EVAL-AD7898CB Datasheet, PDF (6/13 Pages) Analog Devices – Evaluation Board for 5V, 12-Bit, Serial 220kSPS ADC in 8-Pin Package

EVAL-AD7898CB
Figure 2. AD7898 Main Screen - FFT Mode
SOFTWARE DESCRIPTION FOR MODE 1 OPERATION
Included in the EVAL-AD7898CB evaluation board package is a CD ROM which contains software for controlling and
evaluating the performance of the AD7898 when it is operated with the EVALUATION-BOARD CONTROLLER. When
the CD is inserted into the PC an installation program will automatically begin. This program will install the evaluation
software onto the users machine and will also install the technical Note for the AD7898 evaluation board as well as the datasheet
for the AD7898. All literature on the CD is in Adobe's Portable Documation format (PDF) and will require Acrobat Reader^TM
to be viewed or printed. The user interface on the PC is a dedicated program written especially for the AD7898.
The software which controls the Evaluation Board Controller and hence the AD7898 evaluation board has three main screens.
The screen shown in Figure 2 shows the screen which appears when the software is run. The main function of the 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 most section of the screen contains the control buttons,
the menu bar and the status windows.The control buttons allow the user to enter the set-up menu, take samples, and get
information about the software. The control buttons also allow the user change from mode 0, ( the default mode on power
up ) to Mode 1 , the operating mode of the AD7898 evaluation board. There are also power down/up options in the control
buttons. These buttons allow the user to place the part into power down, and power the part up again. When the AD7898
evaluation board is first powered up and the AD7898.cfg file is loaded, the Mode 1 option button should be pressed, this places
the AD7898 into Mode 1 (the mode of operatiuon of the evaluation board).
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 window indicates the set up of the AD7898 evaluation board, the number of samples taken and any
information messages that are generated.
The middle section of the AD7898 Main 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 as either interger values or as voltages
( +/- 2.5 V for the AD7898 -3 and +/- 10 V for AD7898-10 ). Once the samples are displayed clicking any point on the graph
will display the sample number and the 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 are taken the graph will attempt to display all values collected unless the Hold Zoom check box is ticked. If
the Hold zoom box is ticked the graph will keep the same axis settings as for the previous set of data samples. There are
additional check boxes in this section to give the user control over the vertical and horizontal grids and data points.
The lowest section of the screen will show either a Fast Fourier Transform (FFT) of the data, or a histogram, which shows
the number of occurances of each particular code read back. The FFT ( default option ) is typically used when the user is
concerned with examining the AD7898's performance in the frequency domain, while the Histogram will give an indication
of the AD7898's performance to dc signals. The option displayed can be changed by clicking on the FFT Mode/Histogram
Mode button in the top right of the screen. Figure 3 shows how the Main Screen would look if the Histogram Mode was
selected.
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