EVAL-AD7707EB Datasheet, PDF (10/16 Pages) Analog Devices – Evaluation Board for the AD7707 3V/5V, +/-10V Input Range, 1mW, 3Channel, 16-Bit, Sigma Delta ADC

EVAL-AD7707EB
The Calibration Registers Screen
Fig. 8. shows the Calibration Registers screen. When this screen is displayed the values of the Gain and Offset Registers are
read from the AD7707 and displayed. The user has the ability to change the values of either register if required. the default
value for the fullscale cal register is 5761AB hex and the default value for the zero scale cal register is 1F4000 hex.
The Read Data Screen
Fig. 9. shows the Read Data screen. This is where the user can read a number of samples from the AD7707. The user has
the option of either reading data for analysis or display.
When the Read For Analysis button is selected the software will read the required number of samples from the AD7707 and
store them in an array so that they can be graphed or analysed later. It is possible to read upto 5000 samples at any one time
although only 3000 can be displayed on a graph.
Fig. 9. The Read Data Screen
When the Read for Display button is selected the software will read one sample from the AD7707 and display its value in the
Current Code text box. The software will continue to read and display the samples until a key has been pressed. It is possible
to add a delay to the read cycle by checking the Use Delay Value checkbox. If the box is checked the software will wait the
required number of milliseconds between reading samples. It should be noted however that the accuracy of the time delay can
be affected by other programs running under Windows, therefore this method is not suitable where equidistant sampling is
required.
The Noise Analysis Screen
Once data has been read from the AD7707 it is possible to perform some analysis on it. Fig. 10. shows the Noise Analysis
Screen. This screen displays the maximum and minimum codes read from the AD7707 (in decimal and hexadecimal), as well
as the average code, the average voltage and the RMS and Peak-Peak noise values. From this screen it is possible to display
the data on a graph or as a histogram of codes. Figures 11 and 12 show the Graph and Histogram screens.
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