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AR# 51407

Vivado 2013.4 - How to avoid DRC errors due to unconstrained pins in bitstream generation

Description

The following DRC errors occur when running bitstream generation for a design with unconstrained pins:

Running DRC as a precondition to command write_bitstream

ERROR: [Drc 23-20] Rule violation (NSTD-1) Unspecified I/O Standard - 3 out of 45 logical ports use I/O standard (IOSTANDARD) value 'DEFAULT', instead of a user assigned specific value. This may cause I/O contention or incompatibility with the board power or connectivity affecting performance, signal integrity or in extreme cases cause damage to the device or the components to which it is connected. To correct this violation, specify all I/O standards. This design will fail to generate a bitstream unless all logical ports have a user specified I/O standard value defined. To allow bitstream creation with unspecified I/O standard values (not recommended), use set_property BITSTREAM.General.UnconstrainedPins {Allow} on the current design. Problem ports: init_calib_complete, sys_rst, tg_compare_error.

ERROR: [Drc 23-20] Rule violation (UCIO-1) Unconstrained Logical Port - 3 out of 45 logical ports have no user assigned specific location constraint (LOC). This may cause I/O contention or incompatibility with the board power or connectivity affecting performance, signal integrity or in extreme cases cause damage to the device or the components to which it is connected. To correct this violation, specify all pin locations. This design will fail to generate a bitstream unless all logical ports have a user specified site LOC constraint defined. To allow bitstream creation with unspecified pin locations (not recommended), use set_property BITSTREAM.General.UnconstrainedPins {Allow} on the current design. Problem ports: init_calib_complete, sys_rst, tg_compare_error.

How can I avoid these errors?

Solution

The Vivado tool does not allow bitstream generation to be run for designs with unconstrained I/O unless the default behavior is overridden with the following property entered at the TCL console:

set_property BITSTREAM.General.UnconstrainedPins {Allow} [current_design]
AR# 51407
Date Created 08/21/2012
Last Updated 02/04/2014
Status Active
Type General Article
Tools
  • Vivado Design Suite