EVAL-AD7899CB Datasheet, PDF (6/12 Pages) –

EVAL-AD7899CB
Figure 2. AD7899 Main Screen
SOFTWARE DESCRIPTION
The software which controls the Evaluation Board Control-
ler and hence the evaluation board has three main screens.
The screen shown in Figure 1 shows the screen which appears
when the software is run. The main function of this screen is
to allow the user to read a predetermined number of samples
from the evaluation board and display them in both the time
and frequency domain. The screen can be divided into 3
sections. The upper third of the screen contains the control
buttons, the menu bar and various status windows. The
control buttons allow the user to enter the setup menu, take
samples and get information about the software. The menu
bar allows the user to select which printer port is to be used
to control the Evaluation Board Controller, load and save
data etc. The status windows indicate the setup of the
evaluation board/device, number of samples taken and any
information/error messages that are generated.
The middle third of the screen is a Digital Storage
Oscilloscope (DSO). When samples are uploaded from the
Evaluation Board Controller they are displayed here. The
samples can be displayed either as integer values or as
voltages (determined by the input range of the device in
question). Once samples have been displayed clicking at any
point in the graph will display the sample number and value
of the point directly beneath the cursor. Along the axis of the
graph are the "zoom handles". These allow the user to zoom
in and out to get a closer look at a particular sample if
required. When another set of samples is taken the graph will
attempt to display all values collected unless the Hold Zoom
check box is ticked. In this case the graph will keep the same
axis settings as for the previous set of data samples. Addi-
tional check boxes are provided to give the user control over
the vertical and horizontal grids and data points.
The lower third of the screen will show either a Fast
Fourier Transform (FFT) of the data or a Histogram which
shows the number of occurrances of each particular code read
back. The FFT (the default option) is typically used when the
user is concerned with examining an ADC's performance in
the frequency domain while the Histogram will give an
indication of the ADC's performance to DC signals. The
option displayed can be toggled by clicking on the FFT
Mode/Histogram Mode button in the top right of the screen.
Figure 3 shows how the main screen looks when the Histo-
gram Option is selected.
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