1.__nounwind
declaration is incompatible with "__nounwind __interwork __softfp unsigned int __iar_builtin_STREXB(unsigned char, unsigned char volatile *)
解决方法:右击工程进入options->C/C++Compiler->Preprocessor删除
$PROJ_DIR$\..\Libraries\CMSIS\CM3\CoreSupport
2.打不开”core_cm3.h”
cannot open source file "core_cm3.h"
原因:没有选MCU型号
解决方法:右击工程进入options->General Options->Target选设备,选设备完后进入Library Configuration,勾选CMSIS内的Use CMSIS