STMF4 Timer external clock mode 1

francesco b · ‎2016-12-15

Posted on December 15, 2016 at 10:54

Hi everyone,

i want to count the positive edges of a pulsesignal on PA6 using a Timer with external clock.

To test the functionality i generate the signal and outputport is PA8. PA8 is linked with PA6.

After several tries it still doesn't count and i don't know why anymore.

Thanks if anyone knows a hint

Here the most important parts of the code:

GPIO_InitStruct.Pin = GPIO_PIN_6;

GPIO_InitStruct.Mode = GPIO_MODE_INPUT;

GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;

GPIO_InitStruct.Alternate = GPIO_AF2_TIM3; //Signal assigned to AF2 TIM3

GPIO_InitStruct.Pin = GPIO_PIN_8;

GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;

GPIO_InitStruct.Pull = GPIO_PULLDOWN;

GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;

HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

__TIM3_CLK_ENABLE();

hTim3.Instance = TIM3;

hTim3.Init.Prescaler = 40;

hTim3.Init.CounterMode = TIM_COUNTERMODE_UP;

hTim3.Init.Period = 700;

hTim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;

hTim3.Init.RepetitionCounter = 0;

HAL_TIM_Base_Init(&hTim3);

TIM_ClockConfigTypeDef TimClock;

TimClock.ClockSource = TIM_CLOCKSOURCE_TI1; //ETRMODE1 oder TI1

TimClock.ClockPolarity = TIM_CLOCKPOLARITY_RISING; //polarity of TIx clock source

TimClock.ClockPrescaler = TIM_CLOCKPRESCALER_DIV1;

HAL_TIM_ConfigClockSource(&hTim3,&TimClock);

TIM_SlaveConfigTypeDef SlaveConfig;

SlaveConfig.SlaveMode = TIM_SLAVEMODE_EXTERNAL1; //External Source als Clock

SlaveConfig.InputTrigger = TIM_TS_TI1FP1; //

SlaveConfig.TriggerFilter = 0; //No filter needed

SlaveConfig.TriggerPolarity = TIM_TRIGGERPOLARITY_RISING; //Counting on rising edge

SlaveConfig.TriggerPrescaler = TIM_TRIGGERPRESCALER_DIV1; //No Prescaler

HAL_TIM_SlaveConfigSynchronization(&hTim3, &SlaveConfig);

HAL_TIM_Base_Start(&hTim3);

while (1)

{

HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);

HAL_Delay(50);

HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_SET);

HAL_Delay(50);

iz++;

ic = __HAL_TIM_GET_COUNTER(&hTim3);

if (ic==50){

HAL_GPIO_WritePin(GPIOD, GPIO_PIN_12, GPIO_PIN_SET);

}

Seb · ‎2016-12-15

Posted on December 15, 2016 at 12:15

Have little experience in using a timer with external clock this way as I like to use peripheral for various usages at same time. Until someone gives the right way to do it, 2 alternative ways:

If the frequency of the rising edge is reasonable, use a TIMER with internal clock reference, then inject 1 to 4 signals to the CC channels of the timer. The timer will 'input capture' when a rise or fall edge occured, and using the corresponding interrupt, you can increase a counter (a global variable). This way, you can also check the duty cycle, compare between up to 4 signals, generate delayed pulses using the 'output compare' mode. (this can be fun to use an op-amp with dynamic switches to run an integrator for example).

Another alternative way is to use EXTI (this is the simplest way).

Good luck!

waclawek.jan · ‎2016-12-15

Posted on December 15, 2016 at 13:49

GPIO_InitStruct.Mode = GPIO_MODE_INPUT;

I don't Cube: is this OK for AF?

JW