// STM32 TIM2 4 Channel Input Capture STM32F0-Discovery - sourcer32@gmail.com
 
#include "stm32f0xx.h"
#include "stm32f0_discovery.h"
 
//**************************************************************************************
 
void TIM2_Config(void)
{
  TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
  TIM_ICInitTypeDef        TIM_ICInitStructure;
 
  /* TIM2 Periph clock enable */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
 
  /* TIM2 Configuration */
  TIM_DeInit(TIM2);
 
  /* Time base configuration */
  TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);
  TIM_TimeBaseStructure.TIM_Prescaler = (SystemCoreClock / 1000000) - 1; // 1 MHz, from 48 MHz
  TIM_TimeBaseStructure.TIM_Period = 0xFFFFFFFF; // Maximal, TIM2 is 32-bit counter
  TIM_TimeBaseStructure.TIM_ClockDivision = 0x0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
  TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
 
  TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising; // Rising/Falling/BothEdge
  TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
  TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
  TIM_ICInitStructure.TIM_ICFilter = 0x0;
 
  TIM_ICInitStructure.TIM_Channel = TIM_Channel_1;
  TIM_ICInit(TIM2, &TIM_ICInitStructure);
  TIM_ICInitStructure.TIM_Channel = TIM_Channel_2;
  TIM_ICInit(TIM2, &TIM_ICInitStructure);
  TIM_ICInitStructure.TIM_Channel = TIM_Channel_3;
  TIM_ICInit(TIM2, &TIM_ICInitStructure);
  TIM_ICInitStructure.TIM_Channel = TIM_Channel_4;
  TIM_ICInit(TIM2, &TIM_ICInitStructure);
 
  /* TIM1 enable counter */
  TIM_Cmd(TIM2, ENABLE);
 
  /* Enable the CCx Interrupt Request */
  TIM_ITConfig(TIM2, TIM_IT_CC1 | TIM_IT_CC2 | TIM_IT_CC3 | TIM_IT_CC4, ENABLE);
}
 
//**************************************************************************************
 
volatile uint32_t Freq[4];
 
void TIM2_IRQHandler(void)
{
    uint32_t Current, Delta;
    static uint32_t Last[4];
     
  if (TIM_GetITStatus(TIM2, TIM_IT_CC1) != RESET)
    {
        /* Clear TIM2_CH1 Capture compare interrupt pending bit */
        TIM_ClearITPendingBit(TIM2, TIM_IT_CC1);
 
        Current = TIM_GetCapture1(TIM2);
        Delta = Current - Last[0];
        Last[0] = Current;
        if (Delta)
            Freq[0] = 1000000 / Delta; // 1MHz clock
         
        // ..
    }
     
  if (TIM_GetITStatus(TIM2, TIM_IT_CC2) != RESET)
    {
        /* Clear TIM2_CH2 Capture compare interrupt pending bit */
        TIM_ClearITPendingBit(TIM2, TIM_IT_CC2);
 
        Current = TIM_GetCapture2(TIM2);
        Delta = Current - Last[1];
        Last[1] = Current;
        if (Delta)
            Freq[1] = 1000000 / Delta; // 1MHz clock
         
        // ..
    }
     
  if (TIM_GetITStatus(TIM2, TIM_IT_CC3) != RESET)
    {
        /* Clear TIM2_CH3 Capture compare interrupt pending bit */
        TIM_ClearITPendingBit(TIM2, TIM_IT_CC3);
 
        Current = TIM_GetCapture3(TIM2);
        Delta = Current - Last[2];
        Last[2] = Current;
        if (Delta)
            Freq[2] = 1000000 / Delta; // 1MHz clock
         
        // ..
    }
     
  if (TIM_GetITStatus(TIM2, TIM_IT_CC4) != RESET)
    {
        /* Clear TIM2_CH4 Capture compare interrupt pending bit */
        TIM_ClearITPendingBit(TIM2, TIM_IT_CC4);
 
        Current = TIM_GetCapture4(TIM2);
        Delta = Current - Last[3];
        Last[3] = Current;
        if (Delta)
            Freq[3] = 1000000 / Delta; // 1MHz clock
         
        // ..
    }
}
 
//**************************************************************************************
 
void NVIC_Config(void)
{
  NVIC_InitTypeDef NVIC_InitStructure;
 
  /* Enable and set TIM2 Interrupt */
  NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPriority = 0x00;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);
}
 
//**************************************************************************************
 
void GPIO_Config(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;
 
  /* GPIOA Periph clock enable */
  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);
 
  /* Configure TIM2 input */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5 | GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3;
  GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
 
  /* Connect TIM pins to AF2 */
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_2); // TIM2_CH1 PA5
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource1, GPIO_AF_2); // TIM2_CH2 PA1
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_2); // TIM2_CH3 PA2
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_2); // TIM2_CH4 PA3
}
 
//**************************************************************************************
 
int main(void)
{
  NVIC_Config();
 
  GPIO_Config();
 
  TIM2_Config();
 
  while(1); /* Infinite loop */
}