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Freescale Semiconductor Document Number: AN4083
Application Note Rev 0, 08/2012
© 2012 Freescale Semiconductor, Inc. All rights reserved.
Contents
Data Manipulation and Basic Settings for
Xtrinsic MMA865xFC Accelerometers
by:
Fengyi Li
, Applications Engineer
1 Introduction
This document shows you how to configure the
MMA865xFC devices to extract and manipulate the
acceleration data. These devices have been designed to
be compatible with a shared memory map. An example
MMA865xFC Driver Code is available. It is briefly
referred to in this application note, to demonstrate the
device configuration in C.
The MMA8652FC device has all of the embedded
features of this device family, including 8 different
sample rates, 32 different cutoff frequencies for the
high-pass filter, 3 dynamic ranges and 4 oversampling
modes. It also has a 32-sample FIFO for collecting and
storing data, which is the most efficient way to access the
data for minimizing the I
2
C transactions. The FIFO can
collect the regular low-pass filtered data, as well as the
data from the high-pass filter. The manipulation of the
data into different formats is also important for algorithm
development and for display.
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 MMA8652, 3FC 3-axis Accelerometer. . . . . . . . . . . . . . . 2
3 Changing Modes of the MMA8652,3FC . . . . . . . . . . . . . 3
4 Changing Dynamic Range. . . . . . . . . . . . . . . . . . . . . . . . 4
5 Setting the Data Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6 Setting the Oversampling Mode . . . . . . . . . . . . . . . . . . . 8
7 Setting the High-Pass Filter Cutoff Frequency . . . . . . . 11
8 12-bit or 10-bit Data Streaming and Data Conversions. 13
9 8-bit XYZ Data Streaming and Conversions . . . . . . . . . 25
10 Polling Data vs. Interrupts . . . . . . . . . . . . . . . . . . . . . . . 28
11 Using the 32-Sample FIFO . . . . . . . . . . . . . . . . . . . . . . 32
12 MMA865x Driver Quick Start. . . . . . . . . . . . . . . . . . . . . 34
