EVAL-AD7891-1CB Datasheet, PDF (7/12 Pages) Analog Devices – Evaluation Board for Single Supply, 12-Bit 454 kSPS ADC

EVAL-AD7891-1CB
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 AD7891-1 to perform a number of conversions as
determined by the setup menu (see above). The data
from these conversions is then analyzed by the
AD7891-1 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.
F5: Save. This saves a set of samples to a file for use either
at a later date or with other software. The samples can
be saved either as "volts", "ints" or "binary". The
format of all these files is ASCII text. Note that the
AD7891 software can only load files saved in the "ints"
format. Files saved in the "volts" and "ints" formats can
be used with packages such as Mathcad. Files saved in
the "binary" format are for viewing purposes only.
F6: Load. This allows the user to load data from a file
with a .DAT extension. Only data that was saved as
ints can be loaded and analyzed. A configuration file
must be loaded via the "F2 Setup" menu before the
data file can be analyzed. If there is no EVAL-
CONTROL BOARD connected to the PC, then the
"no prog" button in the "F2 Setup" menu must be on.
Once a configuration file has been loaded, the data
loaded from the .DAT file is analyzed according to the
settings in the "F2 Setup" menu.
F7: Reset. Choosing this option resets the EVAL-
CONTROL BOARD.
F10: Quit. This quits the AD7891-1 evaluation software
and returns control to the operating system.
Information Windows
There are three information windows at the top of the main
screen. The leftmost window is the configuration window and
gives details about part being evaluated. It shows the name of
the program which has been downloaded to the EVAL-CON-
TROL BOARD, the sampling frequency, the number of bits,
the analog input range of the part and the output code format of
the part. The rightmost large window is the Status window.
This window provides feedback to the user as to what opera-
tions are currently being performed by the software and also
displays error messages. Directly underneath the status window
is a small window that shows the maximum and minimum
values of the most recently captured samples.
Test Mode
At the top right of the main screen are the Test Mode buttons.
These buttons determine what sort of testing is done on the
samples captured by the software. Both an ac analysis and dc
analysis can be performed. The function of these buttons are:
fft plot
Choosing this button causes the Digital Spectrum
Analyzer to appear at the bottom of the screen.
histogram: Choosing this button causes the Histogram
Analyzer to be displayed at the bottom of the
screen.
There is one other button near the top of the screen, beside the
"F10 Quit" button. This is:
blackman-harris: When performing a fourier transform of the
sampled data, this button determines whether or not
the data is windowed by a blackman-harris window
before the transform. When this button is on, the data
is windowed. When this button is off, the data isn't
windowed. See the Digital Spectrum Analyzer section
for more details.
REV. A
–7–