Intel® Quartus® Prime Standard Edition User Guide: Third-party Synthesis

ID 683796
Date 9/24/2018
Document Table of Contents Register Packing

Intel devices allow register packing into I/O cells. Intel recommends allowing the Intel® Quartus® Prime software to make the I/O register assignments. However, you can control register packing with the syn_useioff attribute. The syn_useioff attribute is a Boolean data type value that can be applied to ports or entire modules. Setting the value to 1 instructs the compiler to pack the register into an I/O cell. Setting the value to 0 prevents register packing in both the Synplify and Intel® Quartus® Prime software.