启动文件由汇编编写，是系统上电复位后第一个执行的程序。主要做了以下工作：
1. 初始化堆栈指针 SP=_initial_sp
2. 初始化 PC 指针 =Reset_Handler
3. 初始化中断向量表
4. 配置系统时钟
5. 调用 C 库函数 _main 初始化用户堆栈，从而最终调用 main 函数去到 C 的世界
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?Stack—栈
开辟栈的大小为 0X00000400（1KB），名字为 STACK， NOINIT 即不初始化，可读可写， 8（2^3）字节对齐。栈的作用是用于局部变量，函数调用，函数形参等的开销，栈的大小不能超过内部 SRAM 的小。如果编写的程序比较大，定义的局部变量很多，那么就需要修改栈的大小。如果某一天，你写的程序出现了莫名奇怪的错误，并进入了硬 fault 的时候，这时你就要考虑下是不是栈不够大，溢出了。EQU：宏定义的伪指令，相当于等于，类似与 C 中的 define。AREA：告诉汇编器汇编一个新的代码段或者数据段。 STACK 表示段名，这个可以任意命名；NOINIT 表示不初始化； READWRITE 表示可读可写， ALIGN=3，表示按照 2^3 对齐，即 8 字节对齐。SPACE：用于分配一定大小的内存空间，单位为字节。这里指定大小等于 Stack_Size。标号 __initial_sp 紧挨着 SPACE 语句放置，表示栈的结束地址，即栈顶地址，栈是由高向低生长的?
Stack_Size EQU 0x00000400 ; 1KB
AREA STACK, NOINIT, READWRITE, ALIGN=3
Stack_Mem SPACE Stack_Size
__initial_spHeap 堆
开辟堆的大小为 0X00000200（512 字节），名字为 HEAP， NOINIT 即不初始化，可读可写， 8（2^3）字节对齐。 __heap_base 表示对的起始地址， __heap_limit 表示堆的结束地址。堆是由低向高生长的，跟栈的生长方向相反。堆主要用来动态内存的分配，像 malloc() 函数申请的内存就在堆上面。这个在 STM32 里面用的比较少。?
PRESERVE8： 指定当前文件的堆栈按照 8 字节对齐。
THUMB： 表示后面指令兼容 THUMB 指令。 THUBM 是 ARM 以前的指令集， 16bit，现在 Cortex-M系列的都使用 THUMB-2 指令集， THUMB-2 是 32 位的，兼容 16 位和 32 位的指令，是 THUMB的超集。
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Heap_Size EQU 0x00000200 ;512B
AREA HEAP, NOINIT, READWRITE, ALIGN=3
__heap_base
Heap_Mem SPACE Heap_Size
__heap_limit
PRESERVE8
THUMB 复位程序
复位子程序是系统上电后第一个执行的程序，调用 SystemInit 函数初始化系统时钟，然后调用 C库函数 _mian，最终调用 main 函数去到 C 的世界。
WEAK：表示弱定义，如果外部文件优先定义了该标号则首先引用该标号，如果外部文件没有声明也不会出错。这里表示复位子程序可以由用户在其他文件重新实现，这里并不是唯一的。
IMPORT：表示该标号来自外部文件，跟 C 语言中的 EXTERN 关键字类似。这里表示 SystemInit和 __main 这两个函数均来自外部的文件。SystemInit() 是一个标准的库函数，在 system_stm32f10x.c 这个库文件总定义。主要作用是配置系统时钟，这里调用这个函数之后，单片机的系统时钟配被配置为 72M。__main 是一个标准的 C 库函数，主要作用是初始化用户堆栈，并在函数的最后调用 main 函数去到 C 的世界。这就是为什么我们写的程序都有一个 main 函数的原因。
Reset_Handler PROC
EXPORT Reset_Handler [WEAK] ;弱定义
IMPORT __main
IMPORT SystemInit ;初始化系统时钟，由用户定义
LDR R0, =SystemInit
BLX R0
LDR R0, =__main ;C库函数，实现堆栈的初始化和调用c里面的main函数
BX R0
ENDP?启动文件
汇编中“；”代表注释，c语言”//“代表注释
;******************** (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:
;* - 初始化堆栈指针SP
;* - 初始化PC指针
;* - 初始化中断向量表
;* - 配置系统时钟
;* - 调用C库函数_main，最终去到C的世界
;* 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.
;*******************************************************************************
;1-栈
; Amount of memory (in bytes) allocated for Stack
; Tailor this value to your application needs
; <h> 栈配置，用于变量，函数调用
; <o> Stack Size (in Bytes) <0x0-0xFFFFFFFF:8>
; </h>
Stack_Size EQU 0x00000400 ; 1KB
AREA STACK, NOINIT, READWRITE, ALIGN=3
Stack_Mem SPACE Stack_Size
__initial_sp
;2-堆
; <h> 堆配置，用于malloc等函数的动态内存分配
; <o> Heap Size (in Bytes) <0x0-0xFFFFFFFF:8>
; </h>
Heap_Size EQU 0x00000200 ;512B
AREA HEAP, NOINIT, READWRITE, ALIGN=3
__heap_base
Heap_Mem SPACE Heap_Size
__heap_limit
PRESERVE8 ;当前堆栈8字节对齐
THUMB ;兼容 THUMB 指令，老的指令，16bit，现在Cortex-M3的都是THUMB-2指令，兼容16/32位
;3-向量表，存的是中断服务函数的名称，即地址
; Vector Table Mapped to Address 0 at Reset，这里的0地址指的是FLASH的起始地址
AREA RESET, DATA, READONLY
EXPORT __Vectors
EXPORT __Vectors_End
EXPORT __Vectors_Size
__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
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
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_Size EQU __Vectors_End - __Vectors
AREA |.text|, CODE, READONLY
;4-复位程序，系统上电后第一个要执行的程序
; Reset handler
Reset_Handler PROC
EXPORT Reset_Handler [WEAK] ;弱定义
IMPORT __main
IMPORT SystemInit ;初始化系统时钟，由用户定义
LDR R0, =SystemInit
BLX R0
LDR R0, =__main ;C库函数，实现堆栈的初始化和调用c里面的main函数
BX R0
ENDP
;5-中断服务程序，全部为空，需要自己在C程序里面另外实现，但是函数名字必须跟这里的一样
;如果不一样，则会执行这里的中断服务函数，即无限循环，出现这样的错误很难发现
; Dummy Exception Handlers (infinite loops which can be modified)
NMI_Handler PROC
EXPORT NMI_Handler [WEAK]
B .
ENDP
HardFault_Handler\
PROC
EXPORT HardFault_Handler [WEAK]
B .
ENDP
MemManage_Handler\
PROC
EXPORT MemManage_Handler [WEAK]
B .
ENDP
BusFault_Handler\
PROC
EXPORT BusFault_Handler [WEAK]
B .
ENDP
UsageFault_Handler\
PROC
EXPORT UsageFault_Handler [WEAK]
B .
ENDP
SVC_Handler PROC
EXPORT SVC_Handler [WEAK]
B .
ENDP
DebugMon_Handler\
PROC
EXPORT DebugMon_Handler [WEAK]
B .
ENDP
PendSV_Handler PROC
EXPORT PendSV_Handler [WEAK]
B .
ENDP
SysTick_Handler PROC
EXPORT SysTick_Handler [WEAK]
B .
ENDP
Default_Handler PROC
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]
WWDG_IRQHandler
PVD_IRQHandler
TAMPER_IRQHandler
RTC_IRQHandler
FLASH_IRQHandler
RCC_IRQHandler
EXTI0_IRQHandler
EXTI1_IRQHandler
EXTI2_IRQHandler
EXTI3_IRQHandler
EXTI4_IRQHandler
DMA1_Channel1_IRQHandler
DMA1_Channel2_IRQHandler
DMA1_Channel3_IRQHandler
DMA1_Channel4_IRQHandler
DMA1_Channel5_IRQHandler
DMA1_Channel6_IRQHandler
DMA1_Channel7_IRQHandler
ADC1_2_IRQHandler
USB_HP_CAN1_TX_IRQHandler
USB_LP_CAN1_RX0_IRQHandler
CAN1_RX1_IRQHandler
CAN1_SCE_IRQHandler
EXTI9_5_IRQHandler
TIM1_BRK_IRQHandler
TIM1_UP_IRQHandler
TIM1_TRG_COM_IRQHandler
TIM1_CC_IRQHandler
TIM2_IRQHandler
TIM3_IRQHandler
TIM4_IRQHandler
I2C1_EV_IRQHandler
I2C1_ER_IRQHandler
I2C2_EV_IRQHandler
I2C2_ER_IRQHandler
SPI1_IRQHandler
SPI2_IRQHandler
USART1_IRQHandler
USART2_IRQHandler
USART3_IRQHandler
EXTI15_10_IRQHandler
RTCAlarm_IRQHandler
USBWakeUp_IRQHandler
TIM8_BRK_IRQHandler
TIM8_UP_IRQHandler
TIM8_TRG_COM_IRQHandler
TIM8_CC_IRQHandler
ADC3_IRQHandler
FSMC_IRQHandler
SDIO_IRQHandler
TIM5_IRQHandler
SPI3_IRQHandler
UART4_IRQHandler
UART5_IRQHandler
TIM6_IRQHandler
TIM7_IRQHandler
DMA2_Channel1_IRQHandler
DMA2_Channel2_IRQHandler
DMA2_Channel3_IRQHandler
DMA2_Channel4_5_IRQHandler
B .
ENDP
ALIGN
;6-用户堆栈初始化，由C库函数_main来完成
;*******************************************************************************
; User Stack and Heap initialization
;*******************************************************************************
IF :DEF:__MICROLIB ;这个宏在IDE里面配置
EXPORT __initial_sp
EXPORT __heap_base
EXPORT __heap_limit
ELSE
IMPORT __use_two_region_memory ;这个函数需要用户自己实现
EXPORT __user_initial_stackheap
__user_initial_stackheap ;
LDR R0, = Heap_Mem
LDR R1, =(Stack_Mem + Stack_Size)
LDR R2, = (Heap_Mem + Heap_Size)
LDR R3, = Stack_Mem
BX LR
ALIGN
ENDIF
END
;******************* (C) COPYRIGHT 2011 STMicroelectronics *****END OF FILE*****