《STM32启动代码分析正》.doc

STM32启动代码分析[转] ?? 启动代码文件名是STM32F10X.S，它的作用先总结下，然后再分析。启动代码作用一般是：1）堆和栈的初始化；2）向量表定义；3）地址重映射及中断向量表的转移；4）设置系统时钟频率；5）中断寄存器的初始化；6）进入C应用程序。 ?? （1）按启动代码的次序，先看堆和栈的初始化： Stack_Size????? EQU???? 0????? ；定义Stack_Size为0??????????????? AREA??? STACK, NOINIT, READWRITE, ALIGN=3?? ；定义栈，可初始为0，8字节对齐Stack_Mem?????? SPACE?? Stack_Size?????? ；分配0x200个连续字节，并初始化为0__initial_sp?? ；汇编代码地址标号 ? Heap_Size?????? EQU???? 0??????????????? AREA??? HEAP, NOINIT, READWRITE, ALIGN=3__heap_baseHeap_Mem??????? SPACE?? Heap_Size__heap_limit ??????????????? PRESERVE8?；指定当前文件堆栈8字节对齐??????????????? THUMB???? ；告诉汇编器下面是32为的Thumb指令，如果需要汇编器将插入位以保证对齐 ??（2）中断向量表定义 AREA??? RESET, DATA, READONLY ;定义复位向量段，只读??????????????? EXPORT? __Vectors?? ；定义一个可以在其他文件中使用的全局标号。此处表示中断地址 __Vectors?????? DCD???? __initial_sp????????????? ;?给__initial_sp分配4字节32位的地址0x0??????????????? DCD???? Reset_Handler???????????? ; 给标号Reset Handler分配地址为0??????????????? DCD???? NMI_Handler?????????????? ; 给标号NMI Handler分配地址0??????????????? DCD???? HardFault_Handler???????? ; Hard Fault Handler??????????????? DCD???? MemManage_Handler???????? ; MPU Fault Handler??????????????? DCD???? BusFault_Handler????????? ; Bus Fault Handler??????????????? DCD???? UsageFault_Handler??????? ; Usage Fault Handler??????????????? DCD???? 0???????????????????????? ;?这种形式就是保留地址，不给任何标号分配??????????????? DCD???? 0???????????????????????? ; Reserved??????????????? DCD???? 0???????????????????????? ; Reserved??????????????? DCD???? 0???????????????????????? ; Reserved??????????????? DCD???? SVC_Handler?????????????? ; SVCall Handler??????????????? DCD???? DebugMon_Handler????????? ; Debug Monitor Handler??????????????? DCD???? 0???????????????????????? ; Reserved??????????????? DCD???? PendSV_Handler??????????? ; PendSV Handler??????????????? DCD???? SysTick_Handler?????????? ; SysTick Handler ??????????????? ; External Interrupts??????????????? DCD???? WWDG_IRQHandler?????????? ; Window Watchdog?????