HK32F030C8T6把OSC_IN和OSC_OUT作为普通的IO口使用

1.将OSC_IN和OSC_OUT初始化相应的模式

    GPIO_InitStructure.GPIO_Pin = CSB_GPIO_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_Init(CSB_GPIO_PORT, &GPIO_InitStructure);

	GPIO_InitStructure.GPIO_Pin = RSTB_GPIO_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;	
	GPIO_Init(RSTB_GPIO_PORT, &GPIO_InitStructure);

2.这样配置完之后发现GPIO输出的高电平电压完全达不到3.3V。原因是我们在初始化systemclock时，把外部晶振也初始化了。所以我们只需要把外部晶振不使能，就可以把OSC_IN和OSC_OUT当作普通的IO口使用了。

1. 打开函数 SystemInit();
2. 就会看到

   void SystemInit (void)
   {    
     /* Set HSION bit */
     RCC->CR |= (uint32_t)0x00000001;
   
     /* Reset SW[1:0], HPRE[3:0], PPRE[2:0], ADCPRE and MCOSEL[2:0] bits */
     RCC->CFGR &= (uint32_t)0xF8FFB80C;
     
     /* Reset HSEON, CSSON and PLLON bits */
     RCC->CR &= (uint32_t)0xFEF6FFFF;
   
     /* Reset HSEBYP bit */
     RCC->CR &= (uint32_t)0xFFFBFFFF;
   
     /* Reset PLLSRC, PLLXTPRE and PLLMUL[3:0] bits */
     RCC->CFGR &= (uint32_t)0xFFC0FFFF;
   
     /* Reset PREDIV1[3:0] bits */
     RCC->CFGR2 &= (uint32_t)0xFFFFFFF0;
   
     /* Reset USARTSW[1:0], I2CSW, CECSW and ADCSW bits */
     RCC->CFGR3 &= (uint32_t)0xFFFFFEAC;
   
     /* Reset HSI14 bit */
     RCC->CR2 &= (uint32_t)0xFFFFFFFE;
   
     /* Disable all interrupts */
     RCC->CIR = 0x00000000;
   
     /* Configure the System clock frequency, AHB/APBx prescalers and Flash settings */
     SetSysClock();
   }

3. 打开SetSysClock();并把 RCC->CR |= ((uint32_t)RCC_CR_HSEON) 修改为RCC->CR &= ~((uint32_t)RCC_CR_HSEON);

   static void SetSysClock(void)
   {
     __IO uint32_t StartUpCounter = 0, HSEStatus = 0;
   
   /******************************************************************************/
   /*            PLL (clocked by HSE) used as System clock source                */
   /******************************************************************************/
     
     /* SYSCLK, HCLK, PCLK configuration ----------------------------------------*/
     /* Enable HSE */    
     //RCC->CR |= ((uint32_t)RCC_CR_HSEON);
     RCC->CR &= ~((uint32_t)RCC_CR_HSEON);
     /* Wait till HSE is ready and if Time out is reached exit */
     do
     {
       HSEStatus = RCC->CR & RCC_CR_HSERDY;
       StartUpCounter++;  
     } while((HSEStatus == 0) && (StartUpCounter != HSE_STARTUP_TIMEOUT));
   
     if ((RCC->CR & RCC_CR_HSERDY) != RESET)
     {
       HSEStatus = (uint32_t)0x01;
     }
     else
     {
       HSEStatus = (uint32_t)0x00;
     }  
   
     if (HSEStatus == (uint32_t)0x01)
     {
       /* Enable Prefetch Buffer and set Flash Latency */
       FLASH->ACR = FLASH_ACR_PRFTBE | FLASH_ACR_LATENCY;
    
       /* HCLK = SYSCLK */
       RCC->CFGR |= (uint32_t)RCC_CFGR_HPRE_DIV1;
         
       /* PCLK = HCLK */
       RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE_DIV1;
   
       /* PLL configuration */
       RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_PLLSRC | RCC_CFGR_PLLXTPRE | RCC_CFGR_PLLMULL));
       RCC->CFGR |= (uint32_t)(RCC_CFGR_PLLSRC_PREDIV1 | RCC_CFGR_PLLXTPRE_PREDIV1 | RCC_CFGR_PLLMULL6);
               
       /* Enable PLL */
       RCC->CR |= RCC_CR_PLLON;
   
       /* Wait till PLL is ready */
       while((RCC->CR & RCC_CR_PLLRDY) == 0)
       {
       }
   
       /* Select PLL as system clock source */
       RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_SW));
       RCC->CFGR |= (uint32_t)RCC_CFGR_SW_PLL;    
   
       /* Wait till PLL is used as system clock source */
       while ((RCC->CFGR & (uint32_t)RCC_CFGR_SWS) != (uint32_t)RCC_CFGR_SWS_PLL)
       {
       }
     }
     else
     { /* If HSE fails to start-up, the application will have wrong clock 
            configuration. User can add here some code to deal with this error */
     }  
   }

4.完成这样的步骤就可以把OSC_IN和OSC_OUT当作IO口使用了。