在stm32f1xx.h file文件中找到如下代码：
/* Uncomment the line below according to the target STM32L device used in your
application
*/
#if !defined (STM32F100xB) && !defined (STM32F100xE) && !defined (STM32F101x6) && \
!defined (STM32F101xB) && !defined (STM32F101xE) && !defined (STM32F101xG) && !defined (STM32F102x6) && !defined (STM32F102xB) && !defined (STM32F103x6) && \
!defined (STM32F103xB) && !defined (STM32F103xE) && !defined (STM32F103xG) && !defined (STM32F105xC) && !defined (STM32F107xC)
/* #define STM32F100xB */ /*!< STM32F100C4, STM32F100R4, STM32F100C6, STM32F100R6, STM32F100C8, STM32F100R8, STM32F100V8, STM32F100CB, STM32F100RB and STM32F100VB */
/* #define STM32F100xE */ /*!< STM32F100RC, STM32F100VC, STM32F100ZC, STM32F100RD, STM32F100VD, STM32F100ZD, STM32F100RE, STM32F100VE and STM32F100ZE */
/* #define STM32F101x6 */ /*!< STM32F101C4, STM32F101R4, STM32F101T4, STM32F101C6, STM32F101R6 and STM32F101T6 Devices */
/* #define STM32F101xB */ /*!< STM32F101C8, STM32F101R8, STM32F101T8, STM32F101V8, STM32F101CB, STM32F101RB, STM32F101TB and STM32F101VB */
/* #define STM32F101xE */ /*!< STM32F101RC, STM32F101VC, STM32F101ZC, STM32F101RD, STM32F101VD, STM32F101ZD, STM32F101RE, STM32F101VE and STM32F101ZE */
/* #define STM32F101xG */ /*!< STM32F101RF, STM32F101VF, STM32F101ZF, STM32F101RG, STM32F101VG and STM32F101ZG */
/* #define STM32F102x6 */ /*!< STM32F102C4, STM32F102R4, STM32F102C6 and STM32F102R6 */
/* #define STM32F102xB */ /*!< STM32F102C8, STM32F102R8, STM32F102CB and STM32F102RB */
/*#define STM32F103x6 */ /*!< STM32F103C4, STM32F103R4, STM32F103T4, STM32F103C6, STM32F103R6 and STM32F103T6 */
/* #define STM32F103xB */ /*!< STM32F103C8, STM32F103R8, STM32F103T8, STM32F103V8, STM32F103CB, STM32F103RB, STM32F103TB and STM32F103VB */
/* #define STM32F103xE */ /*!< STM32F103RC, STM32F103VC, STM32F103ZC, STM32F103RD, STM32F103VD, STM32F103ZD, STM32F103RE, STM32F103VE and STM32F103ZE */
/* #define STM32F103xG */ /*!< STM32F103RF, STM32F103VF, STM32F103ZF, STM32F103RG, STM32F103VG and STM32F103ZG */
/* #define STM32F105xC */ /*!< STM32F105R8, STM32F105V8, STM32F105RB, STM32F105VB, STM32F105RC and STM32F105VC */
/* #define STM32F107xC */ /*!< STM32F107RB, STM32F107VB, STM32F107RC and STM32F107VC */
#endif
然后找到你用的MCU去掉其前后的注释即可！