STM32启动文件学习（startup_stm32f40xx.s）
原代码
;******************** (C) COPYRIGHT 2016 STMicroelectronics ********************
;* File Name : startup_stm32f40xx.s
;* Author : MCD Application Team
;* @version : V1.8.0
;* @date : 09-November-2016
;* Description : STM32F40xxx/41xxx devices vector table for MDK-ARM toolchain.
;* Same as startup_stm32f40_41xxx.s and maintained for legacy purpose
;* 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 and the external SRAM mounted on
;* STM324xG-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 CortexM4 processor is in Thread mode,
;* priority is Privileged, and the Stack is set to Main.
;* <<< Use Configuration Wizard in Context Menu >>>
;*******************************************************************************
;
; 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.
;
;*******************************************************************************
; Amount of memory (in bytes) allocated for Stack
; Tailor this value to your application needs
; Stack Configuration
; Stack Size (in Bytes) <0x0-0xFFFFFFFF:8>
;
Stack_Size EQU 0x00000400
AREA STACK, NOINIT, READWRITE, ALIGN=3
Stack_Mem SPACE Stack_Size
__initial_sp
; Heap Configuration
; Heap Size (in Bytes) <0x0-0xFFFFFFFF:8>
;
Heap_Size EQU 0x00000200
AREA HEAP, NOINIT, READWRITE, ALIGN=3
__heap_base
Heap_Mem SPACE Heap_Size
__heap_limit
PRESERVE8
THUMB
; Vector Table Mapped to Address 0 at Reset
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 detection
DCD TAMP_STAMP_IRQHandler ; Tamper and TimeStamps through the EXTI line
DCD RTC_WKUP_IRQHandler ; RTC Wakeup through the EXTI line
DCD FLASH_IRQHandler ; FLASH
DCD RCC_IRQHandler ; RCC
DCD EXTI0_IRQHandler ; EXTI Line0
DCD EXTI1_IRQHandler ; EXTI Line1
DCD EXTI2_IRQHandler ; EXTI Line2
DCD EXTI3_IRQHandler ; EXTI Line3
DCD EXTI4_IRQHandler ; EXTI Line4
DCD DMA1_Stream0_IRQHandler ; DMA1 Stream 0
DCD DMA1_Stream1_IRQHandler ; DMA1 Stream 1
DCD DMA1_Stream2_IRQHandler ; DMA1 Stream 2
DCD DMA1_Stream3_IRQHandler ; DMA1 Stream 3
DCD DMA1_Stream4_IRQHandler ; DMA1 Stream 4
DCD DMA1_Stream5_IRQHandler ; DMA1 Stream 5
DCD DMA1_Stream6_IRQHandler ; DMA1 Stream 6
DCD ADC_IRQHandler ; ADC1, ADC2 and ADC3s
DCD CAN1_TX_IRQHandler ; CAN1 TX
DCD CAN1_RX0_IRQHandler ; CAN1 RX0
DCD CAN1_RX1_IRQHandler ; CAN1 RX1
DCD CAN1_SCE_IRQHandler ; CAN1 SCE
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 TIM11
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 ; External Line[15:10]s
DCD RTC_Alarm_IRQHandler ; RTC Alarm (A and B) through EXTI Line
DCD OTG_FS_WKUP_IRQHandler ; USB OTG FS Wakeup through EXTI line
DCD TIM8_BRK_TIM12_IRQHandler ; TIM8 Break and TIM12
DCD TIM8_UP_TIM13_IRQHandler ; TIM8 Update and TIM13
DCD TIM8_TRG_COM_TIM14_IRQHandler ; TIM8 Trigger and Commutation and TIM14
DCD TIM8_CC_IRQHandler ; TIM8 Capture Compare
DCD DMA1_Stream7_IRQHandler ; DMA1 Stream7
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_DAC_IRQHandler ; TIM6 and DAC1&2 underrun errors
DCD TIM7_IRQHandler ; TIM7
DCD DMA2_Stream0_IRQHandler ; DMA2 Stream 0
DCD DMA2_Stream1_IRQHandler ; DMA2 Stream 1
DCD DMA2_Stream2_IRQHandler ; DMA2 Stream 2
DCD DMA2_Stream3_IRQHandler ; DMA2 Stream 3
DCD DMA2_Stream4_IRQHandler ; DMA2 Stream 4
DCD ETH_IRQHandler ; Ethernet
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
DCD OTG_FS_IRQHandler ; USB OTG FS
DCD DMA2_Stream5_IRQHandler ; DMA2 Stream 5
DCD DMA2_Stream6_IRQHandler ; DMA2 Stream 6
DCD DMA2_Stream7_IRQHandler ; DMA2 Stream 7
DCD USART6_IRQHandler ; USART6
DCD I2C3_EV_IRQHandler ; I2C3 event
DCD I2C3_ER_IRQHandler ; I2C3 error
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
DCD OTG_HS_WKUP_IRQHandler ; USB OTG HS Wakeup through EXTI
DCD OTG_HS_IRQHandler ; USB OTG HS
DCD DCMI_IRQHandler ; DCMI
DCD CRYP_IRQHandler ; CRYP crypto
DCD HASH_RNG_IRQHandler ; Hash and Rng
DCD FPU_IRQHandler ; FPU
__Vectors_End
__Vectors_Size EQU __Vectors_End - __Vectors
AREA |.text|, CODE, READONLY
; Reset handler
Reset_Handler PROC
EXPORT Reset_Handler [WEAK]
IMPORT SystemInit
IMPORT __main
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 .
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 TAMP_STAMP_IRQHandler [WEAK]
EXPORT RTC_WKUP_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_Stream0_IRQHandler [WEAK]
EXPORT DMA1_Stream1_IRQHandler [WEAK]
EXPORT DMA1_Stream2_IRQHandler [WEAK]
EXPORT DMA1_Stream3_IRQHandler [WEAK]
EXPORT DMA1_Stream4_IRQHandler [WEAK]
EXPORT DMA1_Stream5_IRQHandler [WEAK]
EXPORT DMA1_Stream6_IRQHandler [WEAK]
EXPORT ADC_IRQHandler [WEAK]
EXPORT CAN1_TX_IRQHandler [WEAK]
EXPORT CAN1_RX0_IRQHandler [WEAK]
EXPORT CAN1_RX1_IRQHandler [WEAK]
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]
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 RTC_Alarm_IRQHandler [WEAK]
EXPORT OTG_FS_WKUP_IRQHandler [WEAK]
EXPORT TIM8_BRK_TIM12_IRQHandler [WEAK]
EXPORT TIM8_UP_TIM13_IRQHandler [WEAK]
EXPORT TIM8_TRG_COM_TIM14_IRQHandler [WEAK]
EXPORT TIM8_CC_IRQHandler [WEAK]
EXPORT DMA1_Stream7_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_DAC_IRQHandler [WEAK]
EXPORT TIM7_IRQHandler [WEAK]
EXPORT DMA2_Stream0_IRQHandler [WEAK]
EXPORT DMA2_Stream1_IRQHandler [WEAK]
EXPORT DMA2_Stream2_IRQHandler [WEAK]
EXPORT DMA2_Stream3_IRQHandler [WEAK]
EXPORT DMA2_Stream4_IRQHandler [WEAK]
EXPORT ETH_IRQHandler [WEAK]
EXPORT ETH_WKUP_IRQHandler [WEAK]
EXPORT CAN2_TX_IRQHandler [WEAK]
EXPORT CAN2_RX0_IRQHandler [WEAK]
EXPORT CAN2_RX1_IRQHandler [WEAK]
EXPORT CAN2_SCE_IRQHandler [WEAK]
EXPORT OTG_FS_IRQHandler [WEAK]
EXPORT DMA2_Stream5_IRQHandler [WEAK]
EXPORT DMA2_Stream6_IRQHandler [WEAK]
EXPORT DMA2_Stream7_IRQHandler [WEAK]
EXPORT USART6_IRQHandler [WEAK]
EXPORT I2C3_EV_IRQHandler [WEAK]
EXPORT I2C3_ER_IRQHandler [WEAK]
EXPORT OTG_HS_EP1_OUT_IRQHandler [WEAK]
EXPORT OTG_HS_EP1_IN_IRQHandler [WEAK]
EXPORT OTG_HS_WKUP_IRQHandler [WEAK]
EXPORT OTG_HS_IRQHandler [WEAK]
EXPORT DCMI_IRQHandler [WEAK]
EXPORT CRYP_IRQHandler [WEAK]
EXPORT HASH_RNG_IRQHandler [WEAK]
EXPORT FPU_IRQHandler [WEAK]
WWDG_IRQHandler
PVD_IRQHandler
TAMP_STAMP_IRQHandler
RTC_WKUP_IRQHandler
FLASH_IRQHandler
RCC_IRQHandler
EXTI0_IRQHandler
EXTI1_IRQHandler
EXTI2_IRQHandler
EXTI3_IRQHandler
EXTI4_IRQHandler
DMA1_Stream0_IRQHandler
DMA1_Stream1_IRQHandler
DMA1_Stream2_IRQHandler
DMA1_Stream3_IRQHandler
DMA1_Stream4_IRQHandler
DMA1_Stream5_IRQHandler
DMA1_Stream6_IRQHandler
ADC_IRQHandler
CAN1_TX_IRQHandler
CAN1_RX0_IRQHandler
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
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
RTC_Alarm_IRQHandler
OTG_FS_WKUP_IRQHandler
TIM8_BRK_TIM12_IRQHandler
TIM8_UP_TIM13_IRQHandler
TIM8_TRG_COM_TIM14_IRQHandler
TIM8_CC_IRQHandler
DMA1_Stream7_IRQHandler
FSMC_IRQHandler
SDIO_IRQHandler
TIM5_IRQHandler
SPI3_IRQHandler
UART4_IRQHandler
UART5_IRQHandler
TIM6_DAC_IRQHandler
TIM7_IRQHandler
DMA2_Stream0_IRQHandler
DMA2_Stream1_IRQHandler
DMA2_Stream2_IRQHandler
DMA2_Stream3_IRQHandler
DMA2_Stream4_IRQHandler
ETH_IRQHandler
ETH_WKUP_IRQHandler
CAN2_TX_IRQHandler
CAN2_RX0_IRQHandler
CAN2_RX1_IRQHandler
CAN2_SCE_IRQHandler
OTG_FS_IRQHandler
DMA2_Stream5_IRQHandler
DMA2_Stream6_IRQHandler
DMA2_Stream7_IRQHandler
USART6_IRQHandler
I2C3_EV_IRQHandler
I2C3_ER_IRQHandler
OTG_HS_EP1_OUT_IRQHandler
OTG_HS_EP1_IN_IRQHandler
OTG_HS_WKUP_IRQHandler
OTG_HS_IRQHandler
DCMI_IRQHandler
CRYP_IRQHandler
HASH_RNG_IRQHandler
FPU_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*****
框架讲解
STM32F40xx 系列微控制器的标准启动代码（Startup Code）（汇编语言编写）用于芯片复位后的初始化和引导流程。
整体结构与功能
- 设置堆栈（Stack/Heap）：定义程序运行时的栈和堆空间。
- 向量表（Vector Table）：存储中断和异常处理函数的地址，复位后由硬件自动加载。
- 复位处理流程：初始化系统时钟，跳转到 C 语言的main函数。
- 默认中断处理函数：提供未实现中断的默认处理（死循环），用户可自定义替换。
详细代码解析
;******************** (C) COPYRIGHT 2016 STMicroelectronics ********************
; 文件名: startup_stm32f40xx.s
; 作者: MCD Application Team
; @version: V1.8.0
; @date: 09-November-2016
; 描述: STM32F40xxx/41xxx设备的向量表，用于MDK-ARM工具链。
; 与startup_stm32f40_41xxx.s相同，为遗留目的而维护。
; 本模块执行以下操作：
; - 设置初始堆栈指针（SP）
; - 设置初始程序计数器（PC）等于复位处理程序（Reset_Handler）
; - 在向量表条目中设置异常中断服务程序（ISR）的地址
; - 配置系统时钟和STM324xG-EVAL板上的外部SRAM，用作数据存储器（可选，用户启用）
; - 跳转到C库中的__main（最终调用main()）。
; 复位后，Cortex-M4处理器处于线程模式，优先级为特权级，堆栈设置为主堆栈。
; <<< 在上下文菜单中使用配置向导 >>>
;*******************************************************************************
; 许可证信息...
; 为堆栈分配的内存量（以字节为单位）
; 根据应用程序的需要调整此值
; <h> 堆栈配置
; <o> 堆栈大小（以字节为单位） <0x0-0xFFFFFFFF:8>
; </h>
Stack_Size EQU 0x00000400 ; 堆栈大小定义为1024字节
AREA STACK, NOINIT, READWRITE, ALIGN=3 ; 定义一个名为STACK的内存区域，未初始化，可读可写，8字节对齐
Stack_Mem SPACE Stack_Size ; 在STACK区域中分配Stack_Size大小的空间
__initial_sp ; 堆栈顶部指针的标记
; <h> 堆配置
; <o> 堆大小（以字节为单位） <0x0-0xFFFFFFFF:8>
; </h>
Heap_Size EQU 0x00000200 ; 堆大小定义为512字节
AREA HEAP, NOINIT, READWRITE, ALIGN=3 ; 定义一个名为HEAP的内存区域，未初始化，可读可写，8字节对齐
__heap_base ; 堆基地址的标记
Heap_Mem SPACE Heap_Size ; 在HEAP区域中分配Heap_Size大小的空间
__heap_limit ; 堆限制地址的标记
PRESERVE8 ; 确保堆栈8字节对齐
THUMB ; 指示接下来的代码以Thumb指令集执行
; 向量表映射到复位时的地址0
AREA RESET, DATA, READONLY ; 定义一个名为RESET的内存区域，数据段，只读
EXPORT __Vectors ; 导出向量表符号，使其可在其他文件中引用
EXPORT __Vectors_End ; 导出向量表结束符号
EXPORT __Vectors_Size ; 导出向量表大小符号
__Vectors DCD __initial_sp ; 向量表第一项：堆栈顶部地址
DCD Reset_Handler ; 向量表第二项：复位处理程序地址
DCD NMI_Handler ; 向量表第三项：NMI处理程序地址
; ...（其他异常和中断处理程序地址）
DCD FPU_IRQHandler ; 向量表最后一项：FPU中断处理程序地址
__Vectors_End ; 向量表结束标记
__Vectors_Size EQU __Vectors_End - __Vectors ; 计算向量表大小
AREA |.text|, CODE, READONLY ; 定义一个名为.text的内存区域，代码段，只读
; 复位处理程序
Reset_Handler PROC
EXPORT Reset_Handler [WEAK] ; 弱导出Reset_Handler，允许用户覆盖
IMPORT SystemInit ; 导入SystemInit函数
IMPORT __main ; 导入__main函数
LDR R0, =SystemInit ; 将SystemInit函数的地址加载到R0寄存器
BLX R0 ; 跳转到SystemInit函数执行
LDR R0, =__main ; 将__main函数的地址加载到R0寄存器
BX R0 ; 跳转到__main函数执行
ENDP ; 结束Reset_Handler过程
; 虚拟异常处理程序（无限循环，可以修改）
NMI_Handler PROC
EXPORT NMI_Handler [WEAK] ; 弱导出NMI_Handler，允许用户覆盖
B . ; 无限循环
ENDP ; 结束NMI_Handler过程
; ...（其他异常处理程序，结构类似NMI_Handler）
Default_Handler PROC
; 为所有未覆盖的外部中断处理程序提供默认实现
; ...（列出所有外部中断处理程序的弱导出）
B . ; 无限循环
ENDP ; 结束Default_Handler过程
ALIGN ; 确保接下来的代码按字对齐
; 用户堆栈和堆初始化（如果使用微库，则不需要此部分）
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 ; 加载堆基地址到R0
LDR R1, =(Stack_Mem + Stack_Size) ; 计算堆栈顶部地址并加载到R1
LDR R2, = (Heap_Mem + Heap_Size) ; 加载堆限制地址到R2
LDR R3, = Stack_Mem ; 加载堆栈基地址到R3
BX LR ; 返回
ALIGN ; 确保接下来的代码按字对齐
ENDIF
END ; 结束文件
;************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE*****
Q&A
1.AREA STACK, NOINIT, READWRITE, ALIGN=3什么意思
- AREA 指令：
这是 ARM 汇编语言中的一个伪指令，用于定义一个内存区域（Section）。
语法：AREA 区域名, 属性1, 属性2, … - STACK：
这是你给这个内存区域起的名字，可以自定义，但通常习惯用 “STACK” 表示栈区域。 - NOINIT：
这个属性表示该内存区域不需要初始化。
也就是说，系统不会在启动时为这个区域填充初始值（如 0），其内容是未定义的。
栈空间通常不需要预先初始化，因为程序运行时会动态使用它。 - READWRITE：
表示该区域具有读写权限。
栈需要能够被程序读写（压栈和出栈操作），所以设置为读写属性。 - ALIGN=3：
指定该区域的起始地址要按 2 的幂次方对齐。
ALIGN=3 表示按 2³ = 8 字节对齐。
这样可以确保栈的起始地址是 8 的倍数，提高内存访问效率。
2.Stack_Size和Heap_Size最大能分配到多少
Stack_Size（堆栈大小）和Heap_Size（堆大小）的总和不能超过SRAM的总大小，否则会导致内存溢出和程序崩溃
在设置这些值时，建议从较小的值开始，并逐步增加，直到找到满足应用程序需求的最佳平衡点。同时，还需要注意监控内存使用情况，以避免内存溢出和其他潜在问题。
3.malloc超出堆空间怎么办
在使用malloc的时候要去读取malloc函数带回来的返回值，正常malloc成功返回的是开辟好空间的指针，malloc失败就返回空指针，一定要检查。再对Heap做出调整