STM32 启动文件选择

- startup_stm32f10x_ld_vl.s: for STM32 Low density Value line devices 

- startup_stm32f10x_ld.s: for STM32 Low density devices 

- startup_stm32f10x_md_vl.s: for STM32 Medium density Value line devices 

- startup_stm32f10x_md.s: for STM32 Medium density devices 

- startup_stm32f10x_hd.s: for STM32 High density devices 

- startup_stm32f10x_xl.s: for STM32 XL density devices 

- startup_stm32f10x_cl.s: for STM32 Connectivity line devices 

cl：互联型产品，stm32f105/107系列

vl：超值型产品，stm32f100系列

xl：超高密度产品，stm32f101/103系列

ld：低密度产品，FLASH小于64K 

md：中等密度产品，FLASH=64 or 128 

hd：高密度产品，FLASH大于128