MPU-6000 INVENSENSE, MPU-6000 Datasheet - Page 28

• Manufacturer Part Number: MPU-6000
• Description: IC, GYRO/ACCEL, 9-AXIS FUSION, PROG
• Manufacturer: INVENSENSE

Specifications of MPU-6000

• Acceleration Range: ± 2g, ± 4g, ± 8g
• No. Of Axes: 9
• Sensor Case Style: QFN
• No. Of Pins: 24
• Supply Voltage Range: 2.5V To 3.6V
• Operating Temperature Range: -40°C To +85°C
• Interface: I2C, SPI
• Interface Type: I2C, SPI
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The diagram below shows the signal path for the gyroscope and accelerometer sensors. Note that each
digital low pass filter (DLPF) is configured identically, as is each sample rate divider and digital high pass
filter (DHPF).
Free fall is detected by checking if the accelerometer measurement from all three axes has an absolute
value below a user-programmable threshold (acceleration threshold). For each sample where this condition
is true (a qualifying sample), a counter is incremented. For each sample where this condition is false (a non-
qualifying sample), the counter is decremented. Once the counter reaches a user-programmable threshold
(the counter threshold), the Free Fall interrupt is triggered, and a flag is set. The flag is cleared once the
counter has decremented to zero. The counter does not increment above the counter threshold or decrement
below zero.
The user is given several configuration parameters to fine tune Free Fall detection. Both, the acceleration
threshold and counter threshold, are user configurable. The FF_THR register allows the user to set a
threshold in steps of 1mg. The FF_DUR register allows the user to set duration in steps of 1 ms.
The decrement rate for non-qualifying samples may also be configured. The MOT_DETECT_CTRL register
allows the user to specify whether a non-qualifying sample makes the counter reset to zero, or decrement in
steps of 1, 2, or 4.
The plots in the figure above show an example acceleration input signal (simplified to only show one axis),
qualifying sample counter, and Free Fall flag.
The MPU-60X0 provides Motion detection capability that works in a similar manner to Free Fall detection.
Accelerometer measurements are passed through a configurable digital high pass filter (DHPF) in order to
eliminate bias due to gravity. A qualifying motion sample is one where the high passed sample from any axis
has an absolute value exceeding a user-programmable threshold. A counter increments for each qualifying
sample, and decrements for each non-qualifying sample. Once the counter reaches a user-programmable
CONFIDENTIAL & PROPRIETARY
8.1
8.2
8.3
Free Fall, Motion, and Zero Motion Signal Paths
Free Fall Interrupt
Motion Interrupt
MPU-6000/MPU-6050 Product Specification
28 of 53
Document Number: PS-MPU-6000A-00
Revision: 1.0
Release Date: 11/24/2010