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发布时间：2021-12-4 17:03
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STM32启动过程全面解析，包括启动过程的介绍、启动代码的陈列以及深入解析。相对于ARM上一代的主流ARM7/ARM9内核架构，新一代Cortex内核架构的 启动方式有了比较大的变化。ARM7/ARM9内核的控制器在复位后，CPU会从存储空间的绝对地址0x000000取出第一条指令执行复位中断服务程序的方式启动， 即固定了复位后的起始地址为0x000000（PC = 0x000000）同时中断向量表的位置并不是固定的。而Cortex-M3内核则正好相反，有3种情况： 1、 通过boot引脚设置可以将中断向量表定位于SRAM区，即起始地址为0x2000000，同时复位后PC指针位于0x2000000处; 2、 通过boot引脚设置可以将中断向量表定位于FLASH区，即起始地址为0x8000000，同时复位后PC指针位于0x8000000处;7 \" J+ U7 \/ \' X9 V Y) u ^ 3、 通过boot引脚设置可以将中断向量表定位于内置Bootloader区，本文不对这种情况做论述;! L x, h' m( i4 s2 _, [# D5 \) f Cortex-M3内核规定，起始地址必须存放堆顶指针，而第二个地址则必须存放复位中断入口向量地址，这样在Cortex-M3内核复位后，会自动从起始地址的7 Y8 _( ]+ U, u0 w 下一个32位空间取出复位中断入口向量，跳转执行复位中断服务程序。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& D5 Z4 R( a7 l D0 D 化的。3 V4 A5 I- [0 V5 ]0 O! x 有了上述准备只是后，下面以STM32的f2xx固件库提供的启动文件“startup_stm32f2xx.s”为模板，对STM32的启动过程做一个简要而全面的解析。 ;******************** (C) COPYRIGHT 2011 STMicroelectronics ******************** ;* File Name : startup_stm32f2xx.s# w+ q$ P5 a8 }6 \( B ;* Author : MCD Application Team! V8 d* d8 _4 R& M% |+ G ;* Version : V1.0.0( W7 @( f- [& p1 B+ P( p ;* Date : 18-April-2011 ;* Description : STM32F2xx devices vector table for MDK-ARM toolchain. ;* This module performs: ;* - Set the initial SP x+ ^) ?% w) B8 i2 \8 ~* D) `$ `) Q ;* - Set the initial PC == Reset_Handler4 r$ ]: Z! V$ z: n% s, W ;* - Set the vector table entries with the exceptions ISR address ;* - Branches to __main in the C library (which eventually0 y! F9 z9 S B3 K ;* calls main()).3 ~7 [5 Y8 P& C ;* After Reset the CortexM3 processor is in Thread mode, ;* priority is Privileged, and the Stack is set to Main.1 P: B' B. h6 h* [! q7 r Y7 L# _ ;* <<< Use Configuration Wizard in Context Menu >>> * L& ~; F6 p }% e' C& F2 N# p `" o ;******************************************************************************* ; THE PRESENT FIRMWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS/ s) P! W7 z' l/ A+ l ; WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE TIME.* l6 X, N7 Z9 [: F( b ; AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY DIRECT, ; INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING FROM THE8 L9 x2 `; J9 Z8 Z8 x, A& m ; CONTENT OF SUCH FIRMWARE AND/OR THE USE MADE BY CUSTOMERS OF THE CODING ; INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS. ;*******************************************************************************! L2 o) x [. L' ?: E- z ; Amount of memory (in bytes) allocated for Stack! G' b( S5 K- o! n( @' w; y ; Tailor this value to your application needs* L' t4 T+ S) g6 P$ P ; <h> Stack Configuration2 J( Z: s' S* d0 b2 X+ F3 H( v( j- | ; <o> Stack Size (in Bytes) <0x0-0xFFFFFFFF:8>6 o4 P, L' ~4 G( m: s5 l2 d8 q ; </h>7 L: V( J0 f: |% ^& `! A) i9 m9 C- i ! n: K( @5 c5 q/ l1 W y. E- j$ ] 2 U7 I0 S% _* B- W4 R z Stack_Size EQU 0x00000400 ;定义栈空间大小为0x00000400，此语句等价于C:#define Stack_Size 0x00000400 AREA STACK, NOINIT, READWRITE, ALIGN=3 ;定义栈，，可读写，8字节对齐 Stack_Mem SPACE Stack_Size ;开辟一段大小为Stack_Size的内存空间作为栈 __initial_sp ;标号__initial_sp，表示栈空间顶地址" J. p Z. V5 x+ i 6 W1 o; P2 F" g& x3 q5 c " e8 O, ^. k2 w/ ?# j' v2 q9 ~ 6 C3 M& @/ x- @ ; <h> Heap Configuration & I- w8 g' [- F9 N ; <o> Heap Size (in Bytes) <0x0-0xFFFFFFFF:8> ; </h>% F& ?9 v, Y# ?' e; e ~$ r' m( `5 Z Heap_Size EQU 0x00000200 ;定义堆空间大小为0x00000200个字节# m( M- ]0 J& q- v2 M AREA HEAP, NOINIT, READWRITE, ALIGN=3 ;定义堆，，可读写，8字节对齐 __heap_base ;标号__heap_base，表示堆空间起始地址 Heap_Mem SPACE Heap_Size ;开辟一段大小为Heap_Size的内存空间作为堆。 __heap_limit ;标号__heap_limit，表示堆空间结束地址 4 W8 d" w3 V0 \' @$ Y1 H z8 D( }! A PRESERVE8 ;告诉编译器以8字节对齐3 _; q$ P$ j+ P P F6 f2 r c* q4 l THUMB ;告诉编译器使用THUMB指令集 ( \3 |, b4 v3 o) n5 U& U2 f) _% y 9 m) A; N, r/ H' [$ p: G ; g# Z* M: G, m6 _. ^+ \/ v ; Vector Table Mapped to Address 0 at Reset 1 I. A/ W. K7 q# n) t 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）4 R7 h# Z, Z6 l) _( a% b) b EXPORT __Vectors ;将标号__Vectors声明为全局标号，这样外部文件就可以使用这个标号 EXPORT __Vectors_End ; EXPORT __Vectors_Size ;$ S+ H; T: q# ]2 a ;建立中断向量表! f) _& E3 Z* j' y* d' s0 U5 [, H __Vectors DCD __initial_sp ; Top of Stack,存放于FLASH中的0x8000000地址处 DCD Reset_Handler ; Reset Handler,存放于FLASH中的0x8000004地址处( P4 U% X: ^2 b, u) Z* U( C0 R DCD NMI_Handler ; NMI Handler DCD HardFault_Handler ; Hard Fault Handler DCD MemManage_Handler ; MPU Fault Handler DCD BusFault_Handler ; Bus Fault Handler+ g1 l! U; e" T3 S DCD UsageFault_Handler ; Usage Fault Handler4 j: X2 x" H# e& {$ q6 J) x" k% D DCD 0 ; Reserved) k+ t8 O V1 C q5 r DCD 0 ; Reserved DCD 0 ; Reserved DCD 0 ; Reserved DCD SVC_Handler ; SVCall Handler DCD DebugMon_Handler ; Debug Monitor Handler* z6 h- X& K) H) [/ c DCD 0 ; Reserved4 q) `; D6 c' y% B DCD PendSV_Handler ; PendSV Handler DCD SysTick_Handler ; SysTick Handler1 p, |% J. g# F5 L- @! k ; External Interrupts. I7 S8 E8 P+ @. {& w: f4 ? DCD WWDG_IRQHandler ; Window WatchDog DCD PVD_IRQHandler ; PVD through EXTI Line detection DCD TAMP_STAMP_IRQHandler ; Tamper and TimeStamps through the EXTI line DCD RTC_WKUP_IRQHandler ; RTC Wakeup through the EXTI line 2 V$ |# g& a! |+ x DCD FLASH_IRQHandler ; FLASH DCD RCC_IRQHandler ; RCC 8 F6 h6 O: S7 `' t Q' E DCD EXTI0_IRQHandler ; EXTI Line0 $ ]* k, S7 e( M% S DCD EXTI1_IRQHandler ; EXTI Line1 , j! a# x$ A" N# |+ L DCD EXTI2_IRQHandler ; EXTI Line2 DCD EXTI3_IRQHandler ; EXTI Line3 DCD EXTI4_IRQHandler ; EXTI Line4 , X) K3 b2 O5 A& {8 o( E DCD DMA1_Stream0_IRQHandler ; DMA1 Stream 0 ^+ z w0 C, m, { DCD DMA1_Stream1_IRQHandler ; DMA1 Stream 1 DCD DMA1_Stream2_IRQHandler ; DMA1 Stream 2 DCD DMA1_Stream3_IRQHandler ; DMA1 Stream 3 / z! V. c7 f* t3 ] DCD DMA1_Stream4_IRQHandler ; DMA1 Stream 4 DCD DMA1_Stream5_IRQHandler ; DMA1 Stream 5 & C) q2 g( @, X9 ?7 I8 x) e" Q" w DCD DMA1_Stream6_IRQHandler ; DMA1 Stream 6 DCD ADC_IRQHandler ; ADC1, ADC2 and ADC3s ) ^; c8 I$ E' Z. b" [: k DCD CAN1_TX_IRQHandler ; CAN1 TX DCD CAN1_RX0_IRQHandler ; CAN1 RX0 DCD CAN1_RX1_IRQHandler ; CAN1 RX1 DCD CAN1_SCE_IRQHandler ; CAN1 SCE : d+ @2 b: _: c# t. @5 y: F2 P" [ DCD EXTI9_5_IRQHandler ; External Line[9:5]s DCD TIM1_BRK_TIM9_IRQHandler ; TIM1 Break and TIM9 DCD TIM1_UP_TIM10_IRQHandler ; TIM1 Update and TIM10 DCD TIM1_TRG_COM_TIM11_IRQHandler ; TIM1 Trigger and Commutation and TIM113 Y" X4 |. r3 j9 @; ?; X) M% ] DCD TIM1_CC_IRQHandler ; TIM1 Capture Compare # U: w) a. L$ R8 i9 S DCD TIM2_IRQHandler ; TIM2 DCD TIM3_IRQHandler ; TIM3 5 v' c3 \4 I1 W- @( k4 q* g: R6 \ DCD TIM4_IRQHandler ; TIM4 9 p4 V. E( _) Z8 l% _ DCD I2C1_EV_IRQHandler ; I2C1 Event DCD I2C1_ER_IRQHandler ; I2C1 Error DCD I2C2_EV_IRQHandler ; I2C2 Event " a4 A+ g0 J/ A; N DCD I2C2_ER_IRQHandler ; I2C2 Error % z1 f& U k0 |& ^ DCD SPI1_IRQHandler ; SPI1 DCD SPI2_IRQHandler ; SPI2 DCD USART1_IRQHandler ; USART1 DCD USART2_IRQHandler ; USART2 DCD USART3_IRQHandler ; USART3 DCD EXTI15_10_IRQHandler ; External Line[15:10]s DCD RTC_Alarm_IRQHandler ; RTC Alarm (A and B) through EXTI Line 3 t- L7 @% P' t+ y: Q i( w0 O6 y DCD OTG_FS_WKUP_IRQHandler ; USB OTG FS Wakeup through EXTI line 6 @' Z8 D9 q1 L. t- Y' p DCD TIM8_BRK_TIM12_IRQHandler ; TIM8 Break and TIM12 # h0 J" K5 ]7 @# o h5 [$ X DCD TIM8_UP_TIM13_IRQHandler ; TIM8 Update and TIM13 1 O; L o2 F6 U* v0 Q5 t& z: w DCD TIM8_TRG_COM_TIM14_IRQHandler ; TIM8 Trigger and Commutation and TIM14 DCD TIM8_CC_IRQHandler ; TIM8 Capture Compare 3 t- T R# }" c+ u0 | DCD DMA1_Stream7_IRQHandler ; DMA1 Stream7 : g- h' t' s* ?. f3 L9 e! g DCD FSMC_IRQHandler ; FSMC DCD SDIO_IRQHandler ; SDIO : p w% q0 b- w8 l0 X DCD TIM5_IRQHandler ; TIM5 DCD SPI3_IRQHandler ; SPI3 2 w0 O3 `; B" Y! g DCD UART4_IRQHandler ; UART4 5 B4 `; Y) m( d6 d1 s* A* @1 m DCD UART5_IRQHandler ; UART5 # F: g8 @1 T& e8 D4 l) ` DCD TIM6_DAC_IRQHandler ; TIM6 and DAC1&2 underrun errors DCD TIM7_IRQHandler ; TIM7 1 }! i/ _5 {2 r8 ~ DCD DMA2_Stream0_IRQHandler ; DMA2 Stream 0 , c6 S9 d3 v% U DCD DMA2_Stream1_IRQHandler ; DMA2 Stream 1 DCD DMA2_Stream2_IRQHandler ; DMA2 Stream 2 DCD DMA2_Stream3_IRQHandler ; DMA2 Stream 3 5 U9 H6 a! t# z) j$ }3 ^ DCD DMA2_Stream4_IRQHandler ; DMA2 Stream 4 $ y4 c' o7 L# Q$ k( ^5 J DCD ETH_IRQHandler ; Ethernet 4 _, H# N9 a5 G% F DCD ETH_WKUP_IRQHandler ; Ethernet Wakeup through EXTI line DCD CAN2_TX_IRQHandler ; CAN2 TX DCD CAN2_RX0_IRQHandler ; CAN2 RX0 DCD CAN2_RX1_IRQHandler ; CAN2 RX1 DCD CAN2_SCE_IRQHandler ; CAN2 SCE 0 v2 k( j, N0 D: T, d. j. D DCD OTG_FS_IRQHandler ; USB OTG FS DCD DMA2_Stream5_IRQHandler ; DMA2 Stream 5 DCD DMA2_Stream6_IRQHandler ; DMA2 Stream 6 / b# _' h. K$ \+ W' U DCD DMA2_Stream7_IRQHandler ; DMA2 Stream 7 ! A( E! t% d. O* M6 G DCD USART6_IRQHandler ; USART6 4 c' O& Q; p. X$ O+ [ DCD I2C3_EV_IRQHandler ; I2C3 event DCD I2C3_ER_IRQHandler ; I2C3 error I( Z5 ~/ S0 A* k DCD OTG_HS_EP1_OUT_IRQHandler ; USB OTG HS End Point 1 Out DCD OTG_HS_EP1_IN_IRQHandler ; USB OTG HS End Point 1 In ; E& U2 H4 H0 @: f6 n& y DCD OTG_HS_WKUP_IRQHandler ; USB OTG HS Wakeup through EXTI * v# U0 Z- c; b; ^; B% H+ W% u! F* ^ DCD OTG_HS_IRQHandler ; USB OTG HS ; y+ `" R" s. p2 j: Z# W0 H DCD DCMI_IRQHandler ; DCMI ' E; ]1 h7 f% y& l+ i5 I$ k8 C DCD CRYP_IRQHandler ; CRYP crypto , g4 ^& F4 z) ]2 S- Y DCD HASH_RNG_IRQHandler ; Hash and Rng __Vectors_End __Vectors_Size EQU __Vectors_End - __Vectors AREA |.text|, CODE, READONLY ;只读代码段4 K! {/ t) a6 D) z @ B/ \4 Y ; Reset handler Reset_Handler PROC ;复位中断服务程序，PROC…ENDP结构表示程序的开始和结束% |& I2 h* n$ x8 K EXPORT Reset_Handler [WEAK] ;声明复位中断向量Reset_Handler为全局属性，这样外部文件就可以调用此复位中断服务& o0 x+ e2 d" k0 I' Z/ T* j5 I IMPORT SystemInit ;声明SystemInit标号 IMPORT __main ;声明__main标号 LDR R0, =SystemInit ;跳转到SystemInit地址执行 BLX R0 ;" C( M7 R! u8 {, E5 w LDR R0, =__main ;跳转__main地址执行3 X8 r4 [7 w# c% d" Y$ S: c8 w BX R07 Z7 e2 ]3 ?: S5 ] ENDP " H7 H( D( X0 [9 k7 q) E3 l ; Dummy Exception Handlers (infinite loops which can be modified)8 n7 M8 r. A# B2 z$ z # G+ S5 p# _) S8 g NMI_Handler PROC EXPORT NMI_Handler [WEAK] h; T3 y5 a- ] ^+ K( d) G B . ENDP& B' g& e( j8 U. V HardFault_Handler\ PROC EXPORT HardFault_Handler [WEAK]5 D' {. e1 |* Q$ x7 X' w- k B . ENDP MemManage_Handler\( V8 b7 r$ r; Z) y PROC/ u: q+ ~% f. s3 y2 ` EXPORT MemManage_Handler [WEAK]0 A9 X+ g1 `; ]! l' Q6 R B .6 G; |, Z* [, b0 t8 F! z) D$ J( f ENDP" i6 A; Q6 V4 p" }0 U BusFault_Handler\1 }9 X% F/ o) Y2 C* O: J PROC EXPORT BusFault_Handler [WEAK]% E* {& X" V& K5 M B .% o" S `, A7 O" Q# \, g ENDP6 M# | d5 I. L: u# \8 Y$ X8 W UsageFault_Handler\9 E9 y( G$ w% ]2 n# L3 c PROC EXPORT UsageFault_Handler [WEAK]6 g+ l$ H8 X/ x) C B . ENDP/ K8 @0 V. B& O+ \" @. i" p SVC_Handler PROC EXPORT SVC_Handler [WEAK] A) N+ @6 F2 E# k, O9 D B . ENDP! N; \# C0 h# @/ o DebugMon_Handler\) x3 t# R _3 @( Q PROC EXPORT DebugMon_Handler [WEAK]! f( U1 b; |( `% h& R B .4 J# L. E( W5 T p* P9 ^1 Z0 W; m ENDP PendSV_Handler PROC EXPORT PendSV_Handler [WEAK] B . ENDP& n# K" g) K5 l- `+ D# V SysTick_Handler PROC/ |% T7 q3 f: S# [+ C3 ~- b# Z EXPORT SysTick_Handler [WEAK] B . ENDP% }% u/ d. X M2 |' m3 R( k- s 1 ]8 T! e5 u( }, @5 }4 W) a Default_Handler PROC* ]" F+ l- P1 T5 L! d- G/ F3 } ) c2 q# ~3 j3 C q* v$ ^ EXPORT WWDG_IRQHandler [WEAK] " e$ |/ [0 U/ P+ G- R2 I7 X EXPORT PVD_IRQHandler [WEAK] EXPORT TAMP_STAMP_IRQHandler [WEAK] EXPORT RTC_WKUP_IRQHandler [WEAK] EXPORT FLASH_IRQHandler [WEAK] 9 z. ]4 p1 y- v Y+ A- t0 o6 \ EXPORT RCC_IRQHandler [WEAK] - r, X+ S' e1 y& F) U8 k, B9 N EXPORT EXTI0_IRQHandler [WEAK] EXPORT EXTI1_IRQHandler [WEAK] ( F( V5 `/ D5 Z3 a! I EXPORT EXTI2_IRQHandler [WEAK] EXPORT EXTI3_IRQHandler [WEAK] / o1 r4 y2 W6 R$ y1 N9 C EXPORT EXTI4_IRQHandler [WEAK] I8 \% B# G6 V: d1 d EXPORT DMA1_Stream0_IRQHandler [WEAK] 0 b$ j9 I" a* ?; u EXPORT DMA1_Stream1_IRQHandler [WEAK] EXPORT DMA1_Stream2_IRQHandler [WEAK] EXPORT DMA1_Stream3_IRQHandler [WEAK] 4 F/ d2 p% e: f+ E: l; T# X: t EXPORT DMA1_Stream4_IRQHandler [WEAK] EXPORT DMA1_Stream5_IRQHandler [WEAK] EXPORT DMA1_Stream6_IRQHandler [WEAK] 9 K' q& ^( @1 d; s" C. D$ ^ EXPORT ADC_IRQHandler [WEAK] * u$ ~0 x g" s; r% [' p, [) I EXPORT CAN1_TX_IRQHandler [WEAK] EXPORT CAN1_RX0_IRQHandler [WEAK] % @; a' b1 f3 y8 V* H; w EXPORT CAN1_RX1_IRQHandler [WEAK] 3 S# l6 l6 @% ~) P1 b EXPORT CAN1_SCE_IRQHandler [WEAK] EXPORT EXTI9_5_IRQHandler [WEAK] EXPORT TIM1_BRK_TIM9_IRQHandler [WEAK] EXPORT TIM1_UP_TIM10_IRQHandler [WEAK] EXPORT TIM1_TRG_COM_TIM11_IRQHandler [WEAK] " U7 o+ r2 o/ Q& k _' ?, Z5 R EXPORT TIM1_CC_IRQHandler [WEAK] EXPORT TIM2_IRQHandler [WEAK] EXPORT TIM3_IRQHandler [WEAK] 0 ]0 M1 ^, I; i$ Y EXPORT TIM4_IRQHandler [WEAK] EXPORT I2C1_EV_IRQHandler [WEAK] EXPORT I2C1_ER_IRQHandler [WEAK] 3 C2 c! p7 ^7 A4 r: R EXPORT I2C2_EV_IRQHandler [WEAK] EXPORT I2C2_ER_IRQHandler [WEAK] EXPORT SPI1_IRQHandler [WEAK] EXPORT SPI2_IRQHandler [WEAK] ( d$ ~# M( A# F v EXPORT USART1_IRQHandler [WEAK] EXPORT USART2_IRQHandler [WEAK] ( e3 U% x" |9 U+ O4 O+ B& Y EXPORT USART3_IRQHandler [WEAK] EXPORT EXTI15_10_IRQHandler [WEAK] EXPORT RTC_Alarm_IRQHandler [WEAK] # K2 V9 j, l" {3 J& \1 F6 b EXPORT OTG_FS_WKUP_IRQHandler [WEAK] EXPORT TIM8_BRK_TIM12_IRQHandler [WEAK] 4 V' n, U( F# A6 @# R6 A% I2 C EXPORT TIM8_UP_TIM13_IRQHandler [WEAK] EXPORT TIM8_TRG_COM_TIM14_IRQHandler [WEAK] 9 L. L1 N% W! x, b4 x c EXPORT TIM8_CC_IRQHandler [WEAK] EXPORT DMA1_Stream7_IRQHandler [WEAK] ; |" }' r9 C: s y% ~0 c P: _ EXPORT FSMC_IRQHandler [WEAK] EXPORT SDIO_IRQHandler [WEAK] EXPORT TIM5_IRQHandler [WEAK] EXPORT SPI3_IRQHandler [WEAK] / w& E7 ]6 D' r5 @- p b2 `$ t EXPORT UART4_IRQHandler [WEAK] ) u" U7 Q' d/ b2 T0 z EXPORT UART5_IRQHandler [WEAK] EXPORT TIM6_DAC_IRQHandler [WEAK] & H7 Q5 _+ l ~9 o EXPORT TIM7_IRQHandler [WEAK] ; s5 c4 @* ]3 K4 L% w1 k2 h* O+ o9 I EXPORT DMA2_Stream0_IRQHandler [WEAK] EXPORT DMA2_Stream1_IRQHandler [WEAK] EXPORT DMA2_Stream2_IRQHandler [WEAK] 5 G0 w- ?# Q- \( R0 Q' y EXPORT DMA2_Stream3_IRQHandler [WEAK] ; U8 A8 [8 x3 [$ c2 F5 ]# D& z$ S& P EXPORT DMA2_Stream4_IRQHandler [WEAK] EXPORT ETH_IRQHandler [WEAK] ) s0 z. n5 G4 W) i EXPORT ETH_WKUP_IRQHandler [WEAK] * G9 Y8 Z1 J" k+ }7 u- U- U EXPORT CAN2_TX_IRQHandler [WEAK] EXPORT CAN2_RX0_IRQHandler [WEAK] EXPORT CAN2_RX1_IRQHandler [WEAK] 3 b, K$ \& P, k& M" y) ]6 v7 ~ EXPORT CAN2_SCE_IRQHandler [WEAK] EXPORT OTG_FS_IRQHandler [WEAK] ( N% G5 X% C8 X- A U/ V1 e EXPORT DMA2_Stream5_IRQHandler [WEAK] 4 m1 Q$ k3 ]$ R. i, G EXPORT DMA2_Stream6_IRQHandler [WEAK] EXPORT DMA2_Stream7_IRQHandler [WEAK] 6 S" g# p1 x: |- ^- t EXPORT USART6_IRQHandler [WEAK] EXPORT I2C3_EV_IRQHandler [WEAK] * V) b X' `4 }. n% f EXPORT I2C3_ER_IRQHandler [WEAK] EXPORT OTG_HS_EP1_OUT_IRQHandler [WEAK] ! ?+ k/ E# f5 L7 T2 P2 L# w EXPORT OTG_HS_EP1_IN_IRQHandler [WEAK] EXPORT OTG_HS_WKUP_IRQHandler [WEAK] , g l" c4 I8 \0 K7 H EXPORT OTG_HS_IRQHandler [WEAK] EXPORT DCMI_IRQHandler [WEAK] & Q6 y3 C5 J+ _% T! F2 v0 Z Z EXPORT CRYP_IRQHandler [WEAK] % Y( ]' @. n4 [+ j: b EXPORT HASH_RNG_IRQHandler [WEAK] WWDG_IRQHandler PVD_IRQHandler TAMP_STAMP_IRQHandler ' P0 l0 I, c7 h8 K* c% ^ RTC_WKUP_IRQHandler FLASH_IRQHandler , d* w/ n8 E! y$ i9 ?/ Z* e RCC_IRQHandler + b9 G4 n% \( F1 E# U EXTI0_IRQHandler EXTI1_IRQHandler EXTI2_IRQHandler EXTI3_IRQHandler , i$ V, T' x5 N- p+ L EXTI4_IRQHandler % I$ z+ j; h1 R5 D) q6 f2 o DMA1_Stream0_IRQHandler 9 E r4 q4 @$ v' @. k DMA1_Stream1_IRQHandler 2 T. h0 c; j1 V% m: x; u: F/ g DMA1_Stream2_IRQHandler DMA1_Stream3_IRQHandler DMA1_Stream4_IRQHandler # h8 F' L" W; w7 K5 l0 ^; o DMA1_Stream5_IRQHandler " b9 u B @) V- |3 S8 C0 K( z DMA1_Stream6_IRQHandler ADC_IRQHandler CAN1_TX_IRQHandler . L E4 r& o4 T+ U. o8 s( P' r CAN1_RX0_IRQHandler ! x6 J& z% {& s- e) R CAN1_RX1_IRQHandler CAN1_SCE_IRQHandler EXTI9_5_IRQHandler TIM1_BRK_TIM9_IRQHandler TIM1_UP_TIM10_IRQHandler TIM1_TRG_COM_TIM11_IRQHandler TIM1_CC_IRQHandler TIM2_IRQHandler 1 i S- h; p6 ^6 E TIM3_IRQHandler / I0 P+ s: S4 d+ d9 o TIM4_IRQHandler ( i o1 D$ C8 z5 E% c I2C1_EV_IRQHandler 2 d7 F" s6 g9 \& n1 x) W I2C1_ER_IRQHandler I2C2_EV_IRQHandler 9 L% T& J' o2 z6 T8 q I2C2_ER_IRQHandler SPI1_IRQHandler SPI2_IRQHandler + F4 | P6 D x3 [& ]4 R8 `- q USART1_IRQHandler 8 ^5 {; }; `; R( {9 H5 v% \ USART2_IRQHandler USART3_IRQHandler + b8 M# l8 a1 ]# d' P) ~ EXTI15_10_IRQHandler RTC_Alarm_IRQHandler $ W7 g# x* I. a) R0 z5 {7 I! V3 E OTG_FS_WKUP_IRQHandler TIM8_BRK_TIM12_IRQHandler TIM8_UP_TIM13_IRQHandler . J( N5 }8 y; N: @3 R/ c TIM8_TRG_COM_TIM14_IRQHandler TIM8_CC_IRQHandler DMA1_Stream7_IRQHandler , A- \% O9 @# v4 J0 O; C2 @ FSMC_IRQHandler 9 M9 p# R0 f& i8 e' z9 I4 v) t SDIO_IRQHandler TIM5_IRQHandler SPI3_IRQHandler & b8 R) s3 e: j6 @ E) W# K2 u UART4_IRQHandler UART5_IRQHandler 3 G% F1 x( U1 E+ x+ k! V TIM6_DAC_IRQHandler TIM7_IRQHandler DMA2_Stream0_IRQHandler ) B& r0 d& v* v: E) d D& { DMA2_Stream1_IRQHandler DMA2_Stream2_IRQHandler DMA2_Stream3_IRQHandler DMA2_Stream4_IRQHandler ETH_IRQHandler : X) K: i! a0 Q) l6 J, E1 I# z ETH_WKUP_IRQHandler # j9 K5 A% O& ~5 s6 A, r CAN2_TX_IRQHandler CAN2_RX0_IRQHandler CAN2_RX1_IRQHandler - h& C& ~& \* w( g CAN2_SCE_IRQHandler OTG_FS_IRQHandler DMA2_Stream5_IRQHandler ; X: D- x7 f3 g% R3 ?1 J DMA2_Stream6_IRQHandler ( h3 Y5 |( ]5 _ DMA2_Stream7_IRQHandler $ B9 P6 R6 {4 I USART6_IRQHandler I2C3_EV_IRQHandler ; e, N9 q2 g& E* s0 n I2C3_ER_IRQHandler 1 V9 `. \' f5 t, v" G5 t( ]4 b OTG_HS_EP1_OUT_IRQHandler 4 F7 L4 |) ]( g, u# |! u OTG_HS_EP1_IN_IRQHandler OTG_HS_WKUP_IRQHandler f' g& @0 m0 K8 K6 j OTG_HS_IRQHandler DCMI_IRQHandler % ^/ q% ^% f; S1 }1 }9 W( L CRYP_IRQHandler % ], Q! |' K) W5 y4 |( H3 b HASH_RNG_IRQHandler ) ^6 k; i8 ?" b* z9 F2 L' t B . 0 g v2 R+ Y+ D ENDP% }: k- q- a8 {( S + j7 \ {8 E& n: i7 Z ALIGN |+ W; a6 q9 N( i2 h) c6 |4 \/ R ) ~. ]# Z& O4 |" }- p ;******************************************************************************* ; User Stack and Heap initialization ;******************************************************************************** T9 I- q& ]# l: O$ S( k! L IF  EF:__MICROLIB ;IF…ELSE…ENDIF结构，判断是否使用DEF：__MICROLIB（此处为不使用）EXPORT __initial_sp ;若使用DEF：__MICROLIB，则将__initial_sp，__heap_base，__heap_limit亦即栈顶地址，堆始末地址赋予全局属性，使外部程序可以使用1 o4 v3 V6 b8 M/ l EXPORT __heap_base EXPORT __heap_limit / M& I2 [! _8 V9 d ELSE6 {1 m! F7 v, e* C+ S, w/ I, e6 Y 9 z, `" ^# X: Z1 @9 Q# S) |/ O4 O IMPORT __use_two_region_memory ;定义全局标号__use_two_region_memory% S# s9 o; b8 ` [% x EXPORT __user_initial_stackheap ;声明全局标号__user_initial_stackheap，这样外程序也可调用此标号 % @$ G& {, w7 a& [" @3 y __user_initial_stackheap ;标号__user_initial_stackheap，表示用户堆栈初始化程序入口 4 ?( G5 Q5 v. k* w' S) D5 S# Y LDR R0, = Heap_Mem ;分别保存栈顶指针和栈大小，堆始地址和堆大小至R0，R1，R2，R3寄存器0 | k, f9 ?# e/ `) [, e LDR R1, =(Stack_Mem + Stack_Size)7 D% o8 A ]. A& F LDR R2, = (Heap_Mem + Heap_Size)8 Q; X5 z! h/ s* C: J, y3 a LDR R3, = Stack_Mem& p: j" Y! j5 k BX LR 3 j+ H& j+ K8 F5 o! h4 s; j8 [ ALIGN( R/ y/ T8 `: a+ h7 t; E: R7 D ENDIF . o# w5 l" B( l! V END ;程序完毕1 P* `* N% O, B# m ;******************* (C) COPYRIGHT 2011 STMicroelectronics *****END OF FILE***** 以上便是STM32的启动代码的完整解析，接下来对几个小地方做解释：, Y: |, C) ], D1 } P' N4 H 1、 AREA指令：伪指令，用于定义代码段或数据段，后跟属性标号。其中比较重要的一个标号为“READONLY”或者“READWRITE”，其中 “READONLY”表示该段为只读属性， 联系到STM32的内部存储介质，可知具有只读属性的段保存于FLASH区，即0x8000000地址后。而 “READONLY”表示该段为“可读写”属性，可知“可读写”段保存于SRAM 区，即0x2000000地址后。由此可以从第43、54行代码知道，堆栈段位于SRAM空间。从第64行可知，中断向量表放置与FLASH区，而这也是整片启动代码中最先被放进& g0 R# l* t7 z! o' ` [2 Y FLASH区的数据。因此可以得到一条重要的信息：0x8000000地址存放的是栈顶地址__initial_sp，0x8000004地址存放的是复位中断向量 Reset_Handler（STM32使 用32位总线，因此存储空间为4字节对齐）。5 H& v) ~: h: E7 l 2、 DCD指令：作用是开辟一段空间，其意义等价于C语言中的地址符“&”。因此从第69行开始建立的中断向量表则类似于使用C语言定义了一个指针数组，其每一个成员 都是一个函数指针，分别指向各个中断服务函数。 3、 标号：前文多处使用了“标号”一词。标号主要用于表示一片内存空间的某个位置，等价于C语言中的“地址”概念。地址仅仅表示存储空间的一个位置，从C语言的角 度来看，变量的地址，数组的地址或是函数的入口地址在本质上并无区别。 4、 第178行中的__main标号并不表示C程序中的main函数入口地址，因此第181行也并不是跳转至main函数开始执行C程序。__main标号表示C/C++标准实时库函数里的 一个初始化子程序__main的入口地址。该程序的一个主要作用是初始化堆栈（对于程序清单一来说则是跳转 __user_initial_stackheap标号进行初始化堆栈的），' s! |' k+ h' `$ |, \' C 并初始化映像文件，最后跳转C程序中的main函数。这就解释了为何所有的C 程序必须有一个main函数作为程序的起点——因为这是由C/C++标准实时库所规定的——并 且不能更改，因为C/C++标准实时库并不对外界开放源代码。因此，实际上在用户可见的前提下，程序在第182行后就跳转至.c文件中的main函数，开始执行C程序了。2 u! b7 W. S$ T: A! M 至此可以总结一下STM32的启动文件和启动过程。首先对栈和堆的大小进行定义，并在代码区的起始处建立中断向量表，其第一个表项是栈顶地址，第二个表项是复位 中断服务入口地址。然后在复位中断服务程序中跳转到C/C++标准实时库的__main函数，完成用户堆栈等的初始化后，跳转.c文件中的 main函数开始执行C程序。假设 STM32被设置为从内部FLASH启动（这也是最常见的一种情况），中断向量表起始地位为0x8000000，则栈顶地址存放于0x8000000处，而复位中断服务入口地址存放于+ t S+ E+ E2 d* e 0x8000004处。当STM32遇到复位信号后，则从0x80000004处取出复位中断服务入口地址，继而执行复位中断服务程序，然后跳转__main函数，最后进入mian函数，来( L$ S" B1 E' `) z1 L: G: ^9 A! j! c 到C的世界。+ F, y. e0 P/ P 注：+ B$ F* q) q3 ]* q, ~ 1.数据定义（ Data Definition ）伪指令 数据定义伪指令一般用于为特定的数据分配存储单元，同时可完成已分配存储单元的初始化。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。 语法格式：% R1 C6 |4 V" N& J+ M! y7 G( i 标号 DCD （或 DCDU ） 表达式% R- Q2 D) o. y m* @& F$ Z& A G DCD （或 DCDU ）伪指令用于分配一片连续的字存储单元并用伪指令中指定的表达式初始化。其中，表达式可以为程序标号或数字表达式。 DCD 也可用 “ & ” 代替。 用 DCD 分配的字存储单元是字对齐的，而用 DCDU 分配的字存储单元并不严格字对齐。 " k R; ?1 D! \; K- i, O ! ]. o2 e5 z* n 1 O2 G& Z9 J" @% c2 }5 j |
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