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Q:
ISE 跑bit时遇到342错误。
ERROR:Bitgen:342 - This design contains pins which have locations (LOC) that arenot user-assigned or I/O Standards (IOSTANDARD) that are not user-assigned.This may cause I/O contention or incompatibility with the board power orconnectivity affecting performance, signal integrity or in extreme casescause damage to the device or the components to which it is connected. To prevent this error, it is highly suggested to specify all pin locations and I/O standards to avoid potential contention or conflicts and allow proper bitstream creation. To demote this error to a warning and allow bitstream creation with unspecified I/O location or standards, you may apply the following bitgen switch: -g UnconstrainedPins:Allow![]()
A: 这种问题仅存在于用ISE开发7系列芯片时才会出现。根据中文翻译，可能是顶层文件中的某信号没有用到，或约束文件没有对管脚约束导致。
还有一种比较隐藏的情况。顶层文件中的输出端口信号d1，在代码中不受任何其它信号控制，直接为0或1，这样综合后这个管脚其实是没有用到的，因此约束时报错。或顶层文件中某个输入管脚din2，在程序中要本没有用到这个信号驱动内部电路，也会因约束管脚出错。
