EM7180SFP

Copyright

2014, EM Microelectronic-Marin SA

7180SFP-DS Version 1.1, 10-Dec-14

6

www.emmicroelectronic.com

420005-A01, 2.0

2.3. Normal Operation

During Normal Operation the sensors and SENtral algorithm will run and it will be possible to obtain real-time orientation and

motion-tracking data from SENtral. The registers used in Normal Operation are given in Table 6.

Register Name

Address

Register Value

HostControl

0x34

[0] 1 = Run Request

0 = Enable Initialized State

MagRate

0x55

Requested magnetometer output data rate

AccelRate

0x56

Requested accelerometer output data rate divided by 10

GyroRate

0x57

Requested gyroscope output data rate divided by 10

ActualMagRate

0x45

Actual magnetometer output data rate

ActualAccelRate

0x46

Actual accelerometer output data rate divided by 10

ActualGyroRate

0x47

Actual gyroscope output data rate divided by 10

QRateDivisor

0x32

Along with GyroRate, establishes output data rate for

quaternion data.

EnableEvents

0x33

‘1’ indicates an interrupt to the host will be generated for the

event.

[0] CPUReset. Non-maskable

[1] Error

[2] QuaternionResult

[3] MagResult

[4] AccelResult

[5] GyroResult

[6] Reserved

[7] Reserved

EventStatus

0x35

‘1’ indicates a new event has been generated.

[0] CPUReset

[1] Error

[2] QuaternionResult

[3] MagResult

[4] AccelResult

[5] GyroResult

Table 6 Normal Operation Registers

Prior to entering the Normal Operation state it is necessary to perform the following

:

-

Set the sensor output data rates (ODRs): MagRate, AccelRate, and GyroRate. If a sensor rate is set to 0x00, SENtral

will shutdown the sensor and disable SENtral background calibration. There are two major points regarding setting

these registers:

o

The AccelRate and GyroRate register values should be 1/10th the desired rate, while the MagRate value

should match the desired ODR. For example, if the desired ODR is 30 Hz for the magnetometer, 100 Hz for

the accelerometer, and 200 Hz for the gyroscope, then the respective register values should be 0x1E (30d),

0x0A (10d), and 0x14 (20d).

o

The actual accelerometer and gyro ODRs are limited to the ODRs supported by the specific sensors (in this

case BMX055). If the AccelRate or GyroRate register values do not correspond to a supported ODR, then the

next highest ODR will be used. For instance, if the GyroRate register is set to 0x14, which corresponds to

200 Hz, but the gyro supports 95 Hz, 190 Hz, and 380 Hz, then the actual gyro ODR will be 380 Hz since this

is the closest supported rate above that requested by the register. During Normal Operation, the actual sensor

rates can be read from ActualMagRate, ActualAccelRate and ActualGyroRate registers.

-

Establish the quaternion output data rate, where the quaternion output data rate equals GyroRate divided by

QRateDivisor. The default for QRateDivisor is 0x00, which is interpreted as ‘1’ and results in the quaternion output

data rate equalling GyroRate.

-

Establish which events will trigger an interrupt to the host by configuring the EnableEvent register. It is specifically

recommended to enable bit [1], the Error interrupt bit, in addition to whichever other interrupts the user wants.