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101990016

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39P40-P42P43-P45P46-P48P49-P51P52-P54
Sensors
10 NXP Semiconductors
MMA8452Q
3 Terminology
3.1 Sensitivity
The sensitivity is represented in counts/g. In 2 g mode the sensitivity is 1024 counts/g. In 4 g mode the sensitivity is
512 counts/g and in 8 g mode the sensitivity is 256 counts/g.
3.2 Zero-g offset
Zero-g offset (TyOff) describes the deviation of an actual output signal from the ideal output signal if the sensor is stationary. A
sensor stationary on a horizontal surface will measure 0 g in X-axis and 0 g in Y-axis whereas the Z-axis will measure 1 g. The
output is ideally in the middle of the dynamic range of the sensor (content of OUT registers 0x00, data expressed as 2's
complement number). A deviation from ideal value in this case is called zero-g offset. Offset is to some extent a result of stress
on the MEMS sensor and therefore the offset can slightly change after mounting the sensor onto a printed circuit board or
exposing it to extensive mechanical stress.
3.3 Self-test
Self-test checks the transducer functionality without external mechanical stimulus. When self-test is activated, an electrostatic
actuation force is applied to the sensor, simulating a small acceleration. In this case, the sensor outputs will exhibit a change in
their DC levels which are related to the selected full scale through the device sensitivity. When self-test is activated, the device
output level is given by the algebraic sum of the signals produced by the acceleration acting on the sensor and by the electrostatic
test-force.
Sensors
NXP Semiconductors 11
MMA8452Q
4 System Modes (SYSMOD)
Figure 6. MMA8452Q mode transition diagram
All register contents are preserved when transitioning from active to standby mode. Some registers are reset when transitioning
from standby to active. These are all noted in the device memory map register table. The sleep and wake modes are active
modes. For more information on how to use the sleep and wake modes and how to transition between these modes, please refer
to the functionality section of this document.
Table 7. Mode of operation description
Mode
I
2
C bus state
VDD Function description
OFF
Powered down
<1.8V
VDDIO Can be > VDD
• The device is powered off.
• All analog and digital blocks are shutdown.
•I
2
C bus inhibited.
Standby
I
2
C communication is possible
>1.8V
• Only digital blocks are enabled.
analog subsystem is disabled.
• Internal clocks disabled.
• Registers accessible for read/write.
• Device is configured in standby mode.
Active
(wake/sleep)
I
2
C communication is possible
>1.8V
• All blocks are enabled (digital, analog).
OFF
WakeStandby
OFF
Active
SYSMOD = 00
SYSMOD = 10
SYSMOD = 01
Auto-sleep/wake
Condition
VDD > 1.8 V
VDD < 1.8 V
CTRL_REG1
Active bit = 1
CTRL_REG1
Active bit = 0
CTRL_REG1
Active bit = 0
Sensors
12 NXP Semiconductors
MMA8452Q
5 Functionality
The MMA8452Q is a low-power, digital output 3-axis linear accelerometer with a I
2
C interface and embedded logic used to detect
events and notify an external microprocessor over interrupt lines. The functionality includes the following:
• 8-bit or 12-bit data which includes high-pass filtered data
• Four different oversampling options for compromising between resolution and current consumption based on application
requirements
• Additional low-noise mode that functions independently of the oversampling modes for higher resolution
• Low-power and auto-wake/sleep modes for conservation of current consumption
• Single-/double-pulse with directional information one channel
• Motion detection with directional information or freefall one channel
• Transient detection based on a high-pass filter and settable threshold for detecting the change in acceleration above a
threshold with directional information one channel
• Portrait/landscape detection with trip points fixed at 30° and 60° for smooth transitions between orientations.
All functionality is available in 2 g, 4 g or 8 g dynamic ranges. There are many configuration settings for enabling all the different
functions. Separate application notes have been provided to help configure the device for each embedded functionality.
Table 8. Features of the MMA845xQ devices
Feature list MMA8451Q MMA8452Q MMA8453Q
Digital resolution (bits)
14 12 10
Digital sensitivity (counts/g)
4096 1024 256
Data-ready interrupt
Yes Yes Yes
Single-pulse interrupt
Yes Yes Yes
Double-pulse interrupt
Yes Yes Yes
Directional-pulse interrupt
Yes Yes Yes
Auto-wake
Yes Yes Yes
Auto-sleep
Yes Yes Yes
Freefall interrupt
Yes Yes Yes
32-level FIFO
Yes No No
High-pass filter
Yes Yes Yes
Low-pass filter
Yes Yes Yes
Orientation detection portrait/landscape = 30°, landscape to portrait = 60°,
and fixed 45° threshold
Yes Yes Yes
Programmable orientation detection
Yes No No
Motion interrupt with direction
Yes Yes Yes
Transient detection with high-pass filter
Yes Yes Yes
Low-power mode
Yes Yes Yes
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39P40-P42P43-P45P46-P48P49-P51P52-P54

101990016

Mfr. #:
Buy 101990016
Manufacturer:
Seeed Studio
Description:
Acceleration Sensor Development Tools TESSEL ACCELEROMETER MODULE
Lifecycle:
New from this manufacturer.
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