原答案来自原答案

报错如下

[Drc 23-20] Rule violation (NSTD-1) Unspecified I/O Standard - 4 out of 142 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: USBIND_0_port_indctl[1:0], USBIND_0_vbus_pwrfault, USBIND_0_vbus_pwrselect.

新建记事本，添加以下三句：

set_property SEVERITY {Warning} [get_drc_checks NSTD-1]

set_property SEVERITY {Warning} [get_drc_checks RTSTAT-1]

set_property SEVERITY {Warning} [get_drc_checks UCIO-1]

重命名为  name.tcl文件（确定后缀格式有效）

我用的是vivado2017.4 ，在generate bitstream 界面如下，右键进入setting

将新建的.tcl文件添加进来

再一次Generate bitstream  ，大功告成！

具体原因，还请路过的大佬解释一下。