PNI SENtral User Manual

Page 22

PNI Sensor Corporation

Doc #1018049 R03

SENtral Technical Data Sheet

Page 21

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 1/10

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

(30

), 0x0A (10

), and 0x14 (20

o The actual accelerometer and gyro ODRs are limited to the ODRs supported by

the specific sensors. 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.



Establish the quaternion or Euler angle output data rate, where the output data rate

equals GyroRate divided by QRateDivisor. The default for QRateDivisor is 0x00,
which is interpreted as ‘1’ and results in the output data rate equaling GyroRate.



Establish how SENtral’s orientation and sensor data is to be output. The
AlgorithmControl register allows the user to select either quaternion or Euler angles

(heading, pitch, and roll) for orientation outputs, and either scaled or raw sensor data

outputs. The default is 0x00, corresponding to quaternion and scaled sensor data.



Establish which events will trigger an interrupt to the host by configuring the

EnableEvent register. PNI specifically recommends enabling bit [1], the Error

interrupt bit, in addition to whichever other interrupts the user wants.

Example steps to do this are below:



Write 0x640A0F to the MagRate register. Since SENtral automatically increments to

the next register, this also populates the AccelRate and GyroRate registers. This sets

MagRate to 100 Hz, AccelRate to 100 Hz, and GyroRate to 150 Hz.



Write 0x01 to the QRateDivisor Register. This sets the quaternion output data rate to

equal the GyroRate. For writing 0x01 this step is optional, since the default also sets

the quaternion output data rate equal to GyroRate.



Write 0x06 to the AlgorithmControl register. This enables heading, pitch, and roll

orientation outputs and raw sensor data outputs. This step is optional, as the default