原因1：配置相应的中断向量表
原因2：配置相应的寄存器
总结原因：
因为所有的 stm32f10x 系列的芯片都会用到 stm32f10x.h 这个头文件，
但是问题的所在是：每种芯片的配置不同（中断向量个数、寄存器个数等等）
因此宏条件编译 #if !defined 判断这个宏（这个宏就是 STM32F10X_LD/MD/HD)，配置不同芯片的参数。
官方对不同芯片的宏定义参照以下内容：
/* #define STM32F10X_LD */ /*!< STM32F10X_LD: STM32 Low density devices */
/* #define STM32F10X_LD_VL */ /*!< STM32F10X_LD_VL: STM32 Low density Value Line devices */
/* #define STM32F10X_MD */ /*!< STM32F10X_MD: STM32 Medium density devices */
/* #define STM32F10X_MD_VL */ /*!< STM32F10X_MD_VL: STM32 Medium density Value Line devices */
/* #define STM32F10X_HD */ /*!< STM32F10X_HD: STM32 High density devices */
/* #define STM32F10X_HD_VL */ /*!< STM32F10X_HD_VL: STM32 High density value line devices */
/* #define STM32F10X_XL */ /*!< STM32F10X_XL: STM32 XL-density devices */
/* #define STM32F10X_CL */ /*!< STM32F10X_CL: STM32 Connectivity line devices */
- Low-density devices are STM32F101xx, STM32F102xx and STM32F103xx microcontrollers
where the Flash memory density ranges between 16 and 32 Kbytes.
- Low-density value line devices are STM32F100xx microcontrollers where the Flash
memory density ranges between 16 and 32 Kbytes.
- Medium-density devices are STM32F101xx, STM32F102xx and STM32F103xx microcontrollers
where the Flash memory density ranges between 64 and 128 Kbytes.
- Medium-density value line devices are STM32F100xx microcontrollers where the
Flash memory density ranges between 64 and 128 Kbytes.
- High-density devices are STM32F101xx and STM32F103xx microcontrollers where
the Flash memory density ranges between 256 and 512 Kbytes.
- High-density value line devices are STM32F100xx microcontrollers where the
Flash memory density ranges between 256 and 512 Kbytes.
- XL-density devices are STM32F101xx and STM32F103xx microcontrollers where
the Flash memory density ranges between 512 and 1024 Kbytes.
- Connectivity line devices are STM32F105xx and STM32F107xx microcontrollers.
由上面的引用可知，STM32F103C8T6 为64KB FLASH，应该为STM32F10X_MD 。
野火教程使用的 STM32F103VET6 为 512KB FLASH， 应该为STM32F10X_HD。
标签：MD,LD,density,STM32F10X,devices,Keil,HD,define From： https://www.cnblogs.com/FBsharl/p/17505968.html