//1 使能系统时钟

// 系统时钟初始化  - 不加入会报错 可以尝试一下
void SystemInit(void)
{
  //对地址 0xE000ED88 的内容 进行修改:
  //将0X3向左移动20位 或上 0X3 向左移动22位
  *(unsigned int*) 0xE000ED88|=((3UL << 20U)|(3UL << 22U));
}

int main() 
{
    //GPIOC的RCC寄存器地址，将位2置为1，使能GPIOC的RCC时钟
    *(unsigned int*)0x56020C8C |=1<<2;
    //PC13，配置为通用输出模式，位27和26置为01
    *(unsigned int*)0x52020800 &=~(1<<27);
    *(unsigned int*)0x52020800 |=1<<26;
//GPIO_OTYPER寄存器位13写入0
    *(unsigned int*) (0x52020800+0x04) &=~(1<<13);
//GPIO_OSPEEDR位27和位26写入00
    *(unsigned int*) (0x52020800+0x08) &=~(1<<27);
    *(unsigned int*) (0x52020800+0x08) &=~(1<<26);
//GPIO_ODR寄存器位13写入1 高电平
    *(unsigned int*) (0x52020800+0x14) |=(1<<13);
    
    //PC06,配置为通用输出模式.位13和位12置为01
    *(unsigned int*)0x52020800 &=~(1<<13);
    *(unsigned int*)0x52020800 |=1<<12;
    //GPIO_OTYPER寄存器位06写入0
    *(unsigned int*) (0x52020800+0x04) &=~(1<<6);
    //GPIO_OSPEEDR位13和位12写入00
    *(unsigned int*) (0x52020800+0x08) &=~(1<<13);
    *(unsigned int*) (0x52020800+0x08) &=~(1<<12);
    //GPIO_ODR寄存器位13写入1 高电平
    *(unsigned int*) (0x52020800+0x14) |=(1<<6);
    
    
    //GPIOC的RCC寄存器地址，将位2置为1，使能GPIOC的RCC时钟
    *(unsigned int*)0x56020C8C |=1;
    //PA15，配置为通用输出模式，位31和30置为01
    *(unsigned int*)0x52020000 &=~(1<<31);
    *(unsigned int*)0x52020000 |=1<<30;
    //GPIO_OTYPER寄存器位15写入0
    *(unsigned int*) (0x52020000+0x04) &=~(1<<15);
        //GPIO_OSPEEDR位31和位30写入00
    *(unsigned int*) (0x52020000+0x08) &=~(1<<31);
    *(unsigned int*) (0x52020000+0x08) &=~(1<<30);
    //GPIO_ODR寄存器位15写入1 高电平
    *(unsigned int*) (0x52020000+0x14) |=(1<<15);
    return 0;
}
//2 使能GPIO总线上的时钟
//3 配置GPIO相关的寄存器