STM32启动过程详解

一、STM32启动文件详细解析

STM32启动文件详细解析（V3.5.0） 以:startup_stm32f10x_hd.s为例

;******************** (C) COPYRIGHT 2011 STMicroelectronics ********************;* File Name          : startup_stm32f10x_hd.s;* Author             : MCD Application Team;* Version            : V3.5.0;* Date               : 11-March-2011;* Description        : STM32F10x High Density Devices vector table for MDK-ARM ;*                      toolchain. ;*                      This module performs:;*                      - Set the initial SP;*                      - Set the initial PC == Reset_Handler;*                      - Set the vector table entries with the exceptions ISR address;*                      - Configure the clock system and also configure the external ;*                        SRAM mounted on STM3210E-EVAL board to be used as data ;*                        memory (optional, to be enabled by user);*                      - Branches to __main in the C library (which eventually;*                        calls main()).;*                      After Reset the CortexM3 processor is in Thread mode,;*                      priority is Privileged, and the Stack is set to Main.;* <<< Use Configuration Wizard in Context Menu >>>   ;*******************************************************************************; THE PRESENT FIRMWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS; WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE TIME.; AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY DIRECT,; INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING FROM THE; CONTENT OF SUCH FIRMWARE AND/OR THE USE MADE BY CUSTOMERS OF THE CODING; INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS.;*******************************************************************************; Amount of memory (in bytes) allocated for Stack; Tailor this value to your application needs; <h> Stack Configuration ;栈定义;   <o> Stack Size (in Bytes) <0x0-0xFFFFFFFF:8>; </h>Stack_Size      EQU     0x00000400;EQU伪指令，作用是左边的符号名代表右边的表达式</span>                AREA    STACK, NOINIT, READWRITE, ALIGN=3;定义栈段：名称为STACK，未初始化，可读写，ELF 的栈段按2^3=8对齐Stack_Mem       SPACE   Stack_Size;分配一片连续的存储区域并初始化为 0，栈空间：0x400个字节__initial_sp;栈空间顶地址                                                  ; <h> Heap Configuration;堆定义;   <o>  Heap Size (in Bytes) <0x0-0xFFFFFFFF:8>; </h>Heap_Size       EQU     0x00000200                AREA    HEAP, NOINIT, READWRITE, ALIGN=3__heap_base;堆空间起始地址Heap_Mem        SPACE   Heap_Size;堆空间:0x200个字节__heap_limit;堆空间结束地址PRESERVE8 ;PRESERVE8 指令指定当前文件保持堆栈八字节对齐THUMB;告诉汇编器下面是32位的Thumb指令，如果需要汇编器将插入位以保证对齐 ; Vector Table Mapped to Address 0 at Reset;中断向量表定义;实际上是在CODE区（假设STM32从FLASH启动，则此中断向量表起始地址即为0x8000000）                AREA    RESET, DATA, READONLY;定义一块数据段<DATA>，只可读<READONLY，默认READWRITE>，段名字是RESET                EXPORT  __Vectors;EXPORT:在程序中声明一个全局的标号__Vectors，该标号可在其他的文件中引用                EXPORT  __Vectors_End;在程序中声明一个全局的标号__Vectors_End                EXPORT  __Vectors_Size;在程序中声明一个全局的标号__Vectors_Size;DCD(DCDU)用于分配一片连续的字存储单元并用指定的数据初始化。__Vectors       DCD     __initial_sp               ; Top of Stack  ;该处物理地址值存储__initial_sp所表示的地址值,即为 __Vetors 标号所表示的值                DCD     Reset_Handler              ; Reset Handler                DCD     NMI_Handler                ; NMI Handler                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                          ; Reserved                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;以下为外部中断向量表                DCD     WWDG_IRQHandler            ; Window Watchdog                DCD     PVD_IRQHandler             ; PVD through EXTI Line detect                DCD     TAMPER_IRQHandler          ; Tamper                DCD     RTC_IRQHandler             ; RTC                DCD     FLASH_IRQHandler           ; Flash                DCD     RCC_IRQHandler             ; RCC                DCD     EXTI0_IRQHandler           ; EXTI Line 0                DCD     EXTI1_IRQHandler           ; EXTI Line 1                DCD     EXTI2_IRQHandler           ; EXTI Line 2                DCD     EXTI3_IRQHandler           ; EXTI Line 3                DCD     EXTI4_IRQHandler           ; EXTI Line 4                DCD     DMA1_Channel1_IRQHandler   ; DMA1 Channel 1                DCD     DMA1_Channel2_IRQHandler   ; DMA1 Channel 2                DCD     DMA1_Channel3_IRQHandler   ; DMA1 Channel 3                DCD     DMA1_Channel4_IRQHandler   ; DMA1 Channel 4                DCD     DMA1_Channel5_IRQHandler   ; DMA1 Channel 5                DCD     DMA1_Channel6_IRQHandler   ; DMA1 Channel 6                DCD     DMA1_Channel7_IRQHandler   ; DMA1 Channel 7                DCD     ADC1_2_IRQHandler          ; ADC1 & ADC2                DCD     USB_HP_CAN1_TX_IRQHandler  ; USB High Priority or CAN1 TX                DCD     USB_LP_CAN1_RX0_IRQHandler ; USB Low  Priority or CAN1 RX0                DCD     CAN1_RX1_IRQHandler        ; CAN1 RX1                DCD     CAN1_SCE_IRQHandler        ; CAN1 SCE                DCD     EXTI9_5_IRQHandler         ; EXTI Line 9..5                DCD     TIM1_BRK_IRQHandler        ; TIM1 Break                DCD     TIM1_UP_IRQHandler         ; TIM1 Update                DCD     TIM1_TRG_COM_IRQHandler    ; TIM1 Trigger and Commutation                DCD     TIM1_CC_IRQHandler         ; TIM1 Capture Compare                DCD     TIM2_IRQHandler            ; TIM2                DCD     TIM3_IRQHandler            ; TIM3                DCD     TIM4_IRQHandler            ; TIM4                DCD     I2C1_EV_IRQHandler         ; I2C1 Event                DCD     I2C1_ER_IRQHandler         ; I2C1 Error                DCD     I2C2_EV_IRQHandler         ; I2C2 Event                DCD     I2C2_ER_IRQHandler         ; I2C2 Error                DCD     SPI1_IRQHandler            ; SPI1                DCD     SPI2_IRQHandler            ; SPI2                DCD     USART1_IRQHandler          ; USART1                DCD     USART2_IRQHandler          ; USART2                DCD     USART3_IRQHandler          ; USART3                DCD     EXTI15_10_IRQHandler       ; EXTI Line 15..10                DCD     RTCAlarm_IRQHandler        ; RTC Alarm through EXTI Line                DCD     USBWakeUp_IRQHandler       ; USB Wakeup from suspend                DCD     TIM8_BRK_IRQHandler        ; TIM8 Break                DCD     TIM8_UP_IRQHandler         ; TIM8 Update                DCD     TIM8_TRG_COM_IRQHandler    ; TIM8 Trigger and Commutation                DCD     TIM8_CC_IRQHandler         ; TIM8 Capture Compare                DCD     ADC3_IRQHandler            ; ADC3                DCD     FSMC_IRQHandler            ; FSMC                DCD     SDIO_IRQHandler            ; SDIO                DCD     TIM5_IRQHandler            ; TIM5                DCD     SPI3_IRQHandler            ; SPI3                DCD     UART4_IRQHandler           ; UART4                DCD     UART5_IRQHandler           ; UART5                DCD     TIM6_IRQHandler            ; TIM6                DCD     TIM7_IRQHandler            ; TIM7                DCD     DMA2_Channel1_IRQHandler   ; DMA2 Channel1                DCD     DMA2_Channel2_IRQHandler   ; DMA2 Channel2                DCD     DMA2_Channel3_IRQHandler   ; DMA2 Channel3                DCD     DMA2_Channel4_5_IRQHandler ; DMA2 Channel4 & Channel5__Vectors_End;Vectors结束__Vectors_Size  EQU  __Vectors_End - __Vectors ;得到向量表的大小,304个字节也就是0x130个字节                 AREA    |.text|, CODE, READONLY ;定义一个代码段，可读，段名字是.text                ;|.text|  用于表示由 C 编译程序产生的代码段，或用于以某种方式与 C 库关联的代码段; Reset handler;利用PROC、ENDP这一对伪指令标记程序开始、结束，把程序段分为若干个过程，使程序的结构加清晰Reset_Handler   PROC                EXPORT  Reset_Handler             [WEAK];WEAK声明其他的同名标号优先于该标号被引用,就是说如果外面声明了的话，调用外面的对应函数                IMPORT  __main;IMPORT:伪指令用于通知编译器要使用的标号在其他的源文件中定义                IMPORT  SystemInit                LDR     R0, =SystemInit;系统初始化                BLX     R0 ;带链接的跳转，切换指令集,跳到SystemInit                LDR     R0, =__main;__main为运行时库提供的函数；完成堆栈，堆的初始化等工作，会调用下面定义的__user_initial_stackheap                BX      R0;切换指令集,main函数不返回跳到__main,进入C的世界                ENDP                ; Dummy Exception Handlers (infinite loops which can be modified)NMI_Handler     PROC                EXPORT  NMI_Handler                [WEAK];不可屏蔽中断处理函数                B       .                ENDPHardFault_Handler\ ;\意为换行                PROC                EXPORT  HardFault_Handler          [WEAK];硬件错误处理函数                B       .                ENDPMemManage_Handler\                PROC                EXPORT  MemManage_Handler          [WEAK]                B       .                ENDPBusFault_Handler\                PROC                EXPORT  BusFault_Handler           [WEAK]                B       .                ENDPUsageFault_Handler\                PROC                EXPORT  UsageFault_Handler         [WEAK]                B       .                ENDPSVC_Handler     PROC                EXPORT  SVC_Handler                [WEAK]                B       .                ENDPDebugMon_Handler\                PROC                EXPORT  DebugMon_Handler           [WEAK]                B       .                ENDPPendSV_Handler  PROC                EXPORT  PendSV_Handler             [WEAK]                B       .                ENDPSysTick_Handler PROC                EXPORT  SysTick_Handler            [WEAK]                B       .                ENDPDefault_Handler PROC;输出异常向量表标号,方便外部实现异常的具体功能,[WEAK]是弱定义的意思,如果外部定义了,优先执行外部定义,否则下面的函数定义                EXPORT  WWDG_IRQHandler            [WEAK]                EXPORT  PVD_IRQHandler             [WEAK]                EXPORT  TAMPER_IRQHandler          [WEAK]                EXPORT  RTC_IRQHandler             [WEAK]                EXPORT  FLASH_IRQHandler           [WEAK]                EXPORT  RCC_IRQHandler             [WEAK]                EXPORT  EXTI0_IRQHandler           [WEAK]                EXPORT  EXTI1_IRQHandler           [WEAK]                EXPORT  EXTI2_IRQHandler           [WEAK]                EXPORT  EXTI3_IRQHandler           [WEAK]                EXPORT  EXTI4_IRQHandler           [WEAK]                EXPORT  DMA1_Channel1_IRQHandler   [WEAK]                EXPORT  DMA1_Channel2_IRQHandler   [WEAK]                EXPORT  DMA1_Channel3_IRQHandler   [WEAK]                EXPORT  DMA1_Channel4_IRQHandler   [WEAK]                EXPORT  DMA1_Channel5_IRQHandler   [WEAK]                EXPORT  DMA1_Channel6_IRQHandler   [WEAK]                EXPORT  DMA1_Channel7_IRQHandler   [WEAK]                EXPORT  ADC1_2_IRQHandler          [WEAK]                EXPORT  USB_HP_CAN1_TX_IRQHandler  [WEAK]                EXPORT  USB_LP_CAN1_RX0_IRQHandler [WEAK]                EXPORT  CAN1_RX1_IRQHandler        [WEAK]                EXPORT  CAN1_SCE_IRQHandler        [WEAK]                EXPORT  EXTI9_5_IRQHandler         [WEAK]                EXPORT  TIM1_BRK_IRQHandler        [WEAK]                EXPORT  TIM1_UP_IRQHandler         [WEAK]                EXPORT  TIM1_TRG_COM_IRQHandler    [WEAK]                EXPORT  TIM1_CC_IRQHandler         [WEAK]                EXPORT  TIM2_IRQHandler            [WEAK]                EXPORT  TIM3_IRQHandler            [WEAK]                EXPORT  TIM4_IRQHandler            [WEAK]                EXPORT  I2C1_EV_IRQHandler         [WEAK]                EXPORT  I2C1_ER_IRQHandler         [WEAK]                EXPORT  I2C2_EV_IRQHandler         [WEAK]                EXPORT  I2C2_ER_IRQHandler         [WEAK]                EXPORT  SPI1_IRQHandler            [WEAK]                EXPORT  SPI2_IRQHandler            [WEAK]                EXPORT  USART1_IRQHandler          [WEAK]                EXPORT  USART2_IRQHandler          [WEAK]                EXPORT  USART3_IRQHandler          [WEAK]                EXPORT  EXTI15_10_IRQHandler       [WEAK]                EXPORT  RTCAlarm_IRQHandler        [WEAK]                EXPORT  USBWakeUp_IRQHandler       [WEAK]                EXPORT  TIM8_BRK_IRQHandler        [WEAK]                EXPORT  TIM8_UP_IRQHandler         [WEAK]                EXPORT  TIM8_TRG_COM_IRQHandler    [WEAK]                EXPORT  TIM8_CC_IRQHandler         [WEAK]                EXPORT  ADC3_IRQHandler            [WEAK]                EXPORT  FSMC_IRQHandler            [WEAK]                EXPORT  SDIO_IRQHandler            [WEAK]                EXPORT  TIM5_IRQHandler            [WEAK]                EXPORT  SPI3_IRQHandler            [WEAK]                EXPORT  UART4_IRQHandler           [WEAK]                EXPORT  UART5_IRQHandler           [WEAK]                EXPORT  TIM6_IRQHandler            [WEAK]                EXPORT  TIM7_IRQHandler            [WEAK]                EXPORT  DMA2_Channel1_IRQHandler   [WEAK]                EXPORT  DMA2_Channel2_IRQHandler   [WEAK]                EXPORT  DMA2_Channel3_IRQHandler   [WEAK]                EXPORT  DMA2_Channel4_5_IRQHandler [WEAK];如下只是定义一些空函数WWDG_IRQHandlerPVD_IRQHandlerTAMPER_IRQHandlerRTC_IRQHandlerFLASH_IRQHandlerRCC_IRQHandlerEXTI0_IRQHandlerEXTI1_IRQHandlerEXTI2_IRQHandlerEXTI3_IRQHandlerEXTI4_IRQHandlerDMA1_Channel1_IRQHandlerDMA1_Channel2_IRQHandlerDMA1_Channel3_IRQHandlerDMA1_Channel4_IRQHandlerDMA1_Channel5_IRQHandlerDMA1_Channel6_IRQHandlerDMA1_Channel7_IRQHandlerADC1_2_IRQHandlerUSB_HP_CAN1_TX_IRQHandlerUSB_LP_CAN1_RX0_IRQHandlerCAN1_RX1_IRQHandlerCAN1_SCE_IRQHandlerEXTI9_5_IRQHandlerTIM1_BRK_IRQHandlerTIM1_UP_IRQHandlerTIM1_TRG_COM_IRQHandlerTIM1_CC_IRQHandlerTIM2_IRQHandlerTIM3_IRQHandlerTIM4_IRQHandlerI2C1_EV_IRQHandlerI2C1_ER_IRQHandlerI2C2_EV_IRQHandlerI2C2_ER_IRQHandlerSPI1_IRQHandlerSPI2_IRQHandlerUSART1_IRQHandlerUSART2_IRQHandlerUSART3_IRQHandlerEXTI15_10_IRQHandlerRTCAlarm_IRQHandlerUSBWakeUp_IRQHandlerTIM8_BRK_IRQHandlerTIM8_UP_IRQHandlerTIM8_TRG_COM_IRQHandlerTIM8_CC_IRQHandlerADC3_IRQHandlerFSMC_IRQHandlerSDIO_IRQHandlerTIM5_IRQHandlerSPI3_IRQHandlerUART4_IRQHandlerUART5_IRQHandlerTIM6_IRQHandlerTIM7_IRQHandlerDMA2_Channel1_IRQHandlerDMA2_Channel2_IRQHandlerDMA2_Channel3_IRQHandlerDMA2_Channel4_5_IRQHandler                B       .                ENDP                ALIGN;默认是字对齐方式，也说明了代码是4字节对齐的;*******************************************************************************; User Stack and Heap initialization 用户堆栈初始化;*******************************************************************************                 IF      :DEF:__MICROLIB;判断是否使用DEF:__MICROLIB（micro lib），如果勾选了micro lib                                 EXPORT  __initial_sp;将栈顶地址、堆起始地址、堆结束地址赋予全局属性，使外部程序可用                 EXPORT  __heap_base                 EXPORT  __heap_limit                                 ELSE;如果没有勾选micro lib                                 IMPORT  __use_two_region_memory;两区堆栈空间，堆和栈有各自的空间地址                 EXPORT  __user_initial_stackheap                 __user_initial_stackheap;标号__user_initial_stackheap，表示用户堆栈初始化程序入口;此处是初始化两区的堆栈空间，堆是从由低到高的增长，栈是由高向低生长的，两个是互相独立的数据段，并不能交叉使用。                 LDR     R0, =  Heap_Mem;保存堆起始地址                 LDR     R1, =(Stack_Mem + Stack_Size);保存栈结束地址                 LDR     R2, = (Heap_Mem +  Heap_Size);保存堆结束地址                 LDR     R3, = Stack_Mem;保存栈起始地址                 BX      LR                 ALIGN                 ENDIF                 END;END命令指示汇编器,已到达一个源文件的末尾;******************* (C) COPYRIGHT 2011 STMicroelectronics *****END OF FILE*****

二、STM32 中断向量表的位置 、重定向

知道怎么跳到main函数了，那么，中断发生后，又是怎么跑到中断入口地址的呢？

从stm32f10x.s可以看到，已经定义好了一大堆的中断响应函数，这就是中断向量表，标号__Vectors，表示中断向量表入口地址，例如：

AREA    RESET, DATA, READONLY ; 定义只读数据段，实际上是在CODE区（假设STM32从FLASH启动，则此中断向量表起始地址即为0x8000000）

                EXPORT  __VectorsIMPORT  OS_CPU_SysTickHandler       IMPORT  OS_CPU_PendSVHandler__Vectors       DCD     __initial_sp              ; Top of Stack                DCD     Reset_Handler             ; Reset Handler                DCD     NMI_Handler               ; NMI Handler                DCD     HardFault_Handler         ; Hard Fault Handler                DCD     MemManage_Handler         ; MPU Fault Handler                DCD     BusFault_Handler          ; Bus Fault Handler                DCD     UsageFault_Handler        ; Usage Fault Handler

这个向量表的编写是有讲究的，跟硬件一一对应不能乱写的，CPU找入口地址就靠它了，bin文件开头就是他们的地址，参考手册RM0008的10.1.2节可以看到排列。

我们再结合CORTEX-M3的特性，他上电后根据boot引脚来决定PC位置，比如boot设置为flash启动，则启动后PC跳到0x08000000。此时CPU会先取2个地址，第一个是栈顶地址，第二个是复位异常地址，故有了上面的写法，这样就跳到reset_handler。

那么这个reset_handler的实际地址是多少.？下面的一堆例如Nmi_handler地址又是多少呢？发生中断是怎么跑到这个地址的呢？下面挨个讲解。

1、我们可以通过反向来得知这些入口地址，查看工程下的map文件就可以看到了，这个地址跟keil里面设置的target->flash起始地址息息相关，实际上我们不太需要关心，让编译器分配，中断向量表放的就是他们的地址。

2、对比ARM7/ARM9内核，Cortex-M3内核则是固定了中断向量表的位置而起始地址是可变化的。

3、进到C语言后会先配置NVIC，NVIC_SetVectorTable()里面可以配置中断向量表的起始地址和偏移，主要是告诉CPU该向量表是位于Flash还是Ram，偏移是多少。例如设置为位于Flash内，偏移就是烧入的程序地址，可在Keil target中设置。这样CPU就知道入口地址了。

4、发生中断后，CPU找到中断向量表地址，然后根据偏移（对号入座）再找到中断地址，这样就跳过去了。

我们截一个图说明一下，map文件：

对应的bin文件，看是不是放的上面地址：

显然，200039c0就是栈顶地址，而08006F21就是reset_handler地址！

如何定位？以放到0x20000000为例

1、keil设置ram起始为0x20000100，我们在0x20000000~0x20000100放中断向量表，其他给程序用

2、设置NVIC_SetVectorTable(NVIC_VectTab_FLASH,0);

3、跳到C时把中断向量表拷贝到0x20000000