Xilinx Constraints Guide

Chapter 4: Xilinx Constraints
MAXPT (Maximum Product Terms)
The MAXPT (Maximum Product Terms) constraint:
• Is an advanced constraint.
Architecture Support
Applicable Elements
• Applies to CPLD devices only.
• Specifies the maximum number of product terms the fitter is permitted to use when
collapsing logic into the node to which MAXPT is applied.
• Overrides the Collapsing P-term Limit setting in ISE® Design Suite for the attached
node.
Applies to CPLD devices only. Does not apply to FPGA devices.
Applies to signals.
Propagation Rules
Applies to the signal to which it is attached.
Syntax Examples
The following examples show how to use this constraint with particular tools or
methods. If a tool or method is not listed, you cannot use this constraint with it.
VHDL Syntax
Declare the VHDL constraint as follows:
attribute maxpt: integer;
Specify the VHDL constraint as follows:
attribute maxpt of signal_name : signal is “integer”;
integer is any positive integer
For more information about basic VHDL syntax, see VHDL Attributes.
Verilog Syntax
Place the Verilog constraint immediately before the module or instantiation.
Specify the Verilog constraint as follows:
(* MAXPT = “integer” *)
integer is any positive integer
For more information about basic Verilog syntax, see Verilog Attributes.
UCF and NCF Syntax
Net “signal_name” maxpt=integer;
Constraints Guide
184 www.xilinx.com UG625 (v. 13.2) July 6, 2011