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STM32F4 Discover Pulse Counting

Question asked by traud.jason on Nov 11, 2015
Latest reply on Nov 12, 2015 by Clive One
My end goal is that I want to count pulses that occur on one of the inputs on the STM32F4 Discovery dev board and I'm having issues.

I found this post that seems to be doing what I want, but it's not quite working. I have data spitting out of UART4 but it's non-nonsensical.  Perhaps it's just counting up and disregarding the voltage on PD12?

https://my.st.com/public/STe2ecommunities/mcu/Lists/STM32Discovery/Flat.aspx?RootFolder=https%3a%2f%2fmy%2est%2ecom%2fpublic%2fSTe2ecommunities%2fmcu%2fLists%2fSTM32Discovery%2fSTM32F4%20Timer%20External%20Pulse%20counting&FolderCTID=0x01200200770978C69A1141439FE559EB459D75800084C20D8867EAD444A5987D47BE638E0F&currentviews=6201

Platform:
STM32F407VG

void TIM4_Configuration(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
    TIM_ICInitTypeDef TIM_ICInitStructure;
 
    /* GPIOD clock enable */
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
 
    /* TIM4 clock enable */
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);
 
    /* GPIOA Configuration: TIM4 CH1 (PD12) */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;                        // Input/Output controlled by peripheral
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;                        // Button to ground expectation
    GPIO_Init(GPIOD, &GPIO_InitStructure);
 
    /* Connect TIM4 pins to AF */
    GPIO_PinAFConfig(GPIOD, GPIO_PinSource12, GPIO_AF_TIM4);
 
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4,ENABLE);
 
    //  Time initialization
    TIM_TimeBaseInitStructure.TIM_ClockDivision = TIM_CKD_DIV1;         //Control with dead zone.
    TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;     //Counter direction
    TIM_TimeBaseInitStructure.TIM_Prescaler = 84-1;                     //Timer clock = sysclock /(TIM_Prescaler+1) = 2M
    TIM_TimeBaseInitStructure.TIM_RepetitionCounter = 0;
    TIM_TimeBaseInitStructure.TIM_Period = 0xFFFF;
 
    // Period = (TIM counter clock / TIM output clock) - 1 = 40Hz
    TIM_TimeBaseInit(TIM4,&TIM_TimeBaseInitStructure);
    TIM_ICInitStructure.TIM_Channel = TIM_Channel_1;
    TIM_ICInitStructure.TIM_ICFilter = 0;
    TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
    TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
    TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
    TIM_ICInit(TIM4,&TIM_ICInitStructure);
 
    // Turn on the counter
    TIM_Cmd(TIM4,ENABLE);
}

int main()
{
    char str[120];
    char ToABuffer[10]; // Debug prints
 
    System_Setup();
    UART4_Write_Byte(0xFF) ;
    mainDelayTimer = 5000 ;
 
    while(1){
 
        //UART_Write_Byte(0xFF) ;
 
        if (mainDelayTimer < 1) {
            mainDelayTimer = 5000 ;
 
            x_dot = TIM_GetCounter(TIM4);
            itoa(ToABuffer, x_dot, 10) ;
            UART4_Write_String(ToABuffer) ;
            UART4_Write_String("\r\n") ;
        }
    }
}

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