DMU380ZA Series
User’s Manual
________________________________________________________________________
Doc# 7430-3810 Rev.02
Page 43
discussion of the process is discussed in the section Mag Alignment Procedure found in
Appendix A: Installation and Operation of NAV-VIEW.
To initiate a magnetic alignment over the SPI bus, perform a write to register 0x50 by
appending the write-bit/address combination with 0x01, e.g. 0xD001. Table 29 provides
a description of the mag-alignment register.
Table 29 Magnetic-Alignment Register
(Base Address: 0x50), Read/Write
Bits
Description (Default: 0x0000)
[ 15:8 ]
Mag-Align Initiation byte
[ 7:0 ]
Mag-Align Status byte
0x00: Disabled (default)
0x0B: Alignment process complete
0x0C: Alignment process in-progress
Once the mag-align procedure has begun, the Mag-Align Status byte will be set to 0x0C.
The master must monitor the least-significant byte of register 0x50 to assess test status.
Once the byte changes to 0x0B the alignment procedure is complete. At this point, the
hard-iron and soft-iron estimates are written to registers 0x48 through 0x4F and saved to
the EEPROM. The Kalman filter algorithm is reset to stabilization mode. It remains in
this state for five seconds to allow the user to bring the system to rest while the
initialization process completes.
Conversion factors from values in the hard and soft-iron registers (0x48 through 0x4E) to
decimal equivalents are provided in Table 30.
Table 30 DMU380 Magnetic Alignment Parameters
Name
Register
Address
Format
Scaling
Range
Units
X-Axis Hard-Iron Bias 0x48
Signed-Integer
20/2^16
[ -10,10 ]
Gauss
Y-Axis Hard-Iron Bias 0x4A
Signed-Integer
20/2^16
[ -10,10 ]
Gauss
Soft Iron Scale Ratio
0x4C
Unsigned-Integer 2/2^16
[ 0,2 ]
N.D.
Soft-Iron Angle
0x4E
Signed-Integer
2*pi/(2^15
–
1)
[ -pi,pi ]
Radians
Suggested Operation
5.8
The following operational procedure and timing specifications should be adhered to
while communicating with the DMU380 via SPI to ensure proper system operation.
These points are further highlighted later in this section.
Startup Timing
The following timing applies at system startup (Figure 15):
During system setup, the DMU380 should be held in reset (nRST line held low)
until the SPI master is configured and the system is ready to begin
communications with the DMU380
After releasing the reset line, the DMU380 requires 100 msec (t
System Delay
) before
the system is ready for use
