/********************************** (C) COPYRIGHT *******************************
 * File Name          : system_ch32v20x.c
 * Author             : WCH
 * Version            : V1.0.0
 * Date               : 2021/06/06
 * Description        : CH32V20x Device Peripheral Access Layer System Source File.
 *                      For HSE = 32Mhz (CH32V208x/CH32V203RBT6)
 *                      For HSE = 8Mhz (other CH32V203x)
*********************************************************************************
* Copyright (c) 2021 Nanjing Qinheng Microelectronics Co., Ltd.
* Attention: This software (modified or not) and binary are used for 
* microcontroller manufactured by Nanjing Qinheng Microelectronics.
*******************************************************************************/
#include "ch32v20x.h" 

/* 
* Uncomment the line corresponding to the desired System clock (SYSCLK) frequency (after 
* reset the HSI is used as SYSCLK source).
* If none of the define below is enabled, the HSI is used as System clock source. 
*/
//#define SYSCLK_FREQ_HSE    HSE_VALUE
//#define SYSCLK_FREQ_48MHz_HSE  48000000
//#define SYSCLK_FREQ_56MHz_HSE  56000000
//#define SYSCLK_FREQ_72MHz_HSE  72000000
//#define SYSCLK_FREQ_96MHz_HSE  96000000
//#define SYSCLK_FREQ_120MHz_HSE  120000000
//#define SYSCLK_FREQ_144MHz_HSE  144000000
//#define SYSCLK_FREQ_HSI    HSI_VALUE
#define SYSCLK_FREQ_48MHz_HSI  48000000
//#define SYSCLK_FREQ_56MHz_HSI  56000000
//#define SYSCLK_FREQ_72MHz_HSI  72000000
//#define SYSCLK_FREQ_96MHz_HSI  96000000
//#define SYSCLK_FREQ_120MHz_HSI  120000000
//#define SYSCLK_FREQ_144MHz_HSI  144000000

/* Clock Definitions */
#ifdef SYSCLK_FREQ_HSE
uint32_t SystemCoreClock         = SYSCLK_FREQ_HSE;              /* System Clock Frequency (Core Clock) */
#elif defined SYSCLK_FREQ_48MHz_HSE
uint32_t SystemCoreClock         = SYSCLK_FREQ_48MHz_HSE;        /* System Clock Frequency (Core Clock) */
#elif defined SYSCLK_FREQ_56MHz_HSE
uint32_t SystemCoreClock         = SYSCLK_FREQ_56MHz_HSE;        /* System Clock Frequency (Core Clock) */
#elif defined SYSCLK_FREQ_72MHz_HSE
uint32_t SystemCoreClock         = SYSCLK_FREQ_72MHz_HSE;        /* System Clock Frequency (Core Clock) */
#elif defined SYSCLK_FREQ_96MHz_HSE
uint32_t SystemCoreClock         = SYSCLK_FREQ_96MHz_HSE;        /* System Clock Frequency (Core Clock) */
#elif defined SYSCLK_FREQ_120MHz_HSE
uint32_t SystemCoreClock         = SYSCLK_FREQ_120MHz_HSE;        /* System Clock Frequency (Core Clock) */
#elif defined SYSCLK_FREQ_144MHz_HSE
uint32_t SystemCoreClock         = SYSCLK_FREQ_144MHz_HSE;        /* System Clock Frequency (Core Clock) */
#elif defined SYSCLK_FREQ_48MHz_HSI
uint32_t SystemCoreClock         = SYSCLK_FREQ_48MHz_HSI;        /* System Clock Frequency (Core Clock) */
#elif defined SYSCLK_FREQ_56MHz_HSI
uint32_t SystemCoreClock         = SYSCLK_FREQ_56MHz_HSI;        /* System Clock Frequency (Core Clock) */
#elif defined SYSCLK_FREQ_72MHz_HSI
uint32_t SystemCoreClock         = SYSCLK_FREQ_72MHz_HSI;        /* System Clock Frequency (Core Clock) */
#elif defined SYSCLK_FREQ_96MHz_HSI
uint32_t SystemCoreClock         = SYSCLK_FREQ_96MHz_HSI;        /* System Clock Frequency (Core Clock) */
#elif defined SYSCLK_FREQ_120MHz_HSI
uint32_t SystemCoreClock         = SYSCLK_FREQ_120MHz_HSI;        /* System Clock Frequency (Core Clock) */
#elif defined SYSCLK_FREQ_144MHz_HSI
uint32_t SystemCoreClock         = SYSCLK_FREQ_144MHz_HSI;        /* System Clock Frequency (Core Clock) */
#else
uint32_t SystemCoreClock         = HSI_VALUE;                    /* System Clock Frequency (Core Clock) */

#endif

__I uint8_t AHBPrescTable[16] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 7, 8, 9};


/* system_private_function_proto_types */
static void SetSysClock(void);

#ifdef SYSCLK_FREQ_HSE
static void SetSysClockToHSE( void );
#elif defined SYSCLK_FREQ_48MHz_HSE
static void SetSysClockTo48_HSE( void );
#elif defined SYSCLK_FREQ_56MHz_HSE
static void SetSysClockTo56_HSE( void );
#elif defined SYSCLK_FREQ_72MHz_HSE
static void SetSysClockTo72_HSE( void );
#elif defined SYSCLK_FREQ_96MHz_HSE
static void SetSysClockTo96_HSE( void );
#elif defined SYSCLK_FREQ_120MHz_HSE
static void SetSysClockTo120_HSE( void );
#elif defined SYSCLK_FREQ_144MHz_HSE
static void SetSysClockTo144_HSE( void );
#elif defined SYSCLK_FREQ_48MHz_HSI
static void SetSysClockTo48_HSI( void );
#elif defined SYSCLK_FREQ_56MHz_HSI
static void SetSysClockTo56_HSI( void );
#elif defined SYSCLK_FREQ_72MHz_HSI
static void SetSysClockTo72_HSI( void );
#elif defined SYSCLK_FREQ_96MHz_HSI
static void SetSysClockTo96_HSI( void );
#elif defined SYSCLK_FREQ_120MHz_HSI
static void SetSysClockTo120_HSI( void );
#elif defined SYSCLK_FREQ_144MHz_HSI
static void SetSysClockTo144_HSI( void );

#endif

/*********************************************************************
 * @fn      SystemInit
 *
 * @brief   Setup the microcontroller system Initialize the Embedded Flash Interface,
 *        the PLL and update the SystemCoreClock variable.
 *
 * @return  none
 */
void SystemInit (void)
{
  RCC->CTLR |= (uint32_t)0x00000001;
  RCC->CFGR0 &= (uint32_t)0xF0FF0000;
  RCC->CTLR &= (uint32_t)0xFEF6FFFF;
  RCC->CTLR &= (uint32_t)0xFFFBFFFF;
  RCC->CFGR0 &= (uint32_t)0xFF00FFFF;
  RCC->INTR = 0x009F0000;    
  SetSysClock();
}


/*********************************************************************
 * @fn      SystemCoreClockUpdate
 *
 * @brief   Update SystemCoreClock variable according to Clock Register Values.
 *
 * @return  none
 */
void SystemCoreClockUpdate (void)
{
  uint32_t tmp = 0, pllmull = 0, pllsource = 0, Pll_6_5 = 0;

  tmp = RCC->CFGR0 & RCC_SWS;

  switch (tmp)
  {
    case 0x00:
      SystemCoreClock = HSI_VALUE;
      break;
    case 0x04:
      SystemCoreClock = HSE_VALUE;
      break;
    case 0x08:
      pllmull = RCC->CFGR0 & RCC_PLLMULL;
      pllsource = RCC->CFGR0 & RCC_PLLSRC;
      pllmull = ( pllmull >> 18) + 2;

      if(pllmull == 17) pllmull = 18;

      if (pllsource == 0x00)
      {
          if(EXTEN->EXTEN_CTR & EXTEN_PLL_HSI_PRE){
              SystemCoreClock = HSI_VALUE * pllmull;
          }
          else{
              SystemCoreClock = (HSI_VALUE >> 1) * pllmull;
          }
      }
      else
      {
#if defined (CH32V20x_D8W)
        if((RCC->CFGR0 & (3<<22)) == (3<<22))
        {
          SystemCoreClock = ((HSE_VALUE>>1)) * pllmull;
        }
        else
#endif
        if ((RCC->CFGR0 & RCC_PLLXTPRE) != (uint32_t)RESET)
        {
#if defined (CH32V20x_D8) || defined (CH32V20x_D8W)
          SystemCoreClock = ((HSE_VALUE>>2) >> 1) * pllmull;
#else
          SystemCoreClock = (HSE_VALUE >> 1) * pllmull;
#endif
        }
        else
        {
#if defined (CH32V20x_D8) || defined (CH32V20x_D8W)
            SystemCoreClock = (HSE_VALUE>>2) * pllmull;
#else
          SystemCoreClock = HSE_VALUE * pllmull;
#endif
        }
      }

      if(Pll_6_5 == 1) SystemCoreClock = (SystemCoreClock / 2);

      break;
    default:
      SystemCoreClock = HSI_VALUE;
      break;
  }

  tmp = AHBPrescTable[((RCC->CFGR0 & RCC_HPRE) >> 4)];
  SystemCoreClock >>= tmp;
}

/*********************************************************************
 * @fn      SetSysClock
 *
 * @brief   Configures the System clock frequency, HCLK, PCLK2 and PCLK1 prescalers.
 *
 * @return  none
 */
static void SetSysClock(void)
{
  //GPIO_IPD_Unused();
#ifdef SYSCLK_FREQ_HSE
    SetSysClockToHSE();
#elif defined SYSCLK_FREQ_48MHz_HSE
    SetSysClockTo48_HSE();
#elif defined SYSCLK_FREQ_56MHz_HSE
    SetSysClockTo56_HSE();
#elif defined SYSCLK_FREQ_72MHz_HSE
    SetSysClockTo72_HSE();
#elif defined SYSCLK_FREQ_96MHz_HSE
    SetSysClockTo96_HSE();
#elif defined SYSCLK_FREQ_120MHz_HSE
    SetSysClockTo120_HSE();
#elif defined SYSCLK_FREQ_144MHz_HSE
    SetSysClockTo144_HSE();
#elif defined SYSCLK_FREQ_48MHz_HSI
    SetSysClockTo48_HSI();
#elif defined SYSCLK_FREQ_56MHz_HSI
    SetSysClockTo56_HSI();
#elif defined SYSCLK_FREQ_72MHz_HSI
    SetSysClockTo72_HSI();
#elif defined SYSCLK_FREQ_96MHz_HSI
    SetSysClockTo96_HSI();
#elif defined SYSCLK_FREQ_120MHz_HSI
    SetSysClockTo120_HSI();
#elif defined SYSCLK_FREQ_144MHz_HSI
    SetSysClockTo144_HSI();

#endif
 
 /* If none of the define above is enabled, the HSI is used as System clock
  * source (default after reset) 
	*/ 
}


#ifdef SYSCLK_FREQ_HSE

/*********************************************************************
 * @fn      SetSysClockToHSE
 *
 * @brief   Sets HSE as System clock source and configure HCLK, PCLK2 and PCLK1 prescalers.
 *
 * @return  none
 */
static void SetSysClockToHSE(void)
{
  __IO uint32_t StartUpCounter = 0, HSEStatus = 0;
  
   
  RCC->CTLR |= ((uint32_t)RCC_HSEON);
 
  /* Wait till HSE is ready and if Time out is reached exit */
  do
  {
    HSEStatus = RCC->CTLR & RCC_HSERDY;
    StartUpCounter++;  
  } while((HSEStatus == 0) && (StartUpCounter != HSE_STARTUP_TIMEOUT));

  if ((RCC->CTLR & RCC_HSERDY) != RESET)
  {
    HSEStatus = (uint32_t)0x01;
  }
  else
  {
    HSEStatus = (uint32_t)0x00;
  }  

  if (HSEStatus == (uint32_t)0x01)
  {
    /* HCLK = SYSCLK */
    RCC->CFGR0 |= (uint32_t)RCC_HPRE_DIV1;      
    /* PCLK2 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE2_DIV1;
    /* PCLK1 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE1_DIV1;
    
    /* Select HSE as system clock source
     *  CH32V20x_D6 (HSE=8MHZ)
     *  CH32V20x_D8 (HSE=32MHZ)
     *  CH32V20x_D8W (HSE=32MHZ)
     */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_SW));
    RCC->CFGR0 |= (uint32_t)RCC_SW_HSE;    

    /* Wait till HSE is used as system clock source */
    while ((RCC->CFGR0 & (uint32_t)RCC_SWS) != (uint32_t)0x04)
    {
    }
  }
  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 
		 */
  }  
}

#elif defined SYSCLK_FREQ_48MHz_HSE

/*********************************************************************
 * @fn      SetSysClockTo48_HSE
 *
 * @brief   Sets System clock frequency to 48MHz and configure HCLK, PCLK2 and PCLK1 prescalers.
 *
 * @return  none
 */
static void SetSysClockTo48_HSE(void)
{
  __IO uint32_t StartUpCounter = 0, HSEStatus = 0;
     
   
  RCC->CTLR |= ((uint32_t)RCC_HSEON);
  /* Wait till HSE is ready and if Time out is reached exit */
  do
  {
    HSEStatus = RCC->CTLR & RCC_HSERDY;
    StartUpCounter++;  
  } while((HSEStatus == 0) && (StartUpCounter != HSE_STARTUP_TIMEOUT));

  if ((RCC->CTLR & RCC_HSERDY) != RESET)
  {
    HSEStatus = (uint32_t)0x01;
  }
  else
  {
    HSEStatus = (uint32_t)0x00;
  }  

  if (HSEStatus == (uint32_t)0x01)
  {
    /* HCLK = SYSCLK */
    RCC->CFGR0 |= (uint32_t)RCC_HPRE_DIV1;    
    /* PCLK2 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE2_DIV1;  
    /* PCLK1 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE1_DIV2;

    /*  CH32V20x_D6-PLL configuration: PLLCLK = HSE * 6 = 48 MHz (HSE=8MHZ)
     *  CH32V20x_D8-PLL configuration: PLLCLK = HSE/4 * 6 = 48 MHz (HSE=32MHZ)
     *  CH32V20x_D8W-PLL configuration: PLLCLK = HSE/4 * 6 = 48 MHz (HSE=32MHZ)
     */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_PLLSRC | RCC_PLLXTPRE | RCC_PLLMULL));

     RCC->CFGR0 |= (uint32_t)(RCC_PLLSRC_HSE | RCC_PLLXTPRE_HSE | RCC_PLLMULL6);

    /* Enable PLL */
    RCC->CTLR |= RCC_PLLON;
    /* Wait till PLL is ready */
    while((RCC->CTLR & RCC_PLLRDY) == 0)
    {
    }
    /* Select PLL as system clock source */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_SW));
    RCC->CFGR0 |= (uint32_t)RCC_SW_PLL;    
    /* Wait till PLL is used as system clock source */
    while ((RCC->CFGR0 & (uint32_t)RCC_SWS) != (uint32_t)0x08)
    {
    }
  }
  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 
		 */
  } 
}

#elif defined SYSCLK_FREQ_56MHz_HSE

/*********************************************************************
 * @fn      SetSysClockTo56_HSE
 *
 * @brief   Sets System clock frequency to 56MHz and configure HCLK, PCLK2 and PCLK1 prescalers.
 *
 * @return  none
 */
static void SetSysClockTo56_HSE(void)
{
  __IO uint32_t StartUpCounter = 0, HSEStatus = 0;
     
  RCC->CTLR |= ((uint32_t)RCC_HSEON);

  /* Wait till HSE is ready and if Time out is reached exit */
  do
  {
    HSEStatus = RCC->CTLR & RCC_HSERDY;
    StartUpCounter++;  
  } while((HSEStatus == 0) && (StartUpCounter != HSE_STARTUP_TIMEOUT));

  if ((RCC->CTLR & RCC_HSERDY) != RESET)
  {
    HSEStatus = (uint32_t)0x01;
  }
  else
  {
    HSEStatus = (uint32_t)0x00;
  }  

  if (HSEStatus == (uint32_t)0x01)
  {
    /* HCLK = SYSCLK */
    RCC->CFGR0 |= (uint32_t)RCC_HPRE_DIV1;   
    /* PCLK2 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE2_DIV1;
    /* PCLK1 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE1_DIV2;
  
    /*  CH32V20x_D6-PLL configuration: PLLCLK = HSE * 7 = 56 MHz (HSE=8MHZ)
     *  CH32V20x_D8-PLL configuration: PLLCLK = HSE/4 * 7 = 56 MHz (HSE=32MHZ)
     *  CH32V20x_D8W-PLL configuration: PLLCLK = HSE/4 * 7 = 56 MHz (HSE=32MHZ)
     */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_PLLSRC | RCC_PLLXTPRE | RCC_PLLMULL));

    RCC->CFGR0 |= (uint32_t)(RCC_PLLSRC_HSE | RCC_PLLXTPRE_HSE | RCC_PLLMULL7);

    /* Enable PLL */
    RCC->CTLR |= RCC_PLLON;
    /* Wait till PLL is ready */
    while((RCC->CTLR & RCC_PLLRDY) == 0)
    {
    }

    /* Select PLL as system clock source */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_SW));
    RCC->CFGR0 |= (uint32_t)RCC_SW_PLL;    
    /* Wait till PLL is used as system clock source */
    while ((RCC->CFGR0 & (uint32_t)RCC_SWS) != (uint32_t)0x08)
    {
    }
  }
  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 
		 */
  } 
}

#elif defined SYSCLK_FREQ_72MHz_HSE

/*********************************************************************
 * @fn      SetSysClockTo72_HSE
 *
 * @brief   Sets System clock frequency to 72MHz and configure HCLK, PCLK2 and PCLK1 prescalers.
 *
 * @return  none
 */
static void SetSysClockTo72_HSE(void)
{
  __IO uint32_t StartUpCounter = 0, HSEStatus = 0;
     
  RCC->CTLR |= ((uint32_t)RCC_HSEON);
 
  /* Wait till HSE is ready and if Time out is reached exit */
  do
  {
    HSEStatus = RCC->CTLR & RCC_HSERDY;
    StartUpCounter++;  
  } while((HSEStatus == 0) && (StartUpCounter != HSE_STARTUP_TIMEOUT));

  if ((RCC->CTLR & RCC_HSERDY) != RESET)
  {
    HSEStatus = (uint32_t)0x01;
  }
  else
  {
    HSEStatus = (uint32_t)0x00;
  }  

  if (HSEStatus == (uint32_t)0x01)
  {
    /* HCLK = SYSCLK */
    RCC->CFGR0 |= (uint32_t)RCC_HPRE_DIV1; 
    /* PCLK2 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE2_DIV1; 
    /* PCLK1 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE1_DIV2;
 
    /*  CH32V20x_D6-PLL configuration: PLLCLK = HSE * 9 = 72 MHz (HSE=8MHZ)
     *  CH32V20x_D8-PLL configuration: PLLCLK = HSE/4 * 9 = 72 MHz (HSE=32MHZ)
     *  CH32V20x_D8W-PLL configuration: PLLCLK = HSE/4 * 9 = 72 MHz (HSE=32MHZ)
     */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_PLLSRC | RCC_PLLXTPRE |
                                        RCC_PLLMULL));

    RCC->CFGR0 |= (uint32_t)(RCC_PLLSRC_HSE | RCC_PLLXTPRE_HSE | RCC_PLLMULL9);

    /* Enable PLL */
    RCC->CTLR |= RCC_PLLON;
    /* Wait till PLL is ready */
    while((RCC->CTLR & RCC_PLLRDY) == 0)
    {
    }    
    /* Select PLL as system clock source */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_SW));
    RCC->CFGR0 |= (uint32_t)RCC_SW_PLL;    
    /* Wait till PLL is used as system clock source */
    while ((RCC->CFGR0 & (uint32_t)RCC_SWS) != (uint32_t)0x08)
    {
    }
  }
  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 
		 */
  }
}


#elif defined SYSCLK_FREQ_96MHz_HSE

/*********************************************************************
 * @fn      SetSysClockTo96_HSE
 *
 * @brief   Sets System clock frequency to 96MHz and configure HCLK, PCLK2 and PCLK1 prescalers.
 *
 * @return  none
 */
static void SetSysClockTo96_HSE(void)
{
  __IO uint32_t StartUpCounter = 0, HSEStatus = 0;

  RCC->CTLR |= ((uint32_t)RCC_HSEON);

  /* Wait till HSE is ready and if Time out is reached exit */
  do
  {
    HSEStatus = RCC->CTLR & RCC_HSERDY;
    StartUpCounter++;
  } while((HSEStatus == 0) && (StartUpCounter != HSE_STARTUP_TIMEOUT));

  if ((RCC->CTLR & RCC_HSERDY) != RESET)
  {
    HSEStatus = (uint32_t)0x01;
  }
  else
  {
    HSEStatus = (uint32_t)0x00;
  }

  if (HSEStatus == (uint32_t)0x01)
  {
    /* HCLK = SYSCLK */
    RCC->CFGR0 |= (uint32_t)RCC_HPRE_DIV1;
    /* PCLK2 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE2_DIV1;
    /* PCLK1 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE1_DIV2;

    /*  CH32V20x_D6-PLL configuration: PLLCLK = HSE * 12 = 96 MHz (HSE=8MHZ)
     *  CH32V20x_D8-PLL configuration: PLLCLK = HSE/4 * 12 = 96 MHz (HSE=32MHZ)
     *  CH32V20x_D8W-PLL configuration: PLLCLK = HSE/4 * 12 = 96 MHz (HSE=32MHZ)
     */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_PLLSRC | RCC_PLLXTPRE |
                                        RCC_PLLMULL));

    RCC->CFGR0 |= (uint32_t)(RCC_PLLSRC_HSE | RCC_PLLXTPRE_HSE | RCC_PLLMULL12);

    /* Enable PLL */
    RCC->CTLR |= RCC_PLLON;
    /* Wait till PLL is ready */
    while((RCC->CTLR & RCC_PLLRDY) == 0)
    {
    }
    /* Select PLL as system clock source */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_SW));
    RCC->CFGR0 |= (uint32_t)RCC_SW_PLL;
    /* Wait till PLL is used as system clock source */
    while ((RCC->CFGR0 & (uint32_t)RCC_SWS) != (uint32_t)0x08)
    {
    }
  }
  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
         */
  }
}


#elif defined SYSCLK_FREQ_120MHz_HSE

/*********************************************************************
 * @fn      SetSysClockTo120_HSE
 *
 * @brief   Sets System clock frequency to 120MHz and configure HCLK, PCLK2 and PCLK1 prescalers.
 *
 * @return  none
 */
static void SetSysClockTo120_HSE(void)
{
    __IO uint32_t StartUpCounter = 0, HSEStatus = 0;

    RCC->CTLR |= ((uint32_t)RCC_HSEON);

    /* Wait till HSE is ready and if Time out is reached exit */
    do
    {
        HSEStatus = RCC->CTLR & RCC_HSERDY;
        StartUpCounter++;
    } while((HSEStatus == 0) && (StartUpCounter != HSE_STARTUP_TIMEOUT));

    if((RCC->CTLR & RCC_HSERDY) != RESET)
    {
        HSEStatus = (uint32_t)0x01;
    }
    else
    {
        HSEStatus = (uint32_t)0x00;
    }

    if(HSEStatus == (uint32_t)0x01)
    {
#if defined (CH32V20x_D8W)
        RCC->CFGR0 |= (uint32_t)(3<<22);
        /* HCLK = SYSCLK/2 */
        RCC->CFGR0 |= (uint32_t)RCC_HPRE_DIV2;
#else
        /* HCLK = SYSCLK */
        RCC->CFGR0 |= (uint32_t)RCC_HPRE_DIV1;
#endif
        /* PCLK2 = HCLK */
        RCC->CFGR0 |= (uint32_t)RCC_PPRE2_DIV1;
        /* PCLK1 = HCLK */
        RCC->CFGR0 |= (uint32_t)RCC_PPRE1_DIV2;

        /*  CH32V20x_D6-PLL configuration: PLLCLK = HSE * 15 = 120 MHz (HSE=8MHZ)
         *  CH32V20x_D8-PLL configuration: PLLCLK = HSE/4 * 15 = 120 MHz (HSE=32MHZ)
         *  CH32V20x_D8W-PLL configuration: PLLCLK = HSE/2 * 15 = 240 MHz (HSE=32MHZ)
         */
        RCC->CFGR0 &= (uint32_t)((uint32_t) ~(RCC_PLLSRC | RCC_PLLXTPRE |
                                              RCC_PLLMULL));

        RCC->CFGR0 |= (uint32_t)(RCC_PLLSRC_HSE | RCC_PLLXTPRE_HSE | RCC_PLLMULL15);

        /* Enable PLL */
        RCC->CTLR |= RCC_PLLON;
        /* Wait till PLL is ready */
        while((RCC->CTLR & RCC_PLLRDY) == 0)
        {
        }
        /* Select PLL as system clock source */
        RCC->CFGR0 &= (uint32_t)((uint32_t) ~(RCC_SW));
        RCC->CFGR0 |= (uint32_t)RCC_SW_PLL;
        /* Wait till PLL is used as system clock source */
        while((RCC->CFGR0 & (uint32_t)RCC_SWS) != (uint32_t)0x08)
        {
        }
    }
    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
         */
    }
}
#elif defined SYSCLK_FREQ_144MHz_HSE

/*********************************************************************
 * @fn      SetSysClockTo144_HSE
 *
 * @brief   Sets System clock frequency to 144MHz and configure HCLK, PCLK2 and PCLK1 prescalers.
 *
 * @return  none
 */
static void SetSysClockTo144_HSE(void)
{
  __IO uint32_t StartUpCounter = 0, HSEStatus = 0;

  RCC->CTLR |= ((uint32_t)RCC_HSEON);

  /* Wait till HSE is ready and if Time out is reached exit */
  do
  {
    HSEStatus = RCC->CTLR & RCC_HSERDY;
    StartUpCounter++;
  } while((HSEStatus == 0) && (StartUpCounter != HSE_STARTUP_TIMEOUT));

  if ((RCC->CTLR & RCC_HSERDY) != RESET)
  {
    HSEStatus = (uint32_t)0x01;
  }
  else
  {
    HSEStatus = (uint32_t)0x00;
  }

  if (HSEStatus == (uint32_t)0x01)
  {
    /* HCLK = SYSCLK */
    RCC->CFGR0 |= (uint32_t)RCC_HPRE_DIV1;
    /* PCLK2 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE2_DIV1;
    /* PCLK1 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE1_DIV2;

    /*  CH32V20x_D6-PLL configuration: PLLCLK = HSE * 18 = 144 MHz (HSE=8MHZ)
     *  CH32V20x_D8-PLL configuration: PLLCLK = HSE/4 * 18 = 144 MHz (HSE=32MHZ)
     *  CH32V20x_D8W-PLL configuration: PLLCLK = HSE/4 * 18 = 144 MHz (HSE=32MHZ)
     */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_PLLSRC | RCC_PLLXTPRE |
                                        RCC_PLLMULL));

    RCC->CFGR0 |= (uint32_t)(RCC_PLLSRC_HSE | RCC_PLLXTPRE_HSE | RCC_PLLMULL18);

    /* Enable PLL */
    RCC->CTLR |= RCC_PLLON;
    /* Wait till PLL is ready */
    while((RCC->CTLR & RCC_PLLRDY) == 0)
    {
    }
    /* Select PLL as system clock source */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_SW));
    RCC->CFGR0 |= (uint32_t)RCC_SW_PLL;
    /* Wait till PLL is used as system clock source */
    while ((RCC->CFGR0 & (uint32_t)RCC_SWS) != (uint32_t)0x08)
    {
    }
  }
  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
         */
  }
}

#elif defined SYSCLK_FREQ_48MHz_HSI

/*********************************************************************
 * @fn      SetSysClockTo48_HSI
 *
 * @brief   Sets System clock frequency to 48MHz and configure HCLK, PCLK2 and PCLK1 prescalers.
 *
 * @return  none
 */
static void SetSysClockTo48_HSI(void)
{
    EXTEN->EXTEN_CTR |= EXTEN_PLL_HSI_PRE;

    /* HCLK = SYSCLK */
    RCC->CFGR0 |= (uint32_t)RCC_HPRE_DIV1;
    /* PCLK2 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE2_DIV1;
    /* PCLK1 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE1_DIV2;

    /*  PLL configuration: PLLCLK = HSI * 6 = 48 MHz */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_PLLSRC | RCC_PLLXTPRE | RCC_PLLMULL));

     RCC->CFGR0 |= (uint32_t)(RCC_PLLSRC_HSI_Div2 | RCC_PLLMULL6);

    /* Enable PLL */
    RCC->CTLR |= RCC_PLLON;
    /* Wait till PLL is ready */
    while((RCC->CTLR & RCC_PLLRDY) == 0)
    {
    }
    /* Select PLL as system clock source */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_SW));
    RCC->CFGR0 |= (uint32_t)RCC_SW_PLL;
    /* Wait till PLL is used as system clock source */
    while ((RCC->CFGR0 & (uint32_t)RCC_SWS) != (uint32_t)0x08)
    {
    }
}

#elif defined SYSCLK_FREQ_56MHz_HSI

/*********************************************************************
 * @fn      SetSysClockTo56_HSI
 *
 * @brief   Sets System clock frequency to 56MHz and configure HCLK, PCLK2 and PCLK1 prescalers.
 *
 * @return  none
 */
static void SetSysClockTo56_HSI(void)
{
    EXTEN->EXTEN_CTR |= EXTEN_PLL_HSI_PRE;

    /* HCLK = SYSCLK */
    RCC->CFGR0 |= (uint32_t)RCC_HPRE_DIV1;
    /* PCLK2 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE2_DIV1;
    /* PCLK1 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE1_DIV2;

    /*  PLL configuration: PLLCLK = HSI * 7 = 48 MHz */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_PLLSRC | RCC_PLLXTPRE | RCC_PLLMULL));

     RCC->CFGR0 |= (uint32_t)(RCC_PLLSRC_HSI_Div2 | RCC_PLLMULL7);

    /* Enable PLL */
    RCC->CTLR |= RCC_PLLON;
    /* Wait till PLL is ready */
    while((RCC->CTLR & RCC_PLLRDY) == 0)
    {
    }
    /* Select PLL as system clock source */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_SW));
    RCC->CFGR0 |= (uint32_t)RCC_SW_PLL;
    /* Wait till PLL is used as system clock source */
    while ((RCC->CFGR0 & (uint32_t)RCC_SWS) != (uint32_t)0x08)
    {
    }
}

#elif defined SYSCLK_FREQ_72MHz_HSI

/*********************************************************************
 * @fn      SetSysClockTo72_HSI
 *
 * @brief   Sets System clock frequency to 72MHz and configure HCLK, PCLK2 and PCLK1 prescalers.
 *
 * @return  none
 */
static void SetSysClockTo72_HSI(void)
{
    EXTEN->EXTEN_CTR |= EXTEN_PLL_HSI_PRE;

    /* HCLK = SYSCLK */
    RCC->CFGR0 |= (uint32_t)RCC_HPRE_DIV1;
    /* PCLK2 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE2_DIV1;
    /* PCLK1 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE1_DIV2;

    /*  PLL configuration: PLLCLK = HSI * 9 = 72 MHz */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_PLLSRC | RCC_PLLXTPRE | RCC_PLLMULL));

     RCC->CFGR0 |= (uint32_t)(RCC_PLLSRC_HSI_Div2 | RCC_PLLMULL9);

    /* Enable PLL */
    RCC->CTLR |= RCC_PLLON;
    /* Wait till PLL is ready */
    while((RCC->CTLR & RCC_PLLRDY) == 0)
    {
    }
    /* Select PLL as system clock source */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_SW));
    RCC->CFGR0 |= (uint32_t)RCC_SW_PLL;
    /* Wait till PLL is used as system clock source */
    while ((RCC->CFGR0 & (uint32_t)RCC_SWS) != (uint32_t)0x08)
    {
    }
}


#elif defined SYSCLK_FREQ_96MHz_HSI

/*********************************************************************
 * @fn      SetSysClockTo96_HSI
 *
 * @brief   Sets System clock frequency to 96MHz and configure HCLK, PCLK2 and PCLK1 prescalers.
 *
 * @return  none
 */
static void SetSysClockTo96_HSI(void)
{
    EXTEN->EXTEN_CTR |= EXTEN_PLL_HSI_PRE;

    /* HCLK = SYSCLK */
    RCC->CFGR0 |= (uint32_t)RCC_HPRE_DIV1;
    /* PCLK2 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE2_DIV1;
    /* PCLK1 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE1_DIV2;

    /*  PLL configuration: PLLCLK = HSI * 12 = 96 MHz */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_PLLSRC | RCC_PLLXTPRE | RCC_PLLMULL));

     RCC->CFGR0 |= (uint32_t)(RCC_PLLSRC_HSI_Div2 | RCC_PLLMULL12);

    /* Enable PLL */
    RCC->CTLR |= RCC_PLLON;
    /* Wait till PLL is ready */
    while((RCC->CTLR & RCC_PLLRDY) == 0)
    {
    }
    /* Select PLL as system clock source */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_SW));
    RCC->CFGR0 |= (uint32_t)RCC_SW_PLL;
    /* Wait till PLL is used as system clock source */
    while ((RCC->CFGR0 & (uint32_t)RCC_SWS) != (uint32_t)0x08)
    {
    }
}


#elif defined SYSCLK_FREQ_120MHz_HSI

/*********************************************************************
 * @fn      SetSysClockTo120_HSI
 *
 * @brief   Sets System clock frequency to 120MHz and configure HCLK, PCLK2 and PCLK1 prescalers.
 *
 * @return  none
 */
static void SetSysClockTo120_HSI(void)
{
    EXTEN->EXTEN_CTR |= EXTEN_PLL_HSI_PRE;

    /* HCLK = SYSCLK */
    RCC->CFGR0 |= (uint32_t)RCC_HPRE_DIV1;
    /* PCLK2 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE2_DIV1;
    /* PCLK1 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE1_DIV2;

    /*  PLL configuration: PLLCLK = HSI * 15 = 120 MHz */
    RCC->CFGR0 &= (uint32_t)((uint32_t) ~(RCC_PLLSRC | RCC_PLLXTPRE |
                                          RCC_PLLMULL));

    RCC->CFGR0 |= (uint32_t)(RCC_PLLSRC_HSI_Div2 | RCC_PLLMULL15);

    /* Enable PLL */
    RCC->CTLR |= RCC_PLLON;
    /* Wait till PLL is ready */
    while((RCC->CTLR & RCC_PLLRDY) == 0)
    {
    }
    /* Select PLL as system clock source */
    RCC->CFGR0 &= (uint32_t)((uint32_t) ~(RCC_SW));
    RCC->CFGR0 |= (uint32_t)RCC_SW_PLL;
    /* Wait till PLL is used as system clock source */
    while((RCC->CFGR0 & (uint32_t)RCC_SWS) != (uint32_t)0x08)
    {
    }
}
#elif defined SYSCLK_FREQ_144MHz_HSI

/*********************************************************************
 * @fn      SetSysClockTo144_HSI
 *
 * @brief   Sets System clock frequency to 144MHz and configure HCLK, PCLK2 and PCLK1 prescalers.
 *
 * @return  none
 */
static void SetSysClockTo144_HSI(void)
{
    EXTEN->EXTEN_CTR |= EXTEN_PLL_HSI_PRE;

    /* HCLK = SYSCLK */
    RCC->CFGR0 |= (uint32_t)RCC_HPRE_DIV1;
    /* PCLK2 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE2_DIV1;
    /* PCLK1 = HCLK */
    RCC->CFGR0 |= (uint32_t)RCC_PPRE1_DIV2;

    /*  PLL configuration: PLLCLK = HSI * 18 = 144 MHz */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_PLLSRC | RCC_PLLXTPRE | RCC_PLLMULL));

     RCC->CFGR0 |= (uint32_t)(RCC_PLLSRC_HSI_Div2 | RCC_PLLMULL18);

    /* Enable PLL */
    RCC->CTLR |= RCC_PLLON;
    /* Wait till PLL is ready */
    while((RCC->CTLR & RCC_PLLRDY) == 0)
    {
    }
    /* Select PLL as system clock source */
    RCC->CFGR0 &= (uint32_t)((uint32_t)~(RCC_SW));
    RCC->CFGR0 |= (uint32_t)RCC_SW_PLL;
    /* Wait till PLL is used as system clock source */
    while ((RCC->CFGR0 & (uint32_t)RCC_SWS) != (uint32_t)0x08)
    {
    }
}


#endif