STM32报错identifier "xxx" is undefined，找不到某些符号（符号未定义）的问题

 

对于新手来说，编译STM32工程的时候时常会遇到找不到定义的问题，如下：

..\HARDWARE\EXTI\exti.c(4): error:  #20: identifier "EXTI_InitTypeDef" is undefined
        EXTI_InitTypeDef EXTI_InitStructure;//定?宄?始化?峁???
..\HARDWARE\EXTI\exti.c(17): error:  #20: identifier "EXTI_Line2" is undefined
  EXTI_InitStructure.EXTI_Line=EXTI_Line2; //?卸??叩谋旰? 取值范围为EXTI_Line0~EXTI_Line15
..\HARDWARE\EXTI\exti.c(18): error:  #20: identifier "EXTI_Mode_Interrupt" is undefined
  EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;//?卸?模式，??选值为?卸? EXTI_Mode_Interrupt ???录? EXTI_Mode_Event。
..\HARDWARE\EXTI\exti.c(19): error:  #20: identifier "EXTI_Trigger_Falling" is undefined
  EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;//触发方式，???????陆??卮シ? EXTI_Trigger_Falling，?????卮シ? EXTI_Trigger_Rising，???????獾?平（?????睾??陆??兀┐シ?EXTI_Trigger_Rising_Falling
..\HARDWARE\EXTI\exti.c(21): warning:  #223-D: function "EXTI_Init" declared implicitly
  EXTI_Init(&EXTI_InitStructure);//?萁峁?????息???谐?始化
..\HARDWARE\EXTI\exti.c(33): warning:  #223-D: function "EXTI_GetITStatus" declared implicitly
  if(EXTI_GetITStatus(EXTI_Line2)!=RESET)//?卸?某?????系??卸??欠穹??? 
..\HARDWARE\EXTI\exti.c(33): error:  #20: identifier "EXTI_Line2" is undefined
  if(EXTI_GetITStatus(EXTI_Line2)!=RESET)//?卸?某?????系??卸??欠穹??? 
..\HARDWARE\EXTI\exti.c(37): warning:  #223-D: function "EXTI_ClearITPendingBit" declared implicitly
   EXTI_ClearITPendingBit(EXTI_Line2);   //?宄? LINE ?系??卸媳?志位
..\HARDWARE\EXTI\exti.c: 3 warnings, 5 errors


stm32f10x_it.c(86): warning:  #223-D: function "TIM_GetITStatus" declared implicitly
      if(TIM_GetITStatus(TIM2,TIM_IT_Update)!=RESET)
stm32f10x_it.c(86): error:  #20: identifier "TIM_IT_Update" is undefined
      if(TIM_GetITStatus(
IM2,TIM_IT_Update)!=RESET)
stm32f10x_it.c(89): warning:  #223-D: function "TIM_ClearITPendingBit" declared implicitly
      TIM_ClearITPendingBit(TIM2,TIM_IT_Update);

 其实解决方法很简单，就是在工程中引入官方库函数，通常在一个完整的库函数工程中，会存在这个文件夹：STM32F10x_FWLib，这个文件夹中的文件就是库函数所在，完整的文件夹中通常会存在以下文件：

├─inc
│      misc.h
│      stm32f10x_adc.h
│      stm32f10x_bkp.h
│      stm32f10x_can.h
│      stm32f10x_cec.h
│      stm32f10x_crc.h
│      stm32f10x_dac.h
│      stm32f10x_dbgmcu.h
│      stm32f10x_dma.h
│      stm32f10x_exti.h
│      stm32f10x_flash.h
│      stm32f10x_fsmc.h
│      stm32f10x_gpio.h
│      stm32f10x_i2c.h
│      stm32f10x_iwdg.h
│      stm32f10x_pwr.h
│      stm32f10x_rcc.h
│      stm32f10x_rtc.h
│      stm32f10x_sdio.h
│      stm32f10x_spi.h
│      stm32f10x_tim.h
│      stm32f10x_usart.h
│      stm32f10x_wwdg.h
│
└─src
        misc.c
        stm32f10x_adc.c
        stm32f10x_bkp.c
        stm32f10x_can.c
        stm32f10x_cec.c
        stm32f10x_crc.c
        stm32f10x_dac.c
        stm32f10x_dbgmcu.c
        stm32f10x_dma.c
        stm32f10x_exti.c
        stm32f10x_flash.c
        stm32f10x_fsmc.c
        stm32f10x_gpio.c
        stm32f10x_i2c.c
        stm32f10x_iwdg.c
        stm32f10x_pwr.c
        stm32f10x_rcc.c
        stm32f10x_rtc.c
        stm32f10x_sdio.c
        stm32f10x_spi.c
        stm32f10x_tim.c
        stm32f10x_usart.c
        stm32f10x_wwdg.c

则时候，如果用到某些功能的时候，在sys.h中引入对应的头文件，然后将对应的*.c文件加入工程编译即可解决问题。