EVAL-AD7891-1CB Datasheet, PDF (6/12 Pages) Analog Devices – Evaluation Board for Single Supply, 12-Bit 454 kSPS ADC

EVAL-AD7891-1CB
Figure 3. Main Screen
SOFTWARE DESCRIPTION
Included in the EVAL-AD7891-1CB evaluation board package
is a PC-compatible disk which contains software for controlling
and evaluating the performance of the AD7891-1 when it is
operated with the EVAL-CONTROL BOARD. The EVAL-
AD7891-1CB Demonstration/Evaluation Software runs under
DOS 4.0 or later and requires a minimum of a 386-based
machine with 400kB of base RAM and 500kB of free hard disk
space. The user interface on the PC is a dedicated program
written especially for the AD7891-1.
The disk which accompanies the EVAL-AD7891-1CB contains
several files. The user should create a new directory on the main
PC drive and label this "AD7891-1". Then, all files on the
EVAL-AD7891-1CB disk should be copied into this directory.
The Mouse Driver on the PC should be enabled before running
the software. If this has not been loaded, the program will not
run.
To run the software, simply make the AD7891-1 directory the
current directory and type "go". When the evaluation program
starts, the user sees the screen shown on Figure 3 (without any
FFT or scope waveforms). This is the main screen and it is
divided into three parts. The top part provides the main control
interface for the AD7891-1 evaluation software. The middle
part of the main screen functions as a Digital Storage
Oscilliscope and the bottom part of the main screen operates as
either a Digital Spectrum Analyzer or a Histogram analyzer.
Each part of the screen has several buttons that can be pressed
by using the mouse or the keyboard. To press a button using
the mouse, simply use it to move the on-screen pointer to the
button to be activated and click. To use the keyboard, simply
press the appropriate key as highlighted on the button. Lower
case letters must be used. When a button is pressed, it is
highlighted on the screen. The next button can be highlighted
by using the Tab key or the previous button by holding down
the shift key and the Tab key together. The highlighted button
can also be pressed by pressing the space bar. Pressing the ESC
key halts any operation currently in progress. In this document, if
a button can be activated from the keyboard then the key used is
shown in bold in the button name. For example, "no prog" has the
"p" highlighted in bold, indicating that the button can be activated by
pressing the p key.
Some buttons have a red indicator. A red indicator on the
button means that the function associated with that button is
on. Absence of the red indicator light means that the function
associated with the button is off. The on/off status of these
buttons is changed simply by selecting the button.
Figure 4. SetupScreen
Setting up the EVAL-CONTROL BOARD
When the software is run, the "F2 Setup" button in the top left
of the screen should be selected to pop up the setup menu.
This menu sets up the EVAL-CONTROL BOARD for use with
the EVAL-AD7891-1CB. The Setup Menu is shown in Figure
4.
Firstly, a configuration file must be chosen. The configuration
file contains the default configuration information for the
EVAL-CONTROL BOARD, the Digital Spectrum Analyzer
and the Digital Storage Oscilliscope. It also tells the AD7891-
1.EXE software which .HIP file to download to the ADSP-
2111. The .HIP file contains the DSP code which is executed
by the ADSP-2111. Normally, the "no prog" button is off, so
when the configuration file is loaded, the .HIP file is automati-
cally downloaded to the ADSP-2111. However, if the "no prog"
button is on, then the .HIP file is not downloaded to the ADSP-
2111.
There are two configuration files for the AD7891-1. If an
external CONVST pulse is being used, then the configuration
file "AD7891EX" must be chosen. The mouse or the keyboard
is used to highlight the "AD7891EX" option and the "load
device file" button is pressed. The other configuration file
option is chosen when using the CONVST signal generated by
the EVAL-CONTROL BOARD. The mouse or the keyboard is
used to highlight the "AD7891IN" option and, again, the "load
device file" button is pressed. See Appendix A for further
information about the .CFG files.
After the configuration file is loaded, the sample rate and
number of samples can be changed. If the internal CONVST
option is in use, then the available CONVST frequencies are
limited to frequencies of the form 16 MHz/N, where N is an
integer in the range 1 to 65536. If a frequency other than one
of these frequencies is chosen, then the EVAL-CONTROL
BOARD generates the next lowest available frequency.
The input voltage range and the input voltage offset are shown
in the Analog Input "Range" and "Offset". These figures can be
altered if requried. The input voltage range should be set to 10
V for a ± 5 V input or to 20 V for a ± 10 V input. The offset
voltage should be set to the input voltage which causes the ADC
to return a code of zero. These figures are used for calculating
the Max, Min and PPk (peak to peak) voltage numbers in the
oscilliscope window and also for histogram analyzer
calcualtions.
–6–
REV. A