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1、问题描述

Vivado Error问题警告如下所示：

[DRC NSTD-1] Unspecified I/O Standard: 1 out of 9 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 this command: set_property SEVERITY {Warning} [get_drc_checks NSTD-1].  NOTE: When using the Vivado Runs infrastructure (e.g. launch_runs Tcl command), add this command to a .tcl file and add that file as a pre-hook for write_bitstream step for the implementation run. Problem ports: SYS_CLK.

 在IO设置界面如下所示：

 对于IO工作电压没有明确定义，因此需要以下操作；

2、解决：

新建 .tcl文件，写入如下内容：

set_property SEVERITY {Warning} [get_drc_checks NSTD-1]set_property SEVERITY {Warning} [get_drc_checks UCIO-1]set_property SEVERITY {Warning} [get_drc_checks RTSTAT-1]

在Vivado setting中加入：

 重新编译后错误警告消失！