MMA865xFC Sensor Toolbox User’s Guide, Rev. 0
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Freescale Semiconductor, Inc.
Table 5. Graphical Datalogger – Configuration screen
Screen frame
Field or option
Description
Datalogger
Operation
Data Source
Select the device's data reading resolution. A higher number of bits produces
more-precise values, but it requires more time and power.
• Selecting the 8-bit option causes the program to read only the 8 bits stored in the X, Y,
and Z MSB registers.
• Selecting 12 bits for the MMA8652FC reads the 8 MSB bits and the 4 bits stored in the
X, Y, and Z LSB registers.
• Selecting 10 bits for the MMA8653FC reads the 8 MSB bits and the 2 bits stored in the
X, Y, and Z LSB registers.
Method
This drop-down list enables you to select how the data is read from the device.
• Select ODR to display data read directly from the device’s output registers.
• Select FIFO to display data collected in the device FIFO.
To use the functions in the FIFO Configuration frame, the FIFO option must be
selected.
Sensor Rate
This drop-down list enables you to select the rate that the accelerometer collects data at.
Note:
While sensor rate options above 200 Hz are included in the list (because the
device is capable of operating at these rates), 200 Hz is the highest sensor rate at
which the Datalogger can function— therefore these sensor rates will not be
selectable in this application.
Operation
Mode
Enable Low Noise
Enables the device’s Low Noise Mode for more accurate readings.
Note:
In Enable Low Noise mode, any g-force greater than ±4g will not be read.
Over-Sampling
Options for Data
Normal Mode
Normal operation.
Hi Res Mode
The device gives more accurate readings, but draws more
current.
Low Power Mode
The device draws less current than Normal mode does, but at
the expense of accuracy.
Low Noise Low Power
The device draws more current than Normal mode does, but
less current than Low Power mode does, and reduces noise.
Auto Calibrate
Directs the device to calculate the offsets for each axis (accounting for any error in
measurements). For maximum resolution, the calibration is done with a dynamic range
of 8g and a sample rate of 1.563 Hz.
Note:
Before enabling Auto Calibrate mode, place the device on a flat and stationary
surface.
Dynamic
Range
• 2g
• 4g
• 8g
Sets the range over which the accelerometer acquires data.
FIFO
Configuration
To use the functions in this frame, the Method drop-down field must be set to FIFO.
Fill Buffer
option button
Fills the FIFO with data and then dumps that data to the Acceleration graph each time
that the FIFO is full.
Circular Buffer
option button
Fills the FIFO with data and then begins feeding it out from the beginning of the FIFO.
This will cause a 32-point lag between when the data is acquired and when it is displayed
on the graph.
Watermark
slider
Set the sample number to be stored in the FIFO before the Watermark Flag is asserted.