 2 O
14. CALE FACTOR CHECK ID 0x0A Tn AS Message Header Length Device Package Checksum Structure ID OxAE OxAE 1 id or Ox0A See Below XSUM OxAA a Byte offset GEES format SF Check start 0 Stop stop 1 Start When this command is sent as a start the unit begins doing a direct integration on all three rate sensors and reporting the resultant angle via message OxOF 15 A typical example of using this message is to engage the operation rotate the unit a fixed angular amount and then check that the integrated angle meets it within some tolerance Note that biases are not removed from the sensors before they are integrated it is left to the user to account for this if using this message CHIMU User Manual Rev D3 28 ES 5 2 12 CENTRIPETAL VELOCITY INPUT ID 0x0B Structure ID OxAA On Centripetal 0 All OFF configuration 1 HW Centripetal Enable 2 SW Centripetal Enable Vehicle X velocity Forward velocity Y velocity Z velocity A vehicles velocity while rotating i e a plane changing course with a rudder has a forward X velocity and a yaw rate can induce centripetal accelerations that must be compensated for in order to maintain an accurate attitude estimate The CHIMU allows an external X velocity input via a hardware analog channel That channel can be enabled via a secondary pin This message allows byte O 0x01 enabling of that channel without needing to pull that enable pin low In this case on
15. IL SINGULARITY MAG FAIL TIMER READY FAIL SATURATION RESTART FAIL 1 TRUE 0 FALSE These bits require some more discussion 1 Magnetic Saturation BIT If the magnetometers saturate this bit will be set It is cleared after one reporting message i e non latching BIT 2 Singularity BIT If a singularity condition in the attitude estimate occurs this bit will be set to indicate a degraded estimate may be being output 3 UART BIT H set there was a buffer overrun or improper message sent to the unit It is cleared after one reporting message i e non latching BIT 4 Calibration BIT If there is a failure to complete a calibration process that could leave bad results in flash memory this bit is set 5 Temperature Calibration Ready BIT Set when Temperature Calibration is in progress and if there are no results to allow temperature calibration yet If the temperature calibration process is started at too high a temperature to allow enough data points this bit will never clear If it does clear the temperature calibration was successful enough to establish new values into flash memory and the process can be stopped 6 Watchdog Timer Restart Indicates that the unit has had to recover from a locked condition and its watchdog timer was engaged to reset the unit This BIT is typically flagged on start CHIMU User Manual Rev D3 O as a power down of the system can erroneously set this bit Powered in run operatio
16. and can remove small initial rates within approximately 30 to 60 seconds However to minimize startup time the unit should be temperature calibrated This allows the unit to compute the expected biases based on temperature This can be done to the unit before shipping or can be performed by the user to a basic unit The calibration process consists of the very basic sequence that follows 1 Place the unit in a cool environment i e refrigerator or even freezer 2 Remove the unit from the environment and power it up 3 Using our control software or user software send the temperature calibration command a Once the calibration command is sent the unit MUST REMAIN ABSOLUTELY MOTIONLESS UNTIL CALIBRATION IS COMPLETE 4 Once the unit has reported at least 3 temperature snapshots the unit may be commanded to end calibration a Atleast 30 degrees of temperature change from start to finish should be experienced for best results b We also recommend that you allow the unit to heat up to at least nominal temperature but preferably the normal operational temperature or above for best results 5 The coefficients are saved to flash memory and are active from this point forward at startup For extremely accurate operation at a specific operating temperature please see the next appendix CHIMU User Manual Rev D3 99 ES 10 Appendix C Set Point Calibration Even with temperature calibration the unit will have to learn biases
17. application static low frequency g s more elusive vibration sinusoidal random or shock impulse random events that may not show full saturation of the accelerometers in data output but have affected the sensors internally and corrupted the values Continued acceleration above the limits or excessive vibration shock events can corrupt the computation of rate sensor biases leading to poor bias estimates and a corrupt attitude estimate 1 1 3 Magnetic field limits Saturation of the local magnetic field can result in a pervasive attitude estimate error as well Calibration of the unit in the final configuration will help prevent errors introduced by hard iron in the local area However induced magnetic fields from high current devices or high power RF circuitry can result in operational errors After a proper calibration no axis should exceed a 1 value 1 1 4 BIT and User Responsibility Automatic sensing of limits being exceeded is difficult However the CHIMU does have some internal capability to discern these conditions Magnetic sensor saturation is reported in the Built In Test BIT message Future software revisions may include an indication of saturation or other errors on other sensors No system is fool proot however and all correct use and planning for events in case of failure are the responsibility of the user CHIMU User Manual Rev D3 1 2 Theory of Operation The CHIMU is an integrated set of MEMS senso
18. as values in flash memory This is in addition to temperature calibration as it reflects biases added after in run operation Only save these values if the unit has been motionless for 10 minutes or more under relatively steady state temperature conditions for best results Please see the appendix for more information CHIMU User Manual Rev D3 26 5 2 10 ESTIMATOR TYPE SET ID 0x09 Message Header Length Device Package Checksum Structure ID OxAE OxAE 2 id or 0x09 See Below XSUM OxAA AA A Byte offset Number format U1 Estimator type 0 Euler estimator 1 Quaternion estimator This message allows the internal estimator type to be set This can be saved to flash for subsequent boots with the configuration set command 0x07 The differences between the two are shown below Estimator type Estimator Type LS gt A Quaternion e No singularity points in User must decode the attitude interpret quaternion determination output correctly for use Quaternion output can in external code be used directly in navigation and other rotation calculations Standard roll pitch yaw Subject to gimbal lock output easy to visualize singularity at 90 degrees pitch orientation Further information about quaternion versus Euler configuration and the technical background behind the two estimators can be found in Appendix A Quaternion vs Euler Estimator CHIMU User Manual Rev D3 Y 5 2 11 GYRO S
19. ask allows selective output of data 3 3 2 SPI Bus The SPI bus is configured as a master device The SPI bus outputs all data at the full 200Hz data rate Further details including C source code for interfacing to this bus and receiving data is avallable upon request from customers 3 4 Feedback LED There is one 1 informational LED on the unit This LED is for information only and is not necessary to view during operation The LED operation is as follows e Boot Initialize Solid on e Normal operation toggling of on off at 1 10 the UART interface output rate e Failed operation in use Solid on or solid off CHIMU User Manual Rev D3 14 as 4 Software Interface The CHIMU hardware com interfaces have been described already Details on software setup and communication are presented here 4 1 Basic Message Structure Input and Output messages from the unit are identical Both include header and checksum and other information to protect data integrity and allow easier decoding by the end user 4 1 1 Message format Both input and output messages have a defined structure that consists of the following e 2 header bytes OxAE OxAE e 1 Message length byte one byte representing the payload length only i e no header length device id message id or checksum included 1 Device ID byte useful when multiple units are used in a single application 1 Message ID byte xxx Data bytes varies with me
20. ctive set when hardware channel is being used for forward velocity input Represents status of hardware enable pin but can be prevented if configured to ignore this pin e SPI Enabled 0 false 1 true CHIMU User Manual Rev D3 N 6 2 5 Bias and Scale Factor ID 4 Structure ID OxAE OxAE 66 Ut NONE Byte offset Number format 12 Temp Sensor Sg ee O ecc in TTT TINT enor E A for each axis bias normalized Hardware analog er 1 read velocity EEO bias FRE EN CN a RA 3 ja X Y Z SF Lem Note 3 waste point values one er each axis NAAA A Moi O FAM oo 14 16 18 38 42 46 50 54 58 Rate Sensor SF Magnetometer SF Local gauss normalized Hardware analog Scale as needed 1 read velocity for external input SF hardware speed input This message is output during magnetometer calibration automatically and at request typically Boot values for the rate sensors in this message will typically be zero as it is output before calculation Therefore requesting this message after run mode has been entered is the best method for obtaining the full correct set of data if needed CHIMU User Manual Rev D3 48 6 2 6 Mode BIT ID 5 Message Header Length Device Package Checksum Structure ID OxAE 0xAE U1 XSUM Byte offset Number format U1 Mode Mode 0 INIT BOOT 1 RUNNING 2 ACC CAL 3 MAG CAL 4 SF CHECK 5 TEMP CAL SAI CS IO A T T descr
21. current ferrous metal etc the magnetometer solution may become corrupted or invalid This message allows the user to replace the yaw correction within the CHIMU filters that is typically performed using the magnetometers with GPS heading This input value represents the actual heading of the unit typically returned from a GPS unit as Course over Ground or similar An update is sent with the first field enable disable set to 1 The last value associated with a valid use value field is maintained until either a new update is provided or an update disabling the feature is sent Because of this high rate repetition of stale data is not needed Note that heading is in degrees not radians to make it easier to interface to other systems Do not send updates faster than 5 Hz CHIMU User Manual Rev D3 CLO 6 Output Message Details Shown in this section are the specific message descriptions for output messages from the unit 6 1 Fixed Message Output The current message set is fixed with respect to mode All messages for a given mode are output at a fixed rate default is 25 Hz unless altered by the UART settings mask The modes and messages in that mode are as follows Table 4 Default Messages Output Per Mode Mode Messages Single Message or Persistent Bias and Scale Factor 0x04 Single Scaled sensor values 0x02 Persistent Attitude 0x03 Persistent Gyro Bias 0x07 Persistent Raw values
22. e To start the calibration process the Enter 0 command must be sent The unit should be rotated continuously pointing every axis at the sl vector magnetic north for you location Exit the calibration process by sending a 1 in the payload Do not have high current or ferrous metal near the unit within 1 foot during calibration unless it is part of the normal operating condition CHIMU User Manual Rev D3 5 2 6 TEMPERATURE CALIBRATION MODE ID 0x05 Structure ID OxAE OxAE 1 id or 0x05 See Below XSUM ARE O AA AAA a A A Byte offset Number format U1 Action 0 Enter temp cal mode 1 exit mode To start the calibration process the Enter 0 command must be sent The unit should be kept completely motionless at a cooled id initially then allow the unit to slowly warm to a higher temperature At least 30 degrees of temperature change from start to finish should be experienced for best results Results are saved to flash memory automatically at the exit of the mode Please see the appendix for more information CHIMU User Manual Rev D3 5 2 7 CONFIGURATION CLEAR ID 0x06 Message Header Length Device Package Checksum Structure ID OxAE OxAE 1 id or 0x06 See Below XSUM OxAA Byte offset Number format U1 Action OxAB clears flash All other values have no effect CHIMU User Manual Rev D3 24 PEREA 5 2 8 CONFIGURATION SET ID 0x07 Structure ID OxAA A Byte offs
23. e 1 022 radians declination 0 2199 radians The reference vector can be derived from the inclination and declination or from the information above However the CHIMU requires a unit vector so the information above must be normalized For the example data above X 24156 84 sqrt 24156 84 2 5401 57 2 40531 612 0 5086 Likewise the entire reference vector would be 0 5086 0 1138 0 8534 CHIMU User Manual Rev D3 33 Een 5 2 16 SOFTWARE RESET ID Ox0F Message Header Length Device Package Checksum Structure ID OxAE OxAE 1 id or OxOF See Below XSUM OxAA Byte offset Number format U1 Reset If package OxAB the unit will perform a software reset All non flash saved settings will be cleared to defaults This message will force a soft reset of the unit CHIMU User Manual Rev D3 34 EE 9 2 17 UART SETTINGS ID 0x10 Structure ID Al AA A OxAA A Byte offset Number format Mask of bits for entire output message structure See below for more information 0x00 Clear all settings from flash 0x01 write settings until next power up OxAB will write and save to flash 100 Hz output rate is not supported at this time Future reserved The CHIMU UART baud rate is currently fixed at 115kbaud However the output rate and message selection can be changed to help users with integrating the unit into their system Message Mask All messages may be turned off if desir
24. e Specifications are subject to change at any time without notice 2 2 Electrical Characteristics _ Characteristics Conditions Min Typical Max Units Power Supply Voltage Vad Range Referenced to GND Average measured at 3 3V Time Time to first valid Power on to first message out data Bias settling time Static test step change condition e Specifications are subject to change at any time without notice 2 3 Absolute Maximum Ratings Parameter Rating Acceleration any axis 0 5 ms 20009 Unpowered 0 3V to 7V Output Short Circuit Duration TBD Any Pin to Common Operating Temperature Range 30 C to 85 C Storage Temperature Range 40 C to 125 C e Specifications are subject to change at any time without notice Stresses above those listed under the Absolute Maximum Ratings may cause permanent damage to the device This is a stress rating only functional operation of the device at or near these or any other conditions above those indicated in the operational section of this specification is not implied Exposure to absolute maximum rating conditions for extended periods of time may affect device reliability Drops onto hard surfaces can cause shocks of greater than 2000 g and can exceed the absolute maximum rating of the device Exercise care during handling to avoid damage CHIMU User Manual Rev D3 8 EX 2 4 Mechanical and Pin Assignments 2 4 1 Dimensions Z out 920000000 O O O O
25. e sales Ryan Mechatronics LLC reserves all rights to this document and the information contained herein Reproduction use or disclosure to third parties without express permission is strictly prohibited Copyright 2009 Ryan Mechatronics LLC CHIMU User Manual Rev D3 1 Introduction The CHIMU is a miniature low cost Attitude Heading Reference System AHRS AHRS units employ rate acceleration and magnetic sensing to provide a full inertial attitude and heading estimate even under stationary conditions The CHIMU is intended for use in motion sensing applications including but not limited to e UAVs AUVs UAS etc Robotics Sports training and analysis Education Rocket science 1 1 Limitations The unit like any IMU AHRS can be pushed beyond the limits of its ability to sense any of the measurements it needs to operate correctly The following list includes results that are known to occur if operation exceeds the limits listed later in this document 1 1 1 Rate limits Saturation of maximum rate in any axis for any amount of time will result in an incorrect attitude estimate The longer the saturation duration the more error will be present in the attitude determination The attitude estimate shall recover once saturation has stopped and the internal filter has time to reconverge on the correct solution 1 1 2 Acceleration limits Excessive acceleration can include acceleration above the rated levels in continuous
26. ecommended to use the following transformation pseudo code Sub Get_Euler_From_Quat amp v As EULER_STRUCT amp q As QUATERNION_STRUCT float x1 SQW1SQAX1SQY1Sqz nNoOrm 5 SQW q w q wi SQX q x q x5 Sqy q y q y1 sqz q z E q 25 norm sqrt sqw sqx sqy sqz 5 Normalize the quat q w q w norms q X q x norms q Yy q y norms q Z q z norms vephi atane e O x q w E q x q y x q z a l 2 E sqx sqy 5 If v phi lt 0 Then v phi v phi 2 xPI5 x 2 0 x q w x q Y q z E q x 5 Below needed in event normalization not done If x gt 1 0 x 1 05 If x lt 1 0 x 1 05 If q x x q y q z x q w O 5 L v theta 2 xatanel q x1 Q w 5 elseif q x E q y q z q w D 5 Then v theta 2 Xatan2d q X q w 5 jelset v theta asin x v psi atane e O x q w x q Z q X x q y 3 l 2 x sqy sqz 5 If v psi lt 0 Then v psi v psi 2 x PI 5 CHIMU User Manual Rev D3 08 E 9 Appendix B Temperature Calibration With no calibration the unit will snapshot the biases on the rate sensors at power up assuming that the unit is motionless so that accurate initial bias estimates can be used If the unit is not temperature calibrated however then any motion on the unit during power up will result in biases that will affect the solution usually very dramatically The CHIMU dynamic estimator is constantly estimating biases for the sensitive components
27. ed thru use of a message mask This mask enables or disables the ability of the unit to output certain messages The mask should typically only be used to turn output messages 0x01 0x02 0x03 0x07 on or off These are the messages output from the unit during normal operation The mask bits correspond to the output message id numbers So message 0x01 Raw Output is bit 1 message 0x02 is bit 2 etc The default is no mask all on or OXFFFF The mask to turn off message 0x01 is OxFFFD CHIMU User Manual Rev D3 dl The mask to turn off message 0x01 0x02 and 0x07 is OxFF 9 UART Recommendations The maximum rate on the UART bus is 50Hz At 50HZ it is recommended that a mask be applied to turn off all messages except the Attitude 0x03 message to reduce data processing by the host processor The Attitude message contains attitude information as well as attitude rate information which typically necessary for control of a vehicle For 200 Hz data output implement the SPI bus UART Method for Low Rate Queries If polling only approach to using the unit is to be taken the user should set the update rate to the maximum 50Hz rate and use the Ping command to request individual messages In this case the CHIMU will respond within 20 milliseconds to a received request This method is not recommended for high rate data output CHIMU User Manual Rev D3 36 E 9 2 18 RESERVED ID 0x11 A Do not send message ID 0x
28. et Number format U1 Action OxAB saves to flash memory for Subsequent use All other values have no effect in this field Bit field settings See bit settings and meanings below This message allows certain configuration settings to be set and saved to flash if required The configuration settings can be set without saving to flash also to test the settings Flash save will only occur if OXxAB is written as the first byte in the payload The bits in the configuration status that can be altered directly in the second package byte are as follows Allow Rate Temperature Hardware SPI Enable Hardware Angle Out Calibration Centripetal Override Pin Config Configuration Start Stop Velocity default 1 Override default 1 default 0 Enable enabled default 1 rate out do not use default 1 allow enabled Note that the current estimator type bit 4 cannot be altered by this message However if this message is saved to flash then the current estimator type will be saved as well In this manner the default estimator that runs on power up may be changed Message 0x09 should be used to change the estimator type CHIMU User Manual Rev D3 O1 5 2 9 GYRO BIAS SAVE ID 0x08 Message Header Length Device Package Checksum Structure ID OxAE OxAE 1 id or 0x08 See Below XSUM OxAA a AA U1 Clear Save O clear 1 save current values to flash This message allows the setting or clearing of rate sensor bi
29. ev D3 31 Em 5 2 15 MAGNETIC REFERENCE VECTOR ID 0x0E Structure ID OxAA AA A Byte offset Number format X1 Read write O Request a save read message Ox0E 14 output 1 Write new vector 2 Write and save new vector to flash Ref Vector X Unit vector Magnetic component reference UNIT direction A A a E component ee o component A A gt a of magnetic field HE Tee F of magnetic field In order for accurate heading information to be developed the local magnetic field needs to be input into the unit To find local inclination and declination values for your area use your zip code or lat long at this site http www ngdc noaa gov geomagmodels IGRF jsp Have the site compute your local values and you will see a message similar to this Compute Magnetic Field Values Results will appear below gt Results for date 2009 6437 98828125 Declination 12 604 changing by 0 09 fyear Inclination 58 5879 changing by 0 004 year X component 24 156 84 changing by 27 01 n7 year Y component 5 401 57 changing by 45 68 nT year Z component 40 531 6 changing by 65 36 nT year Horizontal Intensity 24 753 38 changing by 36 3 nT vear Total Intensity 47 492 53 changing by 74 7 nT year CHIMU User Manual Rev D3 N However the inclination and declination must be changed to radians before inputting to the unit multiply them by Pl 180 For the example data above the inclination would b
30. format U1 Requested Requests a Message specific output message This message forces a ping output message 0x00 and a BIT message 0x05 as a response regardless of the package data The message indicated by the package byte other than 0x00 or 0x05 will be output as well CHIMU User Manual Rev D3 18 IES 5 2 2 BIAS AND SCALEFACTOR ID 0x01 Structure ID OxAA Byte offset Number format U1 Read Write Requests a read or specifies a write of data oa Sensor SR E not change oa Accel X Y Z bias a Note 3 integers KEN for each axis 9 1019 Re Rate Sensor bias Rad s VM A T T A bias normalized E analog EEE o Sensor SF Temp Sensor SF Bas 31 35 Accel X Y Z SF 599 Maes 3 floating point values one A each axis 39 43 47 B4 Rate Sensor SE _Rate Sensor SF alta SF Local gauss normalized R4 bet analog NEE as needed 1 read velocity for external input SF hardware speed input Typically these settings are not altered via this message Calibration of the unit stores these values automatically However advanced users may wish to save configurations and write them for experimental reasons CHIMU User Manual Rev D3 19 Em 5 2 3 DAC MODE ID 0x02 Structure ID OxAE OxAE id or 0x02 See Below XSUM OXAA A A Byte offset Number format CT 8 Read write save Offset channel 0 Offset channel 1 1 angle output from DAC channels 0 angle output 0
31. iption below The BIT message can be decoded per Message 3 as they are identical CHIMU User Manual Rev D3 49 E 6 2 7 MAG CAL ID 6 Structure ID OxAE OxAE U1 6 See Below XSUM AS Byte offset Number format 12 MagXmin gauss Min x axis magnetic value during cal 12 MagYmin gauss Min y axis magnetic value during cal 12 MagZmin gauss Min z axis magnetic value during cal 12 MagXmax gauss Max x axis magnetic value during cal 12 MagYmax gauss Max y axis magnetic value during cal 12 MagZmax gauss Max z axis magnetic value during cal This message shows the current magnetometer raw values during a magnetometer calibration It can be useful to display these values during calibration to highlight sensitive magnetic north calibration CHIMU User Manual Rev D3 90 EE 6 2 8 GYRO BIASES ID 7 Message Header Length Device Package Checksum Structure ID OxAE OxAE U1 XSUM EE Te Byte offset Number format R4 Rate X bias rad s X gyro bias calculated from internal estimator R4 Rate Y bias rad s Y gyro bias calculated from internal estimator R4 Rate Z bias rad s Z gyro bias calculated from internal estimator CHIMU User Manual Rev D3 91 E 6 2 9 TEMPERATURE CALIBRATON DATA ID 8 Message Header Length Device Package Checksum Structure ID OxAE OxAE U1 8 See Below XSUM Byte offset Number format l2 Bias Bias for x y z rate sensors based on temperature calibra
32. led sensor value bie Thea Dat radis Pitchanglerate ANT AA Ala scalar BRA A Quateionx a 30 4 gie Quatemionz R4 dot Rotation rate EEE ee See below for breakdown of calibration status byte 57 X1 Built In Test BIT See below for status byte o gt SC breakdown of Config Info status byte CHIMU User Manual Rev D3 45 Ken The calibration status byte is a bit field reflecting the state of the unit s internal calibration Shown below is the interpretation of this byte Calibration Status bit fields X Custom Gyro Bias DAC Magnetic Temperature Magnetometers Accelerometers UART Saved offsets set reference calibrated calibrated calibrated information rate sensors set 1 TRUE 0 FALSE Description of the bits is self explanatory by their titles except for bit 6 This bit indicates special UART settings have been saved to flash memory For basic operation magnetometers and accelerometers must be calibrated For precise operation magnetic reference information must also be set For faster startup and temperature insensitive operation the temperature calibration bit needs to be completed The DAC offsets are an added feature and do not affect estimate operation The built in test BIT status byte is a bit field reflecting the error state of the unit Shown below is the interpretation of this byte _BIT Status bit fields bit 7 A DC BUS WATCHDOG TEMP CAL CAL FAIL UART FA
33. ly the external ADC read will be used and it is assumed to represent the forward X velocity This message also allows byte O 0x02 a full velocity vector input to use including X Y and Z velocity vectors Warning The last velocity sent stays active until changed or this capability is turned off Make sure that constant updates are provided if using this function or that it is disabled in low velocity or near static conditions or erroneous attitude estimates will result CHIMU User Manual Rev D3 do 9 2 13 GYRO INITIALIZATION ID 0x0C AA Structure ID RA ee Te OxAA A ee Byte offset Number format There is no payload for this message When sent the current rate sensor readings are used as the new zero rate points overriding the current biases If a unit has been temperature calibrated this message will overwrite those values If a unit has not then this action occurs at boot The unit should be static during this event or a false zero set point will be set CHIMU User Manual Rev D3 30 Ee 5 2 14 DEVICE ID ID 0x0D A Structure ID OxAA AAA Byte offset Number format DD Dees Desired device ID U1 Save No Save 1 save to flash 0 do not save This message changes the device ID to the specified value If unsure of current device ID use OxAA If using on a network with multiple units be careful OxAA as device ID will change all units to the new ID CHIMU User Manual R
34. n of the unit should not see this bit flagged Check all inputs if it is flagged after startup 7 12C BUS Fail The internal 12C bus can get locked by devices on the chip under some circumstances In most situations the bus is cleared and reset in less than 50 milliseconds If this occurs however this bit is set to indicate the problem The configuration information status byte is a bit field reflecting the configuration state of the unit Shown below is the interpretation of this byte Configuration Info Status bit fields Allow SW Estimator Rate Angle Out Temp calibration HW SPI Hardware Centripetal Type Configuration active Centripetal Enabled Pin Config Velocity Velocity Override Active Active 1 TRUE 0 FALSE These bits require some more discussion e Hardware Pin Configuration Override If this bit is set default then the hardware pins for centripetal velocity temperature calibration and SPI enabling are active The configuration can be changed by the status of these pins at boot This can be disabled thru use of the configuration set message e SW Centripetal Velocity Active set when software velocity messages are being sent and used e Estimator type O Euler estimator 1 Quaternion estimator e TBD bit is reserved for future use e Rate Angle out 0 angle output on DAC channels 1 rate output on DAC channels e Temp calibration active O false 1 true e HW Centripetal Velocity A
35. orth if magnetic reference vector has been applied else magnetic north is reported General text cleanup 3 4 10 Output Message 2 floating point data had incorrect sequence of values Previous manual showed accel mags then rate Actual software has always been accel rate mags Documentation updated only 3 8 10 Pin 17 and 18 were incorrectly swapped in the documentation Pin 17 was incorrectly called out as the analog input Pin 18 is the analog input pin for speed if using that for centripetal calculations vs software messages Fixed in this revision documentation change onl IMPORTANT DISCLAIMERS This document and the use of any information contained therein is subject to the acceptance of the Ryan Mechatronics terms and conditions They can be downloaded from www ryanmechatronics com Ryan Mechatronics LLC makes no warranties based on the accuracy or completeness of the contents of this document and reserves the right to make changes to specifications and product descriptions at any time without notice Ryan Mechatronics LLC assumes no liability for damages or otherwise due to use of the information in this document or application of any device described in this document Ryan Mechatronics LLC stresses end user compliance with all applicable laws and regulations when using devices of this nature Use by an end user in violation of any applicable laws is automatic basis for termination of warranty technical support and futur
36. output pin is used to power external devices then the input power current will need to be increased to support this additional use 3 1 2 Output Power The module outputs 3 3V from its onboard regulator on pin 24 This is not intended to be used to drive any high current or critical loads but may be useful for pull up down or LED operation Total current from this output should be limited to less than 50mA More than this risks interfering with operation of the unit 3 2 Special Interface Pins The CHIMU utilizes external pins to help configure the unit if software interfacing is not possible These pins are described here 3 2 1 External Speed Select Pin 3 DIO_1 Pin 3 indicates to the unit that the external voltage on Pin 18 ANA1 should be treated as the forward X velocity indicator e High not connected o No external hardware speed input o DONOT EXCEED 3 3 VOLTS ON THIS PIN e Low Grounded o Pin 18 ANA1 acts as a direct indicator of forward X velocity according to the bias and scale factor associated with this input o Scale ranges from 0 to 2 5V o Standard bias and scale factor result in a linear scale of OV 0m s 2 5V 66 m s 147 mph 3 2 2 Com Select Pin 4 NSS Pin 4 indicates to the unit which communication structure should be used Currently SPI communication is only as a master device This pin is reserved for future use in an SPI slave configuration CHIMU User Manual Rev D3 12 Een
37. pin that allows input of forward speed as an analog voltage The second requires a full 3 axis velocity message to be provided to the unit via the serial port or SPI port External computation of velocity can be provided by airspeed sensors or a GPS unit typically 1 3 Modes of Operation The CHIMU has been designed to be simple and effective at providing attitude and heading information with minimal or no user intervention However there are some modes for calibration that likely will be used Below is a top level description of the typical operating modes for the unit This diagram may be useful in understanding the software commands to the module found in this section CHIMU User Manual Rev D3 2 Specifications and Characteristics Presented in this section are the sensor and system specifications for the CHIMU All parameters specified are VDD 3 0 V and Ta 25 C 2 1 Performance Specifications _ Characteristics Conditions Min Typical Max Units Attitude and Heading steady state E o E Range O to 360 R Accuracy 1 RMS Resolution 0 0004 R E E Range 90 R Accuracy 1 RMS Resolution 0 0004 R E B 8 Range O to 360 R Accuracy 1 RMS Resolution 0 0004 S Angular Rate we R Yaw 150 mese e A Yaw 0 04 DT ie Yaw 200 mom o em D EP Yaw lt 0 07 sec Acceleration Range Z Bandwidth Resolution All Magnetic Flux O Co a UE on a E Resolution All
38. rs that are managed via an onboard CPU to provide attitude and heading information along with raw sensor data and other useful information A top level flow of the primary components are shown in this figure 1 2 1 Startup Conditions The most difficult operation for a MEMS based IMU to perform occurs at turn on In order to provide a fast reliable estimate of attitude some systems require the unit to be held motionless during turn on This is to provide a zero for immediate calibration The CHIMU does not require this turn on requirement if it has been calibrated over temperature Static calibration values across the operating temperature range are preprogrammed prior to delivery or are calibrated recalibrated after delivery if necessary In run biases for the unit sensors are calculated as part of the internal processing after turn on and compensate for minor changes that may have occurred over time from factory defaults and operational conditions CHIMU User Manual Rev D3 1 2 2 Dynamic Operation Centripetal Acceleration Operation of an IMU in a dynamic platform like an airplane can lead to incorrect attitude computations unless centripetal accelerations are accounted for Many low cost MEMs based IMUs do not address this The CHIMU allows two methods for compensation of centripetal accelerations Both require an external input of vehicle velocity The first and most useful for many applications is an external
39. ssage 1 Checksum byte The checksum byte is the LSB of a 32 bit CRC checksum calculated for the entire message including header bytes length id and data bytes Details and code for calculating this checksum are provided later in this section 4 1 2 Number Formats Much of the data messages use single bytes and unsigned integers which are typically easy to understand A number format list is presented here for clarity on number formats however All multi byte values are ordered in Big Endian format unless otherwise indicated NOTE Most PC s Intel are Little Endian oriented This needs to be taken into consideration if interfacing directly to the device with custom software All floating point values are transmitted in IEEE 54 single precision Table 2 Number Formats Abbreviation Type Size Comment Min Max lanai TE oneg et Ui Unsignedchar il D 288 DH Signedchar Za complement 128 127 0 De ll D8 e 0 65535 S 32768 32767 Bitfield 2 HA 0 4 294 967 295 2 147 483 647 1 2M27 2M27 E IEEE 754 Single Precision ASCII encoded i D R S TT a EC CHIMU User Manual Rev D3 nik O1 4 1 3 CRC Checksum Code The checksum calculated for outgoing messages is a 32 bit CRC code C code to compute the entire checksum is shown below Important notes 1 Only the LSB of this CRC is appended to output message 2 The starting polynomial is OxXFFFFFFFF define POLY OxEDB88320
40. st applications 3 2 6 Angle Rate Output Selection Pin 17 ANA2 This pin when left high allows scaled and corrected rate outputs from pins 11 and 12 If this pin is grounded then the angle output mode for these pins will be selected Currently if the angle output mode is selected then the Euler estimator will engage automatically to ensure angle output is compatible with expected definitions 3 2 7 User Option Select Pin 20 DIO_2 Enabled in SW version 1 4 and higher this pin activates different features on the CHIMU unit when pulled low Those features are enabled via a special software message The default activity on this pin is nothing i e no effect e Custom designs should provide a breakout for this pin in case future functions prove useful 3 3 Communication The CHIMU has two means of communication a standard UART and an SPI port 3 3 1 UART The UART is a 3 3V level interface The unit does not use hardware handshaking It is always 8 bits no parity and one stop bit 8 N 1 Do NOT interface with a standard RS 232 port as the CHIMU User Manual Rev D3 k Go voltages on that port will damage the unit An external adapter that uses 3 3V to convert to RS 232 levels can be powered from the onboard 3 3V regulator Standard operation is at 115k baud with a message output rate of 25Hz Currently this is a fixed Daud rate However the data output rate can be varied from 0 to 50Hz and a message m
41. tion routine in effect Scale Factor Scale factor for same Correlation Figure of merit for Coefficient correlation of temperature calibration per channel Temperature Current temperature Data Points Number of temperature points included in calibration the more the better Temperature calibration is done prior to shipment If you need more from this function contact us prior to performing please CHIMU User Manual Rev D3 92 ES 6 2 10 DAC OFFSET READ ID 9 Message Header Length Device Package Checksum Structure ID OxAE OxAE U1 9 See Below XSUM Byte offset GU format T aa rx channel 0 ir OO eer Fr channel 1 DAC offsets are values loaded by the user to modify the output from the DAC channels in rate and angle output modes Default should be zero for each channel CHIMU User Manual Rev D3 99 ES 6 2 11 USER PIN OPTIONS READ ID 10 Message Header Length Device Package Checksum Structure ID OxAE OxAE 8 Ut XSUM AAA Byte offset Number format U1 Function select 0x00 Disabled nothing 0x01 Disable UART pins I Spare e e A HI Spare O So Spare H EC Spare SI et Faclo use only BO A Factory use only TI Ae Faclo use only CHIMU User Manual Rev D3 94 E 6 2 12 MAGNETIC REFERENCE VECTOR ID 14 Message Header Length Device Package Checksum Structure ID 0 4 8 R4 3 Mag Es Unit vector magnetic field e e E declination R4 Inclination rad
42. utput e E 40 A A A 42 Be2 AIT TO Diosa totes 43 OAS A A a e ez E E 44 024A A 45 6 2 5 Bas and Scale Factor ID Ai 48 62 6 Mode BID arcas deg 49 627 MAGCAL ID 6 nadia 50 2 GROBA SE ID E 51 6 29 TEMPERATURE CALIBRATON DATA ID Sessa 52 E DEE Eege 53 6 2 11 USER PIN OPTIONS READ ODm0i 54 6 2 12 MAGNETIC REFERENCE VECTOR ID 14 ocooocccccnncnnconcnicnoccncconanoncnnanononnnnononanos 55 6213 RATE SENSOR SF CHEGK ID 15 session dalccioa ideas 56 Fo ene ReprograimnMiN Le EE 57 8 Appendix A Quaternion vs Euler Eetmaior sese eee ee eee 58 9 Appendix B Temperature CGalbraton css eee eee 59 10 Appendix C Set Point CGaltbaraton sse eee eee eee 60 CHIMU User Manual Rev D3 Release Notes Title CHIMU o o Subtitle CHIMU User Manual Type Manual Document number UM1000 o Revision Index______Date________ Name Status Comments LEE Kee E 10 2009 Updated temperature and bias calibration save appendices 12 9 09 Updated CRC information start value added Updated mechanical drawing to show space between pin rows 12 28 09 SW Version 1 4 additions include Temperature calibration made more robust Euler angles are now output at 20 Hz update rate even if quaternion estimator is selected Added user pin select message input 0x12 and output Ox0A Added substitute GPS heading use message 0x13 to replace magnetometer corrections in high magnetic environments Noted Yaw angle reported is True N
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