位操作：打开位，关闭位，移位运算符

移位运算符

左移

右移

掩码

打开位

掩码按照需要设置的位设置

关闭位

检查位的值

点击查看代码

  /*CONFIGURE PA8为Alternate Function*/
#define  GPIOBBASE  0X40010C00ul
#define  GPIOABASE  0x40010800UL
#define  RCCBASE  0X40021000ul
  
 /*HSION, open bit 0*/
 *(volatile uint32_t*)(RCCBASE + 0X0) |=(0x1ul) << 0u; 
  while((*(volatile uint32_t*)RCCBASE) & 0x1ul != 0x1ul );
  
  /*配置PA8,CNF8，alternate pp模式, close bit [3.2]*/
  *(volatile uint32_t*)(GPIOABASE + 0X00) |= (~0x2ul) << 2u; 
  /*配置PB3,MODE3，50Mhz*/
  *(volatile uint32_t*)(GPIOABASE + 0X00) |= (0x3ul) << 0u; 
  
 *(volatile uint32_t*)(RCCBASE + 0X18)   |= (0x1UL);/*RCC_APB2ENR, AFIO开启*/
 //*(volatile uint32_t*)(RCCBASE + 0X04) |=(0x101ul) << 24u; /*选择那个时钟输出*/
 *(volatile uint32_t*)(RCCBASE + 0X04) |=(0x5ul) << 24u; /*选择那个时钟输出*/