STM32 启动代码分析

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  本文作为本人csdn blog的主站的备份。（BlogID=028）

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环境说明

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前言

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STM32 启动代码分析

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  对于keil的启动代码（针对STM32F042），添加 备注 和 自己的理解

;******************** (C) COPYRIGHT 2014 STMicroelectronics ********************
;* File Name          : startup_stm32f042.s
;* Author             : MCD Application Team,modified by Sky,
;* Version            : V1.5.0
;* Date               : 05-December-2014,modified on,01-Nov-2016
;* Description        : STM32F042 Devices vector table for
;*                      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 system clock
;*                      - Branches to __main in the C library (which eventually
;*                        calls main()).
;*                      After Reset the CortexM0 processor is in Thread mode,
;*                      priority is Privileged, and the Stack is set to Main.
;* <<< Use Configuration Wizard in Context Menu >>>
;*******************************************************************************
;  @attention
;
;  Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
;  You may not use this file except in compliance with the License.
;  You may obtain a copy of the License at:
;
;         http:;;www.st.com/software_license_agreement_liberty_v2
;
;  Unless required by applicable law or agreed to in writing, software
;  distributed under the License is distributed on an "AS IS" BASIS,
;  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
;  See the License for the specific language governing permissions and
;  limitations under the License.
;
;*******************************************************************************

;
;
;notes:stack,heap,data seg,code seg address of mem is set by compiler
;
;

;
; Amount of memory (in bytes) allocated for Stack
; Tailor this value to your application needs
; <h> Stack Configuration
;   <o> Stack Size (in Bytes) <0x0-0xFFFFFFFF:8>
; </h>\

;;EQU 定义宏
;;栈大小，1k
Stack_Size      EQU     0x00000400
;;AREA 定义段，注意：一个程序是由多个段构成，如CODE，STACK，DATA，
;;ALIGN=3,8字节对齐
                AREA    STACK, NOINIT, READWRITE, ALIGN=3
Stack_Mem       SPACE   Stack_Size
;;__initial_sp一个标号,由汇编器进行计算，代表上面SPACE分配内存的最后一个地址，栈为向下增长型
__initial_sp

; <h> Heap Configuration
;   <o>  Heap Size (in Bytes) <0x0-0xFFFFFFFF:8>
; </h>
;;堆512bytes
Heap_Size       EQU     0x00000200

                AREA    HEAP, NOINIT, READWRITE, ALIGN=3
__heap_base
Heap_Mem        SPACE   Heap_Size
__heap_limit
;;PRESERVE8,指定当前文件堆栈8bytes对齐
                PRESERVE8
;;THUMB，后面的指令要兼容THUMB指令
                THUMB

; Vector Table Mapped to Address 0 at Reset
;;定义一个叫做RESET的数据段
                AREA    RESET, DATA, READONLY
;;EXPORT声明标号为外部文件可用
                EXPORT  __Vectors
                EXPORT  __Vectors_End
                EXPORT  __Vectors_Size
;;DCD是按4字节分配存储单元
__Vectors       DCD     __initial_sp                   ; Top of Stack
                        DCD     Reset_Handler                  ; Reset Handler
                        DCD     NMI_Handler                    ; NMI Handler
                        DCD     HardFault_Handler              ; Hard Fault Handler
                        DCD     0                              ; Reserved
                        DCD     0                              ; Reserved
                        DCD     0                              ; Reserved
                        DCD     0                              ; Reserved
                        DCD     0                              ; Reserved
                        DCD     0                              ; Reserved
                        DCD     0                              ; Reserved
                        DCD     SVC_Handler                    ; SVCall Handler
                        DCD     0                              ; Reserved
                        DCD     0                              ; Reserved
                        DCD     PendSV_Handler                 ; PendSV Handler
                        DCD     SysTick_Handler                ; SysTick Handler

                ; External Interrupts
                DCD     WWDG_IRQHandler                ; Window Watchdog
                DCD     PVD_VDDIO2_IRQHandler          ; PVD and VDDIO2 through EXTI Line detect
                DCD     RTC_IRQHandler                 ; RTC through EXTI Line
                DCD     FLASH_IRQHandler               ; FLASH
                DCD     RCC_CRS_IRQHandler             ; RCC and CRS
                DCD     EXTI0_1_IRQHandler             ; EXTI Line 0 and 1
                DCD     EXTI2_3_IRQHandler             ; EXTI Line 2 and 3
                DCD     EXTI4_15_IRQHandler            ; EXTI Line 4 to 15
                DCD     TSC_IRQHandler                 ; TS
                DCD     DMA1_Channel1_IRQHandler       ; DMA1 Channel 1
                DCD     DMA1_Channel2_3_IRQHandler     ; DMA1 Channel 2 and Channel 3
                DCD     DMA1_Channel4_5_IRQHandler     ; DMA1 Channel 4, Channel 5
                DCD     ADC1_IRQHandler                ; ADC1
                DCD     TIM1_BRK_UP_TRG_COM_IRQHandler ; TIM1 Break, Update, Trigger and Commutation
                DCD     TIM1_CC_IRQHandler             ; TIM1 Capture Compare
                DCD     TIM2_IRQHandler                ; TIM2
                DCD     TIM3_IRQHandler                ; TIM3
                DCD     0                              ; Reserved
                DCD     0                              ; Reserved
                DCD     TIM14_IRQHandler               ; TIM14
                DCD     0                              ; Reserved
                DCD     TIM16_IRQHandler               ; TIM16
                DCD     TIM17_IRQHandler               ; TIM17
                DCD     I2C1_IRQHandler                ; I2C1
                DCD     0                              ; Reserved
                DCD     SPI1_IRQHandler                ; SPI1
                DCD     SPI2_IRQHandler                ; SPI2
                DCD     USART1_IRQHandler              ; USART1
                DCD     USART2_IRQHandler              ; USART2
                DCD     0                              ; Reserved
                DCD     CEC_CAN_IRQHandler             ; CEC and CAN
                DCD     USB_IRQHandler                 ; USB

__Vectors_End

__Vectors_Size  EQU  __Vectors_End - __Vectors

;;定义一个.text的代码段
                AREA    |.text|, CODE, READONLY

;STM32F03x devices feature 4Kbytes of static SRAM. STM32F04x devices feature
;6 Kbytes of static SRAM. STM32F05x devices feature 8Kbytes of static SRAM.
;STM32F07xS devices feature 16 Kbytes of static SRAM. STM32F09x devices feature
;32 Kbytes of static SRAM.

; Reset handler routine
;;PROC定义子程序
Reset_Handler    PROC
;;WEAK:弱定义
                 EXPORT  Reset_Handler                 [WEAK]
        IMPORT  __main
        IMPORT  SystemInit

;;给R0赋值，sp的值
        LDR     R0, =__initial_sp          ; set stack pointer
;;R0给MSP寄存器
        MSR     MSP, R0  

;;Check if boot space corresponds to test memory 

        LDR R0,=0x00000004
        LDR R1, [R0]
		;;R1=0x08000004 OR R1=0x20000004 OR R1=0x1FXX XXXX
		;;when R1=R1=0x1FXX XXXX,we can know that Reset_Handler'sAddress is not right,
		;;it maybe in reserved or systemmemory or optionbyte，we must remap address for start
;;Logical shift right by register LSRS

        LSRS R1, R1, #24
		;R2=0x0000001F
        LDR R2,=0x1F
        CMP R1, R2

        BNE ApplicationStart  

;; SYSCFG clock enable
     ;RCC_APB2ENR,0x40021018
        LDR R0,=0x40021018
        LDR R1,=0x00000001
        STR R1, [R0]

;; Set CFGR1 register with flash memory remap at address 0
     ;SYS_CFGR1,0x40010000
        LDR R0,=0x40010000
        LDR R1,=0x00000000
        STR R1, [R0]
ApplicationStart
                 LDR     R0, =SystemInit
                 BLX     R0
                 LDR     R0, =__main
                 BX      R0
                 ENDP

; Dummy Exception Handlers (infinite loops which can be modified)

NMI_Handler     PROC
                EXPORT  NMI_Handler                    [WEAK]
					;;B .   无限循环
                B       .
                ENDP
HardFault_Handler\
                PROC
                EXPORT  HardFault_Handler              [WEAK]
                B       .
                ENDP
SVC_Handler     PROC
                EXPORT  SVC_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_VDDIO2_IRQHandler          [WEAK]
                EXPORT  RTC_IRQHandler                 [WEAK]
                EXPORT  FLASH_IRQHandler               [WEAK]
                EXPORT  RCC_CRS_IRQHandler             [WEAK]
                EXPORT  EXTI0_1_IRQHandler             [WEAK]
                EXPORT  EXTI2_3_IRQHandler             [WEAK]
                EXPORT  EXTI4_15_IRQHandler            [WEAK]
                EXPORT  TSC_IRQHandler                  [WEAK]
                EXPORT  DMA1_Channel1_IRQHandler       [WEAK]
                EXPORT  DMA1_Channel2_3_IRQHandler     [WEAK]
                EXPORT  DMA1_Channel4_5_IRQHandler     [WEAK]
                EXPORT  ADC1_IRQHandler                [WEAK]
                EXPORT  TIM1_BRK_UP_TRG_COM_IRQHandler [WEAK]
                EXPORT  TIM1_CC_IRQHandler             [WEAK]
                EXPORT  TIM2_IRQHandler                [WEAK]
                EXPORT  TIM3_IRQHandler                [WEAK]
                EXPORT  TIM14_IRQHandler               [WEAK]
                EXPORT  TIM16_IRQHandler               [WEAK]
                EXPORT  TIM17_IRQHandler               [WEAK]
                EXPORT  I2C1_IRQHandler                [WEAK]
                EXPORT  SPI1_IRQHandler                [WEAK]
                EXPORT  SPI2_IRQHandler                [WEAK]
                EXPORT  USART1_IRQHandler              [WEAK]
                EXPORT  USART2_IRQHandler              [WEAK]
                EXPORT  CEC_CAN_IRQHandler             [WEAK]
                EXPORT  USB_IRQHandler                 [WEAK]

WWDG_IRQHandler
PVD_VDDIO2_IRQHandler
RTC_IRQHandler
FLASH_IRQHandler
RCC_CRS_IRQHandler
EXTI0_1_IRQHandler
EXTI2_3_IRQHandler
EXTI4_15_IRQHandler
TSC_IRQHandler
DMA1_Channel1_IRQHandler
DMA1_Channel2_3_IRQHandler
DMA1_Channel4_5_IRQHandler
ADC1_IRQHandler
TIM1_BRK_UP_TRG_COM_IRQHandler
TIM1_CC_IRQHandler
TIM2_IRQHandler
TIM3_IRQHandler
TIM14_IRQHandler
TIM16_IRQHandler
TIM17_IRQHandler
I2C1_IRQHandler
SPI1_IRQHandler
SPI2_IRQHandler
USART1_IRQHandler
USART2_IRQHandler
CEC_CAN_IRQHandler
USB_IRQHandler   

                B       .

                ENDP

                ALIGN

;*******************************************************************************
; User Stack and Heap initialization
;*******************************************************************************
                 IF      :DEF:__MICROLIB

                 EXPORT  __initial_sp
                 EXPORT  __heap_base
                 EXPORT  __heap_limit

                 ELSE

                 IMPORT  __use_two_region_memory
                 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 STMicroelectronics *****END OF FILE*****

后记

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