STM32F4: Generating a sine wave

void TIM2_IRQHandler(void)

{

if (TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET)

{

GPIO_SetBits(GPIOD, GPIO_Pin_13);

PWM_SetDC(1,pulse_width);

// Calculate a new pulse width

phase_accumulator+=R;

angle=(uint8_t)(phase_accumulator>>24);

pulse_width = sinetable[angle];

TIM_ClearITPendingBit(TIM2, TIM_IT_Update);

GPIO_ResetBits(GPIOD, GPIO_Pin_13);

}

}




/* Includes ------------------------------------------------------------------*/
#include "stm32f4_discovery.h"
#include <stdio.h>

/* Private typedef -----------------------------------------------------------*/
GPIO_InitTypeDef  GPIO_InitStructure;
USART_InitTypeDef USART_InitStructure;
TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
TIM_OCInitTypeDef  TIM_OCInitStructure;
/* Private define ------------------------------------------------------------*/
// This is the magic number used to increment the phase accumulator
#define R 107374182
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
uint16_t sinetable[]  = { 
  127,130,133,136,139,143,146,149,152,155,158,161,164,167,170,173,176,178,181,184,187,190,192,195,198,200,203,205,208,210,212,215,217,219,221,223,225,227,229,231,233,234,236,238,239,240,
  242,243,244,245,247,248,249,249,250,251,252,252,253,253,253,254,254,254,254,254,254,254,253,253,253,252,252,251,250,249,249,248,247,245,244,243,242,240,239,238,236,234,233,231,229,227,225,223,
  221,219,217,215,212,210,208,205,203,200,198,195,192,190,187,184,181,178,176,173,170,167,164,161,158,155,152,149,146,143,139,136,133,130,127,124,121,118,115,111,108,105,102,99,96,93,90,87,84,81,78,
  76,73,70,67,64,62,59,56,54,51,49,46,44,42,39,37,35,33,31,29,27,25,23,21,20,18,16,15,14,12,11,10,9,7,6,5,5,4,3,2,2,1,1,1,0,0,0,0,0,0,0,1,1,1,2,2,3,4,5,5,6,7,9,10,11,12,14,15,16,18,20,21,23,25,27,29,31,
  33,35,37,39,42,44,46,49,51,54,56,59,62,64,67,70,73,76,78,81,84,87,90,93,96,99,102,105,108,111,115,118,121,124
};
uint16_t pulse_width = 128;
uint32_t phase_accumulator = 0;
uint8_t angle = 0;
/* Private function prototypes -----------------------------------------------*/
void TIM_Config(void);
void PWM_Config(int period);
void PWM_SetDC(uint16_t channel,uint16_t dutycycle);
void Delay(__IO uint32_t nCount);
void LED_Config(void);
void INTTIM_Config(void);
/* Private functions ---------------------------------------------------------*/



void TIM2_IRQHandler(void)
{
  if (TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET)
  {
    GPIO_SetBits(GPIOD, GPIO_Pin_13);
    PWM_SetDC(1,pulse_width);
    // Calculate a new pulse width
    phase_accumulator+=R;
    angle=(uint8_t)(phase_accumulator>>24);
    pulse_width = sinetable[angle];
    TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
    GPIO_ResetBits(GPIOD, GPIO_Pin_13);
  }
}
/**
  * @brief  Main program
  * @param  None
  * @retval None
  */
int main(void)
{
  
  /* TIM Configuration */
  TIM_Config();
  /* LED Configuration */
  LED_Config();
  /* PWM Configuration */
  PWM_Config(256);
  /* Sampling rate timer */
  INTTIM_Config();

  PWM_SetDC(1,128);
  PWM_SetDC(2,128);
  PWM_SetDC(3,128);
  PWM_SetDC(4,128);
  while (1)
  {
    // Wait for sampling clock to overflow
    if (TIM_GetFlagStatus(TIM2, TIM_FLAG_Update) != RESET)
    {
      
    }
    
  }
}

/**
  * @brief  Configure the TIM3 Ouput Channels.
  * @param  None
  * @retval None
  */
void TIM_Config(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;

  /* TIM3 clock enable */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

  /* GPIOC and GPIOB clock enable */
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC | RCC_AHB1Periph_GPIOB, ENABLE);
  
  /* GPIOC Configuration: TIM3 CH1 (PC6) and TIM3 CH2 (PC7) */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7 ;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;
  GPIO_Init(GPIOC, &GPIO_InitStructure); 
  
  /* GPIOB Configuration:  TIM3 CH3 (PB0) and TIM3 CH4 (PB1) */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;
  GPIO_Init(GPIOB, &GPIO_InitStructure); 

  /* Connect TIM3 pins to AF2 */  
  GPIO_PinAFConfig(GPIOC, GPIO_PinSource6, GPIO_AF_TIM3);
  GPIO_PinAFConfig(GPIOC, GPIO_PinSource7, GPIO_AF_TIM3); 
  GPIO_PinAFConfig(GPIOB, GPIO_PinSource0, GPIO_AF_TIM3);
  GPIO_PinAFConfig(GPIOB, GPIO_PinSource1, GPIO_AF_TIM3); 
}

void PWM_Config(int period)
{
  uint16_t PrescalerValue = 0;
  /* -----------------------------------------------------------------------
    TIM3 Configuration: generate 4 PWM signals with 4 different duty cycles.
    
    In this example TIM3 input clock (TIM3CLK) is set to 2 * APB1 clock (PCLK1), 
    since APB1 prescaler is different from 1.   
      TIM3CLK = 2 * PCLK1  
      PCLK1 = HCLK / 4 
      => TIM3CLK = HCLK / 2 = SystemCoreClock /2
          
    To get TIM3 counter clock at 28 MHz, the prescaler is computed as follows:
       Prescaler = (TIM3CLK / TIM3 counter clock) - 1
       Prescaler = ((SystemCoreClock /2) /28 MHz) - 1
                                              
    To get TIM3 output clock at 30 KHz, the period (ARR)) is computed as follows:
       ARR = (TIM3 counter clock / TIM3 output clock) - 1
           = 665

    Note: 
     SystemCoreClock variable holds HCLK frequency and is defined in system_stm32f4xx.c file.
     Each time the core clock (HCLK) changes, user had to call SystemCoreClockUpdate()
     function to update SystemCoreClock variable value. Otherwise, any configuration
     based on this variable will be incorrect.    
  ----------------------------------------------------------------------- */  

  /* No prescale, run at maximum frequency */
  PrescalerValue = 0;

  /* Time base configuration */
  TIM_TimeBaseStructure.TIM_Period = period;
  TIM_TimeBaseStructure.TIM_Prescaler = PrescalerValue;
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

  TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

  /* PWM1 Mode configuration: Channel1 */
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = 0;
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

  TIM_OC1Init(TIM3, &TIM_OCInitStructure);

  TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);

  /* PWM1 Mode configuration: Channel2 */
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = 0;

  TIM_OC2Init(TIM3, &TIM_OCInitStructure);

  TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);

  /* PWM1 Mode configuration: Channel3 */
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = 0;

  TIM_OC3Init(TIM3, &TIM_OCInitStructure);

  TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Enable);

  /* PWM1 Mode configuration: Channel4 */
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = 0;

  TIM_OC4Init(TIM3, &TIM_OCInitStructure);

  TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Enable);

  TIM_ARRPreloadConfig(TIM3, ENABLE);

  /* TIM3 enable counter */
  TIM_Cmd(TIM3, ENABLE);
}

void PWM_SetDC(uint16_t channel,uint16_t dutycycle)
{
  if (channel == 1)
  {
    TIM3->CCR1 = dutycycle;
  }
  else if (channel == 2)
  {
    TIM3->CCR2 = dutycycle;
  }
  else if (channel == 3)
  {
    TIM3->CCR3 = dutycycle;
  }
  else 
  {
    TIM3->CCR4 = dutycycle;
  }
}

void LED_Config(void)
{
  /* GPIOD Periph clock enable */
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);

  /* Configure PD12, PD13, PD14 and PD15 in output pushpull mode */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12 | GPIO_Pin_13| GPIO_Pin_14| GPIO_Pin_15;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
  GPIO_Init(GPIOD, &GPIO_InitStructure);

}

void INTTIM_Config(void)
{
  NVIC_InitTypeDef NVIC_InitStructure;
  /* Enable the TIM2 gloabal Interrupt */
  NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);

  /* TIM2 clock enable */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
  /* Time base configuration */
  TIM_TimeBaseStructure.TIM_Period = 10 - 1;  // 1 MHz down to 100 KHz
  TIM_TimeBaseStructure.TIM_Prescaler = 84 - 1; 
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
  TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
  /* TIM IT enable */
  TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);
  /* TIM2 enable counter */
  TIM_Cmd(TIM2, ENABLE);
}

/**
  * @brief  Delay Function.
  * @param  nCount:specifies the Delay time length.
  * @retval None
  */
void Delay(__IO uint32_t nCount)
{
  while(nCount--)
  {
  }
}