XtremeDSP Spartan-3A DSP Development Board - Technical reference guide - v1.1
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To select I/O settings
1.
Modify the input clock
frequency from 20 MHz to 25 MHz so that it matches the clock input frequency of the
XtremeDSP Spartan-3A DSP Development Board.
2.
Click the
Detailed I/O
.
The following window appears.
Figure 7 Detailed I/O configuration of the 5V9885
3.
In the
Input Clock Configurations
group, select the
Crystal Input Enable
check box.
4.
In the
Output OUTx Control
group, clear the
/Out5 Invert
check box.
On the XtremeDSP Spartan-3A DSP Development Board, clock output 5 is usually used as a differential
clock.
5.
Click
Close
.
6.
Under
Output Clock Frequencies
, type the clock output frequencies in the appropriate text boxes.
7.
To calculate the register values necessary to produce the clock frequencies, click
Auto Calculate
.
The
Auto Calculation Result
window appears.
8.
Click
OK
to close the window.
Under each text box where you typed a value, blue text indicates the frequencies to be produced. When you
see a double dash (- -) instead of a numerical value, the software was unable to create this combination of
clock frequencies. Modify the settings until all the clock outputs are numerical values.
During startup, the chip loads its settings depending on the GIN input pins. By default, the software loads
from the configuration-0 settings. The configuration used by the XtremeDSP Spartan-3A DSP Development
Board requires some register modifications to function properly.
