User Manual CompassPoint V2Xe Electronic 2-Axis Compass Module
Table of Contents 1 COPYRIGHT & WARRANTY INFORMATION ................................................. 1 2 INTRODUCTION ......................................................................................... 2 3 SPECIFICATIONS ......................................................................................... 3 3.1 Performance Specifications .................................................................. 3 3.2 Package Information ...................................................................
1 Copyright & Warranty Information © Copyright PNI Sensor Corporation 2012 All Rights Reserved. Reproduction, adaptation, or translation without prior written permission is prohibited, except as allowed under copyright laws. Revised May 2012. For most recent version visit our website at www.pnicorp.com PNI Sensor Corporation 133 Aviation Blvd, Suite 101 Santa Rosa, CA 95403, USA Tel: (707) 566-2260 Fax: (707) 566-2261 Warranty and Limitation of Liability.
2 Introduction Thank you for purchasing PNI Sensor Corporation’s CompassPoint V2Xe (pn 11862). This RoHS-compliant, low-power-consumption, 2-axis compass module, provides all-digital compass heading outputs accurate to 1°. The V2Xe provides low power consumption, a small footprint, large signal noise immunity under all conditions, and a large magnetic field dynamic range. And measurement data is very stable over temperature and inherently free from offset drift.
3 Specifications 3.1 Performance Specifications Table 3-1: Absolute Maximum Ratings Parameter Minimum Maximum Units -0.3 4.1 VDC Input Pin Voltage (VIN) VDD – 0.3 VDD + 0.3 VDC Input Pin Current (IIN) -2.0 +2.0 mA Storage Temperature -40 +85 C DC Supply Voltage (VDD) CAUTION: Stresses beyond those listed above may cause permanent damage to the device. These are stress ratings only.
Footnotes: 1. Characteristics are subject to change. Values assume supply voltage of 3 VDC. 2. Measurement taken with no sensor activity 3. Measurement taken during continuous polling of sensors 4. Field measurement range is defined a the monotonic region of the output characteristic curve 5. Gain is defined as the change in the number of counts from the ASIC when the period select is set to 2048, per change in the magnetic field in µT.
4 Set-Up 4.1 Electrical Connections The V2Xe incorporates two 7-pin SIP connectors. The pin-out is given below in Table 4-1, where pin #1 and pin #14 are defined in the mechanical drawing (Figure 3-1). Table 4-1: Pin Descriptions Pin # Pin Name Description 1 SCLK Serial Clock input for SPI port 2 MISO Master In, Slave Out for the Module SPI port 3 MOSI Master Out, Slave In for the Module SPI port 4 SSN Slave Select for the V2Xe’s SPI port.
4.2 4.2.1 Mechanical Installation Mounting Orientation The V2Xe should be mounted horizontally and as level as possible. The arrow on the top of the board should point in the direction of travel or line of sight. 4.2.2 Locate away from changing magnetic fields It is not possible to calibrate for changing magnetic anomalies.
SSN *Tri-state when SSN is HIGH. Figure 4-1: Transfer from Host to V2Xe SSN *Transmit zero-byte (recommended) **Tri-state when SSN is HIGH. Figure 4-2: Transfer from V2Xe to Host The nature of the SPI interface is such that the host receives the bytes synchronously while sending bytes. Therefore the V2Xe will send a byte containing 0x00 for every byte received. The V2Xe itself will ignore any bytes received while it is sending a response.
5 Operation with V2Xe Protocol The following section describes the data structure and the commands used to communicate with the V2Xe over its SPI interface. 5.1 Datagram Structure The datagram structure for a basic message is given below: Sync Flag 0xAA Frame Type 0xXX Terminator 0x00 Byte 1 Byte 2 Byte 3 Example: the command for kStartCal would be as specified below.
5.2 Parameter Formats Note: Floating-point based parameters conform to ANSI/IEEE Std 754-1985. Please refer to the Standard for more information. PNI also recommends the user refer to the compiler’s instructions to understand how the compiler implements floating-point format. 32 Bit Floating Point (Float32) Shown below is the 32 bit float format in big Endian. In little Endian format, the 4 bytes are in reverse order (LSB first).
Signed 8 Bit Integer (SInt8) UInt8-based parameters are unsigned 8-bit numbers. Bit 7 represents the sign of the value (0=positive, 1=negative) 7 0 byte Unsigned 32 Bit Integer (UInt32) UInt32-based parameters are unsigned 32 bit numbers. 31 24 23 16 15 8 7 msb 0 lsb Big Endian 7 0 15 8 23 16 31 lsb 24 msb Little Endian Unsigned 16 Bit Integer (UInt16) UInt16-based parameters are unsigned 16 bit numbers.
FourCharCode FourCharCode is a four-byte parameter. 7 0 7 ASCII Char 1 5.3 07 ASCII Char 2 07 ASCII Char 3 0 ASCII Char 4 Commands & Communication Frames Table 5-1: V2Xe Command Set Frame ID Command Description Set Up 0x01 kGetModInfo Queries the device’s type and firmware revision.
kGetModInfoResp (frame ID 0x02) The response to kGetModInfo is given below. The payload contains the device type identifier followed by the firmware revision number. Payload Type Revision FourCharCode FourCharCode kSetConfig (frame ID 0x06) This frame sets internal configurations in the V2Xe. The first byte of the payload is the configuration ID followed by a format-specific value. These configurations can only be set one at time. To save these in non-volatile memory, the kSave command must be issued.
kDeclination (Config. ID 0x01) This sets the declination angle to determine True North heading. Positive declination is easterly declination and negative is westerly declination. This is not applied unless kTrueNorth is set to TRUE. kTrueNorth (Config. ID 0x02) Flag to set compass heading output to true north heading by adding the declination angle to the magnetic north heading. kCalSampleFreq (Config. ID 0x03) This sets the sampling frequency during calibration. kSampleFreq (Config.
the “n” number elements. Damping is only applied to the heading data. This is not a running average but instead an average of the most recent “n” number with the oldest being dropped in each successive heading calculation. kGetConfig (frame ID 0x07) This frame queries the TCM for the current internal configuration value. The payload contains the configuration ID requested. Payload Config ID UInt8 kGetConfigResp (frame ID 0x08) The response to kGetConfig is given below.
By performing a calibration, the V2Xe identifies local sources of distortion and negates their effects from the overall reading to provide an accurate heading. For more on magnetic distortion and calibration, see PNI’s white paper “Local Magnetic Distortion Effects on 3Axis Compassing” at PNI’s website (http://www.pnicorp.com/technology/papers). Follow the steps below to perform a calibration: Mount the V2Xe in the host system in its operating position and as level as possible.
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.
Table 5-4: Component Identifiers Component Component ID Format Units kXRaw 0x01 SInt32 counts kYRaw 0x02 Sint32 counts kXCal 0x03 Float32 scaled to 1.0 kYCal 0x04 Float32 scaled to 1.0 kHeading 0x05 Float32 degrees kMagnitude 0x06 Float32 scaled to 1.0 kTemperature 0x07 Float32 °C kDistortion 0x08 Boolean True or False kCalStatus 0x09 Boolean True or False Component types are listed below. All are read-only values.
After a request for data is sent, a time delay is required for processing and sampling. The time delay required is relative to the period select value being used and is also influenced by the strength of field being measured. With a period select value of 8 (/4096), a delay of approximately 50 msec is required. The delay proportionately decreases with decreasing period select value. The kGetData sequence should be: Send kGetData. Delay. Push 1 byte out of V2Xe module.
