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V2Xe User Manual 

– May 2012 

Page 16 

kSetCalData (frame ID 0x0E) 

This  frame  writes  calibration  data  into  the  V2Xe  using  the  same  frame  structure  as 

kCalDataResp.    This  is  an optional  command  and  is  not  used for most applications.  

However,  it  allows  the  user  to  store  multiple  sets  of  calibration  coefficients  on  the 

host  system,  and  write  them  into  the  V2Xe  when  appropriate.    For  example,  if  the 

host  system  has  a  motor  that  sometimes  is  off  and  sometimes  on,  then  one  set  of 

calibration coefficients  can be  generated  and stored in  the host system  for when the 

motor is on, and a second set for when the motor is off.  The first set of calibration 

coefficients would be written to the V2Xe whenever taking a reading with the motor 

on, and the second set whenever the motor is off. 

5.6 

Making Measurements 

To make a measurement, it is first necessary to establish what data is to be output by sending 

the kSetDataComponents frame.  The kGetData command is sent to initiate a measurement, 

and the response will be the kGetDataResp frame which will contain the measured data, as 

established by kSetDataComponents. 

kSetDataComponents (frame ID 0x03) 

This frame defines what data is output when kGetData is sent.  Table 5-4 summarizes 

the various data components and more detail follows this table.  The first byte of the 

payload  indicates  the  number  of  data  components  followed  by  the  data  component 

IDs. 

 

Example:

  To query for heading and magnitude, the payload should contain: 

 

Note that the sequence of the data components defined by kSetDataComponents will 

match the output sequence of kGetDataResp. 

0x02 

Heading ID 

0x05 

ID Count 

Payload 

0x06 

Magnitude ID 

 

ID Count 

UInt8 

ID 1 

UInt8 

Payload 

ID 2 

ID 3 

UInt8 

 

UInt8 

 

………. 

Содержание CompassPoint V2Xe

Страница 1: ...User Manual CompassPoint V2Xe Electronic 2 Axis Compass Module...

Страница 2: ...ting 6 4 3 SPI Hardware Protocol 6 5 OPERATION WITH V2XE PROTOCOL 8 5 1 Datagram Structure 8 5 2 Parameter Formats 9 5 3 Commands Communication Frames 11 5 4 Module Set Up 11 5 5 Calibration 14 5 6 Ma...

Страница 3: ...LITY If any Product furnished hereunder fails to conform to the above warranty OEM s sole and exclusive remedy and PNI s sole and exclusive liability will be at PNI s option to repair replace or credi...

Страница 4: ...nse required to build a 2 axis digital compass from scratch Features include an onboard microprocessor for true plug and play compassing and magnetic field sensing a SPI interface 3 V operation softwa...

Страница 5: ...C per the guidelines in this manual these maximum ratings will not be violated Table 3 2 Module Characteristics1 Parameter Minimum Maximum Typical Supply Voltage VDD 3 0 VDC Idle Current 2 0 2 mA Cont...

Страница 6: ...nt range the gain and resolution can be increased by a factor of 2 by setting the ASIC period select to 4096 When setting higher selects be aware that the ASIC counter can overflow if the field is str...

Страница 7: ...ronization with the host Synchronization issues primarily occur during power up when I O and hardware are initialized This may cause glitches in the clock line which can be interpreted by the V2Xe as...

Страница 8: ...ic distortion contributors in a host system Place the compass in a fixed position then move or energize suspect components while observing the output to determine when they are an influence 4 3 SPI Ha...

Страница 9: ...he host keeps clocking the SPI interface after the V2Xe has completed sending a response the V2Xe will keep sending 0x00 for each byte clocked out In effect the connection is made to act like a half d...

Страница 10: ...s a variable length message depending on the number of parameters Example the command for kSetDataComponents with parameters kHeading and kMagnitude is specified below Sync Flag 0xAA Byte 1 Frame Type...

Страница 11: ...4 bytes are in reverse order LSB first Exponent S Mantissa 3130 2322 0 The value v is determined as if and only if 0 Exponent 255 v 1 S 2 Exponent 127 1 Mantissa Zero is represented by 4 bytes of zero...

Страница 12: ...rs are unsigned 32 bit numbers msb 31 24 23 16 15 8 lsb 7 0 Big Endian lsb 7 0 15 8 23 16 msb 31 24 Little Endian Unsigned 16 Bit Integer UInt16 UInt16 based parameters are unsigned 16 bit numbers Big...

Страница 13: ...esponse to kGetConfig 0x09 kSave Saves the current internal configuration and any new user calibration coefficients to non volatile memory Calibration 0x0A kStartCal Commands the V2Xe to start user ca...

Страница 14: ...y the kSave command must be issued Example To configure the declination the payload would look like Table 5 2 Configuration Identifiers Parameter Config ID Format Values Range Default kDeclination 0x0...

Страница 15: ...heading query command is received from the host If kSampleFreq is set to 0 Hz then X and Y counts are sampled and the heading calculated after a query is received kPeriod Config ID 0x05 This sets the...

Страница 16: ...save internal configurations and user calibration to non volatile memory Internal configurations and user calibration are restored on power up The frame has no payload This is the ONLY command that c...

Страница 17: ...valid samples the reported heading will be 1 00 degree kStartCal frame ID 0x0A This frame commands the module to start a user field calibration The calibration sampling frequency is set with the kCal...

Страница 18: ...whenever the motor is off 5 6 Making Measurements To make a measurement it is first necessary to establish what data is to be output by sending the kSetDataComponents frame The kGetData command is sen...

Страница 19: ...the raw values Their values are used to calculate the heading kHeading Component ID 5d Provides compass heading calculated from kXCal and kYCal where the heading range is 0 0 to 359 9 kHeading will e...

Страница 20: ...for 0xAA Sync Flag If True push data out If False loop on delay kGetDataResp frame ID 0x05 The response to kGetData is kGetDataResp The specific data fields that will be output ID 1 Value ID 1 etc sho...

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