Altera ASI MegaCore Function - Manual (Page 22)

January 2014 Altera Corporation Asynchronous Serial Interface (ASI) MegaCore Function User Guide
A. Constraints
Introduction
For the ASI MegaCore function to work reliably, you must implement the following
Quartus II constraints:
■ Specify clock characteristics
■ Set timing exceptions such as false path, minimum delay and maximum delay
■ Minimize the timing skew among the paths from I/O pins to the four sampling
registers
■ Set the oversampling clock that is used by the oversampling interface to 135 MHz
as an independent clock domain
Constraint Design With TimeQuest Timing Analyzer
To ensure your design meets timing and other requirements, you must constrain the
design. This section provides the necessary steps to properly constrain your ASI
design using TimeQuest timing analyzer.
1. Set up the Quartus II TimeQuest timing analyzer.
a. To specify the Quartus II TimeQuest timing analyzer as the default timing
analyzer, on the Assignments menu, click Settings.
b. In the Settings dialog box, under the Category list, select Timing Analysis
Settings .
c. Turn on Use TimeQuest Timing Analyzer during compilation option, and
click OK.
2. Perform initial compilation to create an initial design database before you specify
timing constraints for your design. On the Processing menu, click Start
Compilation
.
3. Run the Quartus II TimeQuest timing analyzer. On the Tools menu, click
TimeQuest Timing Analyzer .
4. Create timing netlist based on the fully annotated database from the post-fit
results, after you perform a full compilation. Double-click Create Timing Netlist
in the Tasks pane.
5. Write SDC constraint file. The Quartus II software does not automatically update
.sdc files. You must explicitly write new or update constraints in the TimeQuest
timing analyzer. On the Constraints menu, click Write SDC File to write your
constraints to an .sdc file.
6. Specify timing constraints and exceptions. To enter your timing requirements, you
can use constraint entry dialog boxes or edit the previously created .sdc file.