EVAL-AD7766/AD7767
Preliminary Technical Data
Connect the CED and the evaluation board together via the 96
way connector.
Apply power to the CED via the supplied ac transformer.
The USB cable can then be connected between the PC and the
CED.
If it is the first time that the CED has been connected to the PC,
the PC will automatically find the new device and will identify
it. Follow the onscreen instructions that appear automatically.
This installs the drivers for the CED on the PC.
RUNNING THE SOFTWARE
To launch the software, from the
Analog Devices
menu select
the
AD7766
submenu, then click on
AD7766.
Figure 6 displays
the main software window. The main function of this window is
to allow you 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 three main
sections.
The top portion of the screen contains the control buttons. The
control buttons allow you to take samples, program the board,
and to exit the program.
Control Buttons
Clicking the
Program Board
button programs the CED to
operate with the AD7766/AD7767 evaluations board. This
enables all the required signals that are to be generated to run
the AD7766/67 device. Prior to taking samples the AD7766/67
device the user must provide a SYNC/PD pulse to the
AD7766/67 device. Press the
Sync / Power Down
button so that
the AD7766/67 device is set-up to sample. This process must be
followed each time the CED is powered up. Following the
SYNC/PD samples can be acquired from the AD7766/67 device.
The
Exit
button quits the program.
The
Sample
button instructs the CED to take the required
number of samples at the required throughput rate from the
evaluation board. The AD7766/AD7767 evaluation board runs
using a 1.024MHz MCLK. You can choose the sampling
frequency up to this rate by setting the MCLK frequency on the
AD7766/67 front panel. Please note though that the MCLK
frequency supplied by the CED board is not controlled by the
MCLK setting on the software front panel, it is set constant to
1.024Mhz. However if an an external MCLK signal is applied
the MCLK control on the front panel may be used so that all the
frequency calculations from the results of the samples are scaled
correctly.
The number of samples to be taken is set using the
Num
Samples
controls. The SCLK frequency is set at 20MHz and is
used to transfer all data from the AD7766/AD7767 device to
the CED board this SCLK frequency is constant. Note that the
SCLK will only run when the
Sample
or
Continuous
buttons
have been clicked. The samples taken are uploaded and
displayed. An FFT and/or histogram can be calculated and
displayed.
The
Continuous
button instructs the software to repeat the
sampling process indefinitely until you click
Stop.
(The
Continuous
button switches to
Stop
when clicked). While the
software is continuously sampling data, the other control
buttons are disabled except the
Stop
button. Please note that
there is a certain delay (associated with data transfer on the USB
link) which means that the data shown in Continuous mode is
not sequential data. The mode is designed so that the user can
see multiple sets of samples without having to constantly click
the Sample button.
Digital Storage Oscilloscope
The middle section of the screen is a digital storage oscilloscope
(DSO) that allows you to display a waveform, a histogram or an
FFT. When samples are uploaded from the CED they are
displayed here.
At the bottom left of the graph are the zoom options. These
allow you to zoom in and out to get a closer look at a sample, if
required. The right-hand side of the middle section contains
information about the samples taken, for example, minimum/
maximum, the spread, the standard deviation, and the mean.
Fast Fourier Transform or Histogram
The lower section of the window is also a digital storage
oscilloscope (DSO) that allows you to display a waveform, a
histogram, or an FFT. The FFT (the default option) is typically
used for examining the ADC’s performance in the frequency
domain while the histogram gives an indication of the ADC’s
performance in response to dc inputs. The option displayed can
be changed by clicking on the
Waveform
,
Histogram
, and
FFT
buttons. The right-hand side of the lower section contains
information about the samples taken, for example, ac
specifications.
Rev. PrA | Page 8 of 20
