Archive

Posts Tagged ‘RCC’

STM32 – Overclocking

Have you ever wondered if it was possible to overclock the STM32? It is, with a simple change in code line!
We only have to change the PLL setting, which is able to go up to 16 – so that means that we can overclock the STM32 up to 8MHz x 16 = 128 MHz
Here is the RCC Initialization code for 128MHz – remember, you also have to comment the “SYSCLK_FREQ_72MHz”, uncomment the “SYSCLK_FREQ_HSE” and set it to 128MHz in the system_stm32f10x.c

/*******************************************************************************
* Function Name  : RCC_Configuration
* Description    : Configures the different system clocks.
* Input          : None
* Output         : None
* Return         : None
*******************************************************************************/
void RCC_Configuration(void)
   {
   /* RCC system reset(for debug purpose) */
   RCC_DeInit();

   /* Enable HSE */
   RCC_HSEConfig(RCC_HSE_ON);

   /* Wait till HSE is ready */
   HSEStartUpStatus = RCC_WaitForHSEStartUp();

   if(HSEStartUpStatus == SUCCESS)
      {
      /* Enable Prefetch Buffer */
      FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);

      /* Flash 2 wait state */
      FLASH_SetLatency(FLASH_Latency_2);

      /* HCLK = SYSCLK */
      RCC_HCLKConfig(RCC_SYSCLK_Div1); 

      /* PCLK2 = HCLK */
      RCC_PCLK2Config(RCC_HCLK_Div1); 

      /* PCLK1 = HCLK/2 */
      RCC_PCLK1Config(RCC_HCLK_Div2);

      /* PLLCLK = 8MHz * 9 = 72 MHz */
      //RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);  
      /* PLLCLK = 8MHz * 16 = 128 MHz */
      RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_16); 
      // The frequency has also been changed in system_stm32f10x

      /* Enable PLL */ 
      RCC_PLLCmd(ENABLE);

      /* Wait till PLL is ready */
      while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET)
         {;}

      /* Select PLL as system clock source */
      RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);

      /* Wait till PLL is used as system clock source */
      while(RCC_GetSYSCLKSource() != 0x08)
         {;}
      }

   /* Enable peripheral clocks --------------------------------------------------*/
   /* Enable GPIOA, GPIOB, GPIOC, GPIOD, GPIOE, GPIOF, GPIOG and AFIO clocks */
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB |RCC_APB2Periph_GPIOC 
         | RCC_APB2Periph_GPIOD | RCC_APB2Periph_GPIOE | RCC_APB2Periph_GPIOF | RCC_APB2Periph_GPIOG 
         | RCC_APB2Periph_AFIO, ENABLE);
   }
Categories: ARM Tags: , ,