Design Entry Techniques
CPLD Schematic Design Guide
2-17
some behavioral compilers, such as XABEL. PLUSASM is still recog-
nized and processed by this version of the fitter for the sake of
existing behavioral modules based on that interface. However, future
versions of the software will not support PLUSASM and it should not
be used when creating any new behavioral modules.
If the behavioral compiler tool supports the development of
completely behavioral designs, make sure you select the appropriate
mode of operation or compilation flow for producing logic modules,
not stand-alone designs. The netlist produced by the compiler must
not contain device I/O pin information. If any of the terminal nodes
(inputs or outputs) of your behavioral module are to be connected to
CPLD device pins, you must use IBUF and OBUF symbols in your
schematic.
Note:
If you are using a synthesis tool to prepare a behavioral
module, make sure you target the appropriate CPLD technology
library.
Your compiled behavioral module file is normally stored in your
project directory. You can also copy it to a user library directory if you
want to use it for more than one project.
Behavioral Module Symbols in Schematics
Using a behavioral module in a schematic design involves creating a
symbol to represent your logic, placing the symbol into your sche-
matic and applying necessary attributes to identify the logic-defining
file.
1.
Use the symbol editing facility of your schematic entry tool to
create a symbol representing your behavioral logic. Generally, the
name of your symbol will be the name of the behavioral module,
although this is not mandatory.
Place a pin on your symbol for each terminal node (input or
output port) in your behavioral design that needs to be connected
to other logic or I/O ports in your schematic. "Buried" nodes that
connect only between logic functions within the behavioral
module do not require pins on your symbol.
Some tools have commands or utilities that automatically
generate symbols based on the terminal nodes defined in your
behavioral module.
Summary :
Design Entry Techniques CPLD Schematic Design Guide 2-17 some behavioral compilers, such as XABEL. Behavioral Module Symbols in Schematics Using a behavioral module in a schematic design involves creating a symbol to represent your logic, placing the symbol into your sche- matic and applying necessary attributes to identify the logic-defining file.
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