..\Output\串口通信.axf: Error: L6218E: Undefined symbol DMA_GetITStatus (referred from stm32f10x_it.o).
..\Output\串口通信.axf: Error: L6218E: Undefined symbol DMA_Cmd (referred from dma.o).
..\Output\串口通信.axf: Error: L6218E: Undefined symbol DMA_ITConfig (referred from dma.o).
..\Output\串口通信.axf: Error: L6218E: Undefined symbol DMA_Init (referred from dma.o).