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

ID 683122
Date 3/28/2022
Public

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1.6.4. Assigning I/O Registers

The Precision Synthesis software performs timing-driven I/O register mapping by default. You can force a register to the device IO element (IOE) using the Complex I/O constraint. This option does not apply if you turn off I/O pad insertion.
Note: You also can make the assignment by right-clicking on the pin in the Schematic Viewer.

For the Stratix series, Cyclone series, and the MAX II device families, the Precision Synthesis software can move an internal register to an I/O register without any restrictions on design hierarchy.

For more mature devices, the Precision Synthesis software can move an internal register to an I/O register only when the register exists in the top-level of the hierarchy. If the register is buried in the hierarchy, you must flatten the hierarchy so that the buried registers are moved to the top-level of the design.