Digital Signal Processing Reference
In-Depth Information
pages 6 and 7 and jump to page 8 of the MegaWizard manager. Click
Finish
again to complete the MegaWizard manager and create the files for the PLL
component.
Double click on a blank area of the top-level schematic file. Select the
Project
up3_pll
module and add it to your top-level schematic as shown in the
completed schematic in Figure 17.17.
IMPORTANT NOTE:
Different or future versions of the Altera software may
generate slightly different hardware time delays for the SDRAM clock. If you
experience SDRAM errors after running memory tests on your final design or
the program downloads to SDRAM do not verify, and after double checking
that everything else is correct in your design, the PLL phase shift may need to
be adjusted a small amount. Most designs seem to fall within about 30 degrees
of -54 degrees. This corresponds to a time delay adjustment of only 1 or 2 ns.
17.17 Complete the Top-Level Schematic
To complete the top-level schematic, add the input, output, and bi-directional
pins (and pin names) shown in Figure 17.17. Also, complete the connections
between the two top-level components as shown in the figure. Finally, if you
added the LCD component for the DE2 board, add a VCC symbol and connect
it to the
LCD_ON
and
LCD_BLON
output pins to tie them High. If you have
trouble reading the signal names in the figure, the file is available on the DVD.
17.18 Design Compilation
Verify that the pin assignments discussed in Section 17.2 were made correctly
by going to
Assignments
Pins
. A long list of pin numbers and names
corresponding to the pin names you entered into the top-level schematic should
appear. If it does not, then repeat the steps in Section 17.2 to import the pin
assignments.
Verify that the global assignments discussed in Section 17.2 were made
correctly by going to
Assignments
Device…
Device & Pin Options
Unused Pins
.
The
Reserve all unused pins
option should be set to
As input tri-stated
. If it
is not, then select this option. Click
OK
until all dialog boxes are closed.
Select
Processing
Start Compilation
to begin compiling your project.
