KXTI9-1001 Datasheet, PDF (41/54 Pages) List of Unclassifed Manufacturers – 2g/4g/8g Tri-axis Digital Accelerometer Specifications

± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
PART NUMBER:
KXTI9-1001
Rev. 2
Jul-2011
the screen orientation change. When the device orientation angle approaches 0° (device is flat on a
desk or table), a_x = a_y = 0g, a_z = +1g, and there is no way to determine which way the screen should be
oriented, the internal algorithm determines that the device is in either the face-up or face-down
orientation, depending on the sign of the z-axis. The KXTI9 will only change the screen orientation
when the orientation angle is above the factory-defaulted/user-defined threshold set in the
TILT_ANGLE register. Equation 2 can be used to determine what value to write to the TILT_ANGLE
register to set the device orientation angle.
TILT_ANGLE (counts) = sin θ * (32 (counts/g))
Equation 2. Tilt Angle Threshold
Tilt Timer
The 8-bit register, TILT_TIMER can be used to qualify changes in orientation. The KXTI9 does this by
incrementing a counter with a size that is specified by the value in TILT_TIMER for each set of
acceleration samples to verify that a change to a new orientation state is maintained. A user defined
output data rate (ODR) determines the time period for each sample. Equation 3 shows how to
calculate the TILT_TIMER register value for a desired delay time.
TILT_TIMER (counts) = Delay Time (sec) x ODR (Hz)
Equation 3. Tilt Position Delay Time
Motion Interrupt Feature Description
The Motion interrupt feature of the KXTI9 reports qualified changes in the high-pass filtered acceleration based
on the Wake Up (WUF) threshold. If the high-pass filtered acceleration on any axis is greater than the user-
defined wake up threshold (WUF_THRESH), the device has transitioned from an inactive state to an active
state. When configured in the unlatched mode, the KXTI9 will report when the motion event finished and the
device has returned to an inactive state. Equation 4 shows how to calculate the WUF_THRESH register value
for a desired wake up threshold. Note that this calculation varies based on the configured g-range of the part.
WUF_THRESH (counts) = Wake Up Threshold (g) x Sensitivity (counts/g)
Equation 4. Wake Up Threshold
36 Thornwood Dr. – Ithaca, NY 14850
tel: [phone] – fax:[phone]
www.kionix.com - [e-mail]
© 2011 Kionix – All Rights Reserved
438-2322-1107191455
Page 41 of 54