Example26_DSP2833x_SPI_loopback.out" not built

undefined     first referenced
  symbol           in file     
---------     ----------------
_InitScibGpio ./APP/c/uart.obj

error #10234-D: unresolved symbols remain
error #10010: errors encountered during linking; "Example26_DSP2833x_SPI_loopback.out" not built
求指教，编译出现这种错误是怎么回事、

缺少文件   或调用了未定义的变量