EVAL-AD7891-2CB Datasheet, PDF (7/12 Pages) Analog Devices – Evaluation Board for Single Supply, 12-Bit 500 kSPS ADC

EVAL-AD7891-2CB
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-AD7891-2CB. 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-
2.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 AD7891-2. 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 5 V
for the ± 2.5 V or 0 to 5V inputs and to 2.5 V for the 0 to 2.5 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.
Main Screen
The top left part of the main screen contains eight buttons
which are selected using the mouse or by using the function keys
from the keyboard. These buttons and the actions they perform
are:
F1: Info. Activating this button provides information on
the software.
F2: Setup . Pressing this button pops up the Setup Menu.
This menu is described above.
F3: Samp. When this key is pressed, the software causes
the AD7891-2 to perform a number of conversions as
determined by the setup menu (see above). The data
from these conversions is then analyzed by the
AD7891-2 evaluation software. Another set of samples
may be taken by pressing the F3 key again.
F4: Cont. Pressing this button causes the software to
repeatedly perform conversions and analyze them.
Once the conversions and analysis has been done for
one set of samples, the software automatically repeats
the process. It continues to do this until the ESC key
is pressed.
REV. A
Figure 4. Setup Screen
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