Data Sheet

BNO055
Data sheet
Page 45
BST-BNO055-DS000-14 | Revision 1.4 | June 2016 Bosch Sensortec
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Note: Specifications within this document are subject to change without notice.
3.8.2.5 Gyroscope Any Motion Interrupt
Any-motion (slope) detection uses the slope between successive angular rate signals to
detect changes in motion. An interrupt is generated when the slope (absolute value of
angular rate difference) exceeds a preset threshold. It is cleared as soon as the slope falls
below the threshold. The principle is made clear in Figure 4.
Figure 4: Principle of any-motion detection
The threshold is defined through register GYR_AM_THRES. In terms of scaling 1 LSB of
GYR_AM_THRES corresponds to 1 °/s in 2000°/s-range (0.5°/s in 1000°/s-range, 0.25°/s in
500°/s -range …). Therefore the maximum value is 125°/s in 2000°/s-range (62.5°/s
1000°/s-range, 31.25 in 500°/s -range …).
The time difference between the successive angular rate signals depends on the selected
update rate(fs) which is coupled to the bandwidth and equates to 1/(4*fs) (t=1/(4*fs)). For
bandwidth settings with an update rate higher than 400Hz (bandwidth =0,1,2) fs is set to
400Hz.
In order to suppress false triggers, the interrupt is only generated (cleared) if a certain
number N of consecutive slope data points is larger (smaller) than the slope threshold given
by GYR_AM_THRES. This number is set by the Slope Samples bits in the GYR_AM_SET
register. It is N = [Slope Samples + 1]*4. N is set in samples. Thus the time is scaling with the
update rate (fs).
slope_th
INT
slope
angular rate
rate(t
0
)
rate(t
0
−1/(4*fs))
slope(t
0
)=gyro(t
0
)−gyro(t
0
−1/(2*bw))
time
time
time
slope_dur
slope_dur