Cirrus Logic CDB5451A - Manual (Page 17)

CDB5451A
DS458DB3 17
3.2.4.2. Time Domain / FFT / Histogram
Selector
This selector button is located just to the right of the
Collect Button. The label on this button will change
as the user selects which analysis is to be per-
formed (“Time Domain” or “FFT” or “Histogram”).
When the software is first started, the default mode
on this selector button is Time Domain. This user
should click on this button to select which type of
data processing to perform on the collected data
and display in the plot area. Refer to the section on
Analyzing Data for more information.
3.2.4.3. “Crystal” Value Indicator Box
The value in this box reflects the frequency of the
CS5451A’s clock input (at the XIN pin). Since the
XIN frequency affects the sampling rate (the output
word rate) of the CS5451A, this information must
be specified to the software so that it can accurate-
ly depict the frequency-content of the sampled
data (in Hz) when performing an FFT analysis.
The user can enter the crystal frequency that is
used on the CDB5451A board into this box. The
default value of this box is set for the on-board
4.096MHz oscillator.
3.2.4.4. OWRS Pin Setting:
This switch should be adjusted whenever the user
toggles the S1-1 DIP switch (on the evaluation
board). The default setting of this switch is HI, cor-
responding to the default setting on S1-1 (default
setting is “OPEN”). S1-1 drives the CS5451A’s
OWRS pin to logic “1”. A logic “1” on OWRS sets
the sampling frequency of all six CS5451A input
channels to XIN/1024. To toggle the state of the
on-screen switch, simply click on the switch with
the mouse.
3.2.4.5. Config Button
This button will bring up the configuration window
(shown in Fig 7) in which the user can modify the
data collection specifications. See the discussion
of the Config Window in this document.
3.2.4.6. Save Button
The red-colored SAVE button will save the data in
the current plot to a file. The exact path and filena-
me can be specified by the user in the text window
located just to the left of the SAVE button. The
data collected for all six channels will be saved to
a text file.
3.2.4.7. Load Button
The green colored LOAD button will load any data
file that was previously generated by clicking on
the red SAVE button. The exact path and filename
must be specified by the user in the text window lo-
cated just to the left of the LOAD button.
3.2.4.8. Channel Selector Buttons
Clicking on six buttons labeled as “V1” “V2” “V3”
and “I1” “I2” “I3” will display a certain channel of da-
ta. “V1” refers to the data taken from the
Vin1+/Vin1- input pins of the CS5451A. This is
similar for “V2” and “V3”. In a similar manner, click-
ing on the “I1” “I2” “I3” buttons will display the volt-
age measured across the first, second, and third
pairs of current channel input pins (designated as
IinA+/IinA- for A = 1, 2, 3).
3.2.5 Config Window
See Figure 7. Clicking on the Config button will
bring up a small pop-up window called the Config
Window. The Config Window allows the user to
set up the data collection and analysis parameters,
which are described next.
3.2.5.1. Number of Samples
This box allows the user to select the number of
samples to collect. The user can choose any
whole-number power of 2 between 16 and 32768.
3.2.5.2. Average
When performing FFT processing, this box will de-
termine the number of FFTs to average. FFTs will
then be collected and averaged when the user
clicks on the Collect Button.
3.2.5.3. FFT Window
This box allows the user to select the type of win-
dowing algorithm for FFT processing. Windowing
algorithms include the Blackman, Black-Harris,
Hanning, 5-term Hodie, and 7-term Hodie. The 5-
term Hodie and 7-term Hodie are windowing algo-
rithms developed at Cirrus Logic.