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本文详细介绍STM32单片机启动的过程,既从上电Reset_Handle跳转到main()函数的过程。其中,会着重解释__main的汇编代码
<>STM32启动过程
<>1. 从Reset_Handler开始启动
Reset_Handler的代码如下,参考《startup_stm32f10x_hd.s》
1-计算SystemInit函数入口地址,并把地址load到R0;
R0 = [PC + 24] = [0x08000144 + 24 +4] = [0x08000160] = 0x08000495
2 – 执行r0所指向的函数,既 SystemInit();同时,把下一条指令的地址(既PC+4)保存到lr(r14)中
3 – 计算__main的入口地址,并load到r0
4 – 执行__main()
<>__main 的执行过程
* __main函数内容
* SP(R13)赋值
SP = [pc +12 +4] = [0x08000130 + 12 + 4] = [0x08000140] = 0x20000408
* 执行 __scatterload() (地址0x08000168),并load R14, lr = 0x08000139
<>__scatterload函数执行过程
<>__scatterload_copy执行过程
<>__scatterload_zeroinit执行过程
<>__main_after_scatterload执行过程