#include "main.h"

#include "stm32l100c_discovery.h"

#include "ssd1306.h"

#include "config.h"

#include "eeprom_min.h"

// USB includes

#include "hw_config.h"

#include "usb_lib.h"

#include "usb_desc.h"

#include "usb_pwr.h"

#include "stringhelpers.h"

// TODO: Grab buttonpresses with interrupts

// USB Supporting Vars

extern __IO uint8_t Receive_Buffer[64];

extern __IO  uint32_t Receive_length ;

extern __IO  uint32_t length ;

uint8_t Send_Buffer[64];

uint32_t packet_sent=1;

uint32_t packet_receive=1;

// Globalish setting vars

uint8_t boottobrew = 0;

#define WINDUP_GUARD_GAIN 100

uint16_t windup_guard = WINDUP_GUARD_GAIN;

uint16_t k_p = 1;

uint16_t k_i = 1;

uint16_t k_d = 1;

// ISR ticks var TODO: Double check functionality after volatilazation... needed on ARM?

volatile uint32_t ticks = 0;

// Increase on each press, and increase at a fast rate after duration elapsed of continuously holding down... somehow...

uint32_t change_time_reset = 0;

#define CHANGE_PERIOD_MS 100

#define CHANGE_ELAPSED (ticks - change_time_reset) > CHANGE_PERIOD_MS

#define CHANGE_RESET change_time_reset = ticks

int16_t setpoint_brew = 0;

int16_t setpoint_steam = 0;

// State definition

enum state {

    STATE_IDLE = 0,

    STATE_SETP,

    STATE_SETI,

    STATE_SETD,

    STATE_SETWINDUP,

    STATE_SETBOOTTOBREW,

    STATE_PREHEAT_BREW,

    STATE_MAINTAIN_BREW,

    STATE_PREHEAT_STEAM,

    STATE_MAINTAIN_STEAM,

};

uint8_t state = STATE_IDLE;

static __IO uint32_t TimingDelay;

// Move to header file

void init_gpio();

void init_spi();

void process();

void machine();

void delay(__IO uint32_t nTime);

void restore_settings();

void save_settings();

void save_setpoints();

int main(void)

{

    // Init clocks

    SystemInit();

    // Init GPIO

    init_gpio();

    // Init USB

    //Set_USBClock();

    //USB_Interrupts_Config();

    //USB_Init();

    // Turn on power LED

    GPIO_SetBits(LED_POWER);

    // TODO: Awesome pwm of power LED (TIM4_CH4 or TIM11_CH1)

    // Configure 1ms SysTick (change if more temporal resolution needed) 

    RCC_ClocksTypeDef RCC_Clocks;

    RCC_GetClocksFreq(&RCC_Clocks);

    SysTick_Config(RCC_Clocks.HCLK_Frequency / 1000);

    // Init SPI busses

    init_spi();

    // Init OLED over SPI

    ssd1306_Init();

    ssd1306_clearscreen();

    // Startup screen 

    ssd1306_DrawString("therm v0.1", 1, 40);

    ssd1306_DrawString("protofusion.org/therm", 3, 0);

    delay(1500);

    ssd1306_clearscreen();

    restore_settings();

    if(boottobrew)

      state = STATE_PREHEAT_BREW; // Go to brew instead of idle if configured thusly

    GPIO_ResetBits(LED_STAT);

    // Main loop

    while(1)

    {

        // Process sensor inputs

        process();

        // Run state machine

        machine(); 

    }

}

// Read temperature and update global temp vars

int16_t temp = 0;

uint8_t temp_frac = 0;

void update_temp() {

    // Assert CS

    GPIO_ResetBits(MAX_CS);

    delay(1);

    // This may not clock at all... might need to send 16 bits first

    SPI_I2S_SendData(SPI2, 0xAAAA); // send dummy data

    //SPI_I2S_SendData(SPI2, 0xAA); // send dummy data

    uint16_t temp_pre = SPI_I2S_ReceiveData(SPI2);

    if(temp_pre & 0b0000000000000010) {

        ssd1306_DrawString("Fatal Error", 2, 35);

    }

    else if(temp_pre & 0b0000000000000001) {

        ssd1306_DrawString("Error: No TC", 2, 40);

        temp = 0;

        temp_frac = 0;

    }

    else 

    {

        uint8_t sign = temp >> 15;// top bit is sign

        temp_pre = temp_pre >> 2; // Drop 2 lowest bits

        temp_frac = temp_pre & 0b11; // get fractional part

        temp_frac *= 25; // each bit is .25 a degree, up to fixed point

        temp_pre = temp_pre >> 2; // Drop 2 fractional bits 

        if(sign) {

            temp = -temp_pre;

        }

        else {

            temp = temp_pre;

        }

    }

    // Deassert CS

    delay(1);

    GPIO_SetBits(MAX_CS);

}

// PID implementation

int16_t last_pid_temp = 0;

uint8_t last_pid_temp_frac = 0;

int16_t i_state = 0;

int16_t update_pid(uint16_t k_p, uint16_t k_i, uint16_t k_d, int16_t temp, uint8_t temp_frac, int16_t setpoint) 

{

  // Calculate instantaneous error

  int16_t error = (int16_t)setpoint - (int16_t)temp; // TODO: Use fixed point fraction

  // Proportional component

  int16_t p_term = k_p * error;

  // Error accumulator (integrator)

  i_state += error;

  // to prevent the iTerm getting huge despite lots of 

  //  error, we use a "windup guard" 

  // (this happens when the machine is first turned on and

  // it cant help be cold despite its best efforts)

  // not necessary, but this makes windup guard values 

  // relative to the current iGain

  int16_t windup_guard_res = WINDUP_GUARD_GAIN / k_i;  

  // Calculate integral term with windup guard 

  if (i_state > windup_guard_res) 

    i_state = windup_guard_res;

  else if (i_state < -windup_guard_res) 

    i_state = -windup_guard_res;

  int16_t i_term = k_i * i_state;

    // Kill SSR after elapsed period less than SSR_PERIOD 

    if(ticks - last_ssr_on > ssr_output || ssr_output == 0)

    {

        GPIO_ResetBits(LED_STAT);

        GPIO_ResetBits(SSR_PIN);

    }

}

void draw_setpoint() {

    char tempstr[3];

    itoa_fp(temp, temp_frac, tempstr);

    //ssd1306_DrawString("        ", 3, 40);

    ssd1306_DrawString(tempstr, 3, 40);

    ssd1306_DrawString("-> ", 3, 80);

    itoa(setpoint, tempstr);

    ssd1306_DrawString("    ", 3, 95);

    ssd1306_DrawString(tempstr, 3, 95);

}

uint8_t goto_mode = 2;

// State machine

uint8_t sw_btn_last = 0;

uint8_t sw_up_last = 0;

uint8_t sw_down_last = 0;

uint8_t sw_left_last = 0;

uint8_t sw_right_last = 0;

#define SW_BTN_PRESSED (sw_btn_last == 0 && sw_btn == 1) // rising edge on buttonpress

#define SW_UP_PRESSED (sw_up_last == 0 && sw_up == 1)

#define SW_DOWN_PRESSED (sw_down_last == 0 && sw_down == 1)

#define SW_LEFT_PRESSED (sw_left_last == 0 && sw_left == 1)

#define SW_RIGHT_PRESSED (sw_right_last == 0 && sw_right == 1)

#define EEPROM_ADDR_WINDUP_GUARD 	0x001C

#define EEPROM_ADDR_BOOTTOBREW		0x0020

#define EEPROM_ADDR_K_P			0x0024

#define EEPROM_ADDR_K_I			0x0028

#define EEPROM_ADDR_K_D			0x002C

#define EEPROM_ADDR_BREWTEMP		0x0030

#define EEPROM_ADDR_STEAMTEMP		0x0034

void save_settings()

{

   Minimal_EEPROM_Unlock();

    // Try programming a word at an address divisible by 4

    Minimal_EEPROM_ProgramWord(EEPROM_BASE_ADDR + EEPROM_ADDR_BOOTTOBREW, boottobrew);

    Minimal_EEPROM_ProgramWord(EEPROM_BASE_ADDR + EEPROM_ADDR_WINDUP_GUARD, windup_guard);

    Minimal_EEPROM_ProgramWord(EEPROM_BASE_ADDR + EEPROM_ADDR_K_P, k_p);

    Minimal_EEPROM_ProgramWord(EEPROM_BASE_ADDR + EEPROM_ADDR_K_I, k_i);

    Minimal_EEPROM_ProgramWord(EEPROM_BASE_ADDR + EEPROM_ADDR_K_D, k_d);

    Minimal_EEPROM_Lock();

}

void save_setpoints()

{

    Minimal_EEPROM_Unlock();

    Minimal_EEPROM_ProgramWord(EEPROM_BASE_ADDR + EEPROM_ADDR_BREWTEMP, setpoint_brew);

    Minimal_EEPROM_ProgramWord(EEPROM_BASE_ADDR + EEPROM_ADDR_STEAMTEMP, setpoint_steam); 

    Minimal_EEPROM_Lock();

}

void restore_settings()

{

    Minimal_EEPROM_Unlock();

    while(Minimal_FLASH_GetStatus()==FLASH_BUSY);

    boottobrew = (*(__IO uint32_t*)(EEPROM_BASE_ADDR + EEPROM_ADDR_BOOTTOBREW));

    while(Minimal_FLASH_GetStatus()==FLASH_BUSY);

    windup_guard = (*(__IO uint32_t*)(EEPROM_BASE_ADDR + EEPROM_ADDR_WINDUP_GUARD));

    while(Minimal_FLASH_GetStatus()==FLASH_BUSY);

    k_p = (*(__IO uint32_t*)(EEPROM_BASE_ADDR + EEPROM_ADDR_K_P));

    while(Minimal_FLASH_GetStatus()==FLASH_BUSY);

    k_i = (*(__IO uint32_t*)(EEPROM_BASE_ADDR + EEPROM_ADDR_K_I));

    while(Minimal_FLASH_GetStatus()==FLASH_BUSY);

    k_d = (*(__IO uint32_t*)(EEPROM_BASE_ADDR + EEPROM_ADDR_K_D));

    while(Minimal_FLASH_GetStatus()==FLASH_BUSY);

    setpoint_brew = (*(__IO uint32_t*)(EEPROM_BASE_ADDR + EEPROM_ADDR_BREWTEMP));

    while(Minimal_FLASH_GetStatus()==FLASH_BUSY);

    setpoint_steam = (*(__IO uint32_t*)(EEPROM_BASE_ADDR + EEPROM_ADDR_STEAMTEMP));    

    Minimal_EEPROM_Lock();

}

void user_input(uint16_t* to_modify)

{

    if(CHANGE_ELAPSED) {

        if(!GPIO_ReadInputDataBit(SW_UP) ) {

            CHANGE_RESET;

            (*to_modify)++;

        }

        else if(!GPIO_ReadInputDataBit(SW_DOWN) && (*to_modify) > 0) {

            CHANGE_RESET;

            (*to_modify)--;

        }

    }

}

void machine()

{

    uint8_t last_state = state;

    uint8_t sw_btn = !GPIO_ReadInputDataBit(SW_BTN);

    uint8_t sw_up = !GPIO_ReadInputDataBit(SW_UP);

    uint8_t sw_down = !GPIO_ReadInputDataBit(SW_DOWN);

    uint8_t sw_left = !GPIO_ReadInputDataBit(SW_LEFT);

    uint8_t sw_right = !GPIO_ReadInputDataBit(SW_RIGHT);

    switch(state)

    {

        // Idle state

        case STATE_IDLE:

        {

            // Write text to OLED

            // [ therm :: idle ]

            ssd1306_DrawString("therm :: idle ", 0, 40);

            pid_enabled = 0;

            char tempstr[6];

            itoa_fp(temp, temp_frac, tempstr);

            ssd1306_DrawString("Temp: ", 3, 40);

            ssd1306_DrawString("    ", 3, 72);

            ssd1306_DrawString(tempstr, 3, 72);

            ssd1306_drawlogo();

            switch(goto_mode) {

                case 2:

                {

                    ssd1306_DrawString("-> brew     ", 1, 40);

                } break;

                case 1:

                {

                    ssd1306_DrawString("-> setup    ", 1, 40);

                } break;

                case 0:

                {

                    ssd1306_DrawString("-> reset    ", 1, 40);

                } break;

            }

            // Button handler

            if(SW_BTN_PRESSED) {

                switch(goto_mode) {

                    case 2:

                        state = STATE_PREHEAT_BREW;

                        break;

                    case 1:

                        state = STATE_SETP;

                        break;

                    case 0:

                        state = STATE_IDLE;

                        break;

                    default:

                        state = STATE_PREHEAT_BREW;

                }

            }

            else if(SW_UP_PRESSED && goto_mode < 2) {

                goto_mode++;

            }

            else if(SW_DOWN_PRESSED && k_p > 0 && goto_mode > 0) {

                goto_mode--;

            }

            // Event Handler

            // N/A

        } break;

        case STATE_SETP:

        {

            // Write text to OLED

            // [ therm :: set p ]

            // [ p = 12         ]

            ssd1306_DrawString("Proportional", 0, 40);

            ssd1306_drawlogo();

            char tempstr[6];

            itoa(k_p, tempstr);

            ssd1306_DrawString("P=", 1, 45);

            ssd1306_DrawString("    ", 1, 57);

            ssd1306_DrawString(tempstr, 1, 57);

            ssd1306_DrawString("Press to accept", 3, 40);

            // Button handler

            if(SW_BTN_PRESSED) {

                state = STATE_SETI;

            }

        } break;

        case STATE_PREHEAT_STEAM:

        {

            // Write text to OLED

            // [ therm : preheating steam ]

            // [ 30 => 120 C           ]

            ssd1306_DrawString("Preheating...", 0, 40);

            ssd1306_drawlogo();

            draw_setpoint();

            pid_enabled = 1;

	    setpoint = setpoint_steam;

            // Button handler

            if(SW_BTN_PRESSED) {

                state = STATE_IDLE;

		save_setpoints(); // TODO: Check for mod

            }

            else {

                user_input(&setpoint_steam);

            }

            // Event Handler

            if(temp >= setpoint) {

                state = STATE_MAINTAIN_STEAM;

            }

        } break;

        case STATE_MAINTAIN_STEAM:

        {

            // Write text to OLED

            // [ therm : ready to steam ]

            // [ 30 => 120 C            ]

            ssd1306_DrawString("Ready to Steam!", 0, 40);

            ssd1306_drawlogo();

            draw_setpoint();

            pid_enabled = 1;

	    setpoint = setpoint_steam;

            // Button handler

            if(SW_BTN_PRESSED) {

                state = STATE_IDLE;

		save_setpoints(); // TODO: Check for mod

            }

            else {

                user_input(&setpoint_steam);

            }

            // Event Handler

            // N/A

        } break;

        // Something is terribly wrong

        default:

        {

            state = STATE_IDLE;

            pid_enabled = 0;

        } break;

    }

    if(last_state != state) {

        // Clear screen on state change

        goto_mode = 2;

        ssd1306_clearscreen();

    }

    // Last buttonpress

    sw_btn_last = sw_btn;

    sw_up_last = sw_up;

    sw_down_last = sw_down;

    sw_left_last = sw_left;

    sw_right_last = sw_right;

}

// Delay a number of systicks

void delay(__IO uint32_t nTime)

{

  TimingDelay = nTime;

  while(TimingDelay != 0);

}

// ISR-triggered decrement of delay and increment of tickcounter

void TimingDelay_Decrement(void)

{

  if (TimingDelay != 0x00)

  { 

    TimingDelay--;

  }

  ticks++;

}

void init_spi(void)

{

    SPI_InitTypeDef  SPI_InitStructure;

    // OLED IC

    SPI_Cmd(SPI1, DISABLE); 

    SPI_InitStructure.SPI_Direction = SPI_Direction_1Line_Tx;

    SPI_InitStructure.SPI_Mode = SPI_Mode_Master;

    SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b;

    SPI_InitStructure.SPI_CPOL = SPI_CPOL_High;

    SPI_InitStructure.SPI_CPHA = SPI_CPHA_2Edge;

    SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;

    SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_4;

    SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;

    SPI_InitStructure.SPI_CRCPolynomial = 7;

    SPI_Init(SPI1, &SPI_InitStructure);

    SPI_Cmd(SPI1, ENABLE);           /* Enable the SPI  */   

    // MAX IC

    SPI_Cmd(SPI2, DISABLE); 

    SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;

    SPI_InitStructure.SPI_Mode = SPI_Mode_Master;

    SPI_InitStructure.SPI_DataSize = SPI_DataSize_16b; // Andysworkshop

    SPI_InitStructure.SPI_CPOL = SPI_CPOL_Low; // From andysworkshop

    SPI_InitStructure.SPI_CPHA = SPI_CPHA_1Edge; // same

    SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;

    SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_8;

    SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;

    SPI_InitStructure.SPI_CRCPolynomial = 7;

    SPI_Init(SPI2, &SPI_InitStructure);

    SPI_Cmd(SPI2, ENABLE);           /* Enable the SPI */

}

void init_gpio(void) {

 GPIO_InitTypeDef GPIO_InitStruct;

  // Enable SPI clocks

  RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);

  RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI2, ENABLE);

  // Enable GPIO clocks

  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOC|RCC_AHBPeriph_GPIOB|RCC_AHBPeriph_GPIOA, ENABLE);

  // Enable DMA clocks (Is AHB even the right thing???)

  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE); // EMZ TODO get the right ones

  /*Configure GPIO pin : PC */

  GPIO_InitStruct.GPIO_Pin = GPIO_Pin_13;

  GPIO_InitStruct.GPIO_Mode = GPIO_Mode_OUT;

  GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;

  GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;

  GPIO_InitStruct.GPIO_Speed = GPIO_Speed_400KHz;

  GPIO_Init(GPIOC, &GPIO_InitStruct);

  /*Configure GPIO pin : PB */

  GPIO_InitStruct.GPIO_Pin = GPIO_Pin_1|GPIO_Pin_2|GPIO_Pin_10|GPIO_Pin_12 

                          |GPIO_Pin_9;

  GPIO_InitStruct.GPIO_Mode = GPIO_Mode_OUT;

  GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;

  GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;

  GPIO_InitStruct.GPIO_Speed = GPIO_Speed_400KHz;

  GPIO_Init(GPIOB, &GPIO_InitStruct);

  /*Configure GPIO pin : PA */

  GPIO_InitStruct.GPIO_Pin = GPIO_Pin_15;

  GPIO_InitStruct.GPIO_Mode = GPIO_Mode_OUT;

  GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;

  GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;

  GPIO_InitStruct.GPIO_Speed = GPIO_Speed_400KHz;

  GPIO_Init(GPIOA, &GPIO_InitStruct);

  /*Configure GPIO pin : PB */

  GPIO_InitStruct.GPIO_Pin = GPIO_Pin_3|GPIO_Pin_4|GPIO_Pin_5|GPIO_Pin_6 

                          |GPIO_Pin_7;

  GPIO_InitStruct.GPIO_Mode = GPIO_Mode_IN;

  GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;

  GPIO_Init(GPIOB, &GPIO_InitStruct);

  /** SPI1 GPIO Configuration  

  PA5   ------> SPI1_SCK

  PA7   ------> SPI1_MOSI

  */

  /*Enable or disable the AHB peripheral clock */

  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);

  /*Configure GPIO pin : PA: MOSI,SCK */

  GPIO_InitStruct.GPIO_Pin = GPIO_Pin_5|GPIO_Pin_7;

  GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;

  GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;

  GPIO_InitStruct.GPIO_Speed = GPIO_Speed_10MHz;

  GPIO_Init(GPIOA, &GPIO_InitStruct);

  /*Configure GPIO pin alternate function */

  * @brief  Update SystemCoreClock according to Clock Register Values

  *         The SystemCoreClock variable contains the core clock (HCLK), it can

  *         be used by the user application to setup the SysTick timer or configure

  *         other parameters.

  *           

  * @note   Each time the core clock (HCLK) changes, this function must be called

  *         to update SystemCoreClock variable value. Otherwise, any configuration

  *         based on this variable will be incorrect.         

  *     

  * @note   - The system frequency computed by this function is not the real 

  *           frequency in the chip. It is calculated based on the predefined 

  *           constant and the selected clock source:

  *             

  *           - If SYSCLK source is MSI, SystemCoreClock will contain the MSI 

  *             value as defined by the MSI range.

  *                                   

  *           - If SYSCLK source is HSI, SystemCoreClock will contain the HSI_VALUE(*)

  *                                              

  *           - If SYSCLK source is HSE, SystemCoreClock will contain the HSE_VALUE(**)

  *                          

  *           - If SYSCLK source is PLL, SystemCoreClock will contain the HSE_VALUE(**) 

  *             or HSI_VALUE(*) multiplied/divided by the PLL factors.

  *         

  *         (*) HSI_VALUE is a constant defined in stm32l1xx.h file (default value

  *             16 MHz) but the real value may vary depending on the variations

  *             in voltage and temperature.   

  *    

  *         (**) HSE_VALUE is a constant defined in stm32l1xx.h file (default value

  *              8 MHz), user has to ensure that HSE_VALUE is same as the real

  *              frequency of the crystal used. Otherwise, this function may

  *              have wrong result.

  *                

  *         - The result of this function could be not correct when using fractional

  *           value for HSE crystal.  

  * @param  None

  * @retval None

  */

void SystemCoreClockUpdate (void)

{

  uint32_t tmp = 0, pllmul = 0, plldiv = 0, pllsource = 0, msirange = 0;

  /* Get SYSCLK source -------------------------------------------------------*/

  tmp = RCC->CFGR & RCC_CFGR_SWS;

  switch (tmp)

  {

    case 0x00:  /* MSI used as system clock */

      msirange = (RCC->ICSCR & RCC_ICSCR_MSIRANGE) >> 13;

      SystemCoreClock = (32768 * (1 << (msirange + 1)));

      break;

    case 0x04:  /* HSI used as system clock */

      SystemCoreClock = HSI_VALUE;

      break;

    case 0x08:  /* HSE used as system clock */

      SystemCoreClock = HSE_VALUE;

      break;

    case 0x0C:  /* PLL used as system clock */

      /* Get PLL clock source and multiplication factor ----------------------*/

      pllmul = RCC->CFGR & RCC_CFGR_PLLMUL;

      plldiv = RCC->CFGR & RCC_CFGR_PLLDIV;

      pllmul = PLLMulTable[(pllmul >> 18)];

      plldiv = (plldiv >> 22) + 1;

      pllsource = RCC->CFGR & RCC_CFGR_PLLSRC;

      if (pllsource == 0x00)

      {

        /* HSI oscillator clock selected as PLL clock entry */

        SystemCoreClock = (((HSI_VALUE) * pllmul) / plldiv);

      }

      else

      {

        /* HSE selected as PLL clock entry */

        SystemCoreClock = (((HSE_VALUE) * pllmul) / plldiv);

      }

      break;

    default: /* MSI used as system clock */

      msirange = (RCC->ICSCR & RCC_ICSCR_MSIRANGE) >> 13;

      SystemCoreClock = (32768 * (1 << (msirange + 1)));

      break;

  }

  /* Compute HCLK clock frequency --------------------------------------------*/

  /* Get HCLK prescaler */

  tmp = AHBPrescTable[((RCC->CFGR & RCC_CFGR_HPRE) >> 4)];

  /* HCLK clock frequency */

  SystemCoreClock >>= tmp;

}

/**

  * @brief  Configures the System clock frequency, AHB/APBx prescalers and Flash 

  *         settings.

  * @note   This function should be called only once the RCC clock configuration  

  *         is reset to the default reset state (done in SystemInit() function).             

  * @param  None

  * @retval None

  */

static void SetSysClock(void)

{

  __IO uint32_t StartUpCounter = 0, HSEStatus = 0;

  /* SYSCLK, HCLK, PCLK2 and PCLK1 configuration ---------------------------*/

  /* Enable HSE */

  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 64-bit access */

    FLASH->ACR |= FLASH_ACR_ACC64;

    /* Enable Prefetch Buffer */

    FLASH->ACR |= FLASH_ACR_PRFTEN;

    /* Flash 1 wait state */

    FLASH->ACR |= FLASH_ACR_LATENCY;

    /* Power enable */

    RCC->APB1ENR |= RCC_APB1ENR_PWREN;

    /* Select the Voltage Range 1 (1.8 V) */

    PWR->CR = PWR_CR_VOS_0;

    /* Wait Until the Voltage Regulator is ready */

    while((PWR->CSR & PWR_CSR_VOSF) != RESET)

    {

    }

    /* HCLK = SYSCLK /1*/

    RCC->CFGR |= (uint32_t)RCC_CFGR_HPRE_DIV1;

    /* PCLK2 = HCLK /1*/

    RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE2_DIV1;

    /* PCLK1 = HCLK /1*/

    RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE1_DIV1;

    /*  PLL configuration */

    RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_PLLSRC | RCC_CFGR_PLLMUL |

                                        RCC_CFGR_PLLDIV));

    RCC->CFGR |= (uint32_t)(RCC_CFGR_PLLSRC_HSE | RCC_CFGR_PLLMUL24 | RCC_CFGR_PLLDIV3);

    /* 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

  {

//	while(1);

    /* If HSE fails to start-up, the application will have wrong clock

       configuration. User can add here some code to deal with this error */

  }

}

/**