Timer2 Configuration

[DOSS FOF]

Posted on May 15, 2017 at 10:47

I'm working on STM32 nucleo432lkc. I'm trying to divide the MSI frequency for the timer by 50 but when I try this , i get nothing on the ouput of the pin. Below is the timer 2 code :

void TIM2_init(void)

{

      TIM_ClockConfigTypeDef sClockSourceConfig;

      TIM_MasterConfigTypeDef sMasterConfig;

    __TIM2_CLK_ENABLE();

    TIM_init_struct.Instance = TIM2;

    TIM_init_struct.Init.Prescaler = 0 ;//40000;

    TIM_init_struct.Init.CounterMode = TIM_COUNTERMODE_UP;

    TIM_init_struct.Init.Period = 0 ;//491;

    TIM_init_struct.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;

    TIM_init_struct.Init.RepetitionCounter = 0;

    //HAL_TIM_Base_Init(&TIM_init_struct);

    if(HAL_TIM_Base_Init(&TIM_init_struct)== HAL_OK)

      {

        /* Start the TIM time Base generation in interrupt mode */

        HAL_TIM_Base_Start_IT(&TIM_init_struct);

      }

    HAL_NVIC_SetPriority(TIM2_IRQn, 0, 1);

    HAL_NVIC_EnableIRQ(TIM2_IRQn);

     sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;

      if (HAL_TIM_ConfigClockSource(&TIM_init_struct, &sClockSourceConfig) != HAL_OK)

      {

          TIM_Error_Handler();

      }

      sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;

      sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;

      if (HAL_TIMEx_MasterConfigSynchronization(&TIM_init_struct, &sMasterConfig) != HAL_OK)

      {

          TIM_Error_Handler();

      }

}

void TIM2_IRQHandler()

{

    //}

     HAL_TIM_IRQHandler(&TIM_init_struct);

}

#include 'stdbool.h'

bool test = false;

void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)

{

    int timerValue =  HAL_RCC_GetSysClockFreq();

    if (test) {

        HAL_GPIO_WritePin(GPIOB, GPIO_PIN_0, GPIO_PIN_RESET);

        test = false;

    } else {

        HAL_GPIO_WritePin(GPIOB, GPIO_PIN_0, GPIO_PIN_SET);

        test = true;

    }

//    HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_0);

    HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_3);

}

[RomainR.]

Posted on May 15, 2017 at 17:08

Hello,

It would seem in your code that you do not configure the value of your timer period?

TIM_init_struct.Init.Period = 0; // 491;�?

What is your requirement in your application for the interruptions period?

Could you verify ?

Best regards

[DOSS FOF]

Posted on May 16, 2017 at 09:17

Hello Romain,

In fact I forgot and pasted previous version. But the real values were this:

    TIM_init_struct.Init.Prescaler = 1 ;

    TIM_init_struct.Init.CounterMode = TIM_COUNTERMODE_UP;

    TIM_init_struct.Init.Period = 50 ;

    TIM_init_struct.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;

    TIM_init_struct.Init.RepetitionCounter = 0;

The clock frequency is 38.4 MHz and tried to divided by  2x51 in that way. But when I run the programme 

, I trully get the call back function 'void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)',

but the GPIO didn't work. In contrast I realized that another function inside the callback works.

That is the GPIO intialization :

         GPIO_InitTypeDef GPIO_init_struct;

        GPIO_init_struct.Pin = GPIO_PIN_3 |GPIO_PIN_7;

        GPIO_init_struct.Mode = GPIO_MODE_OUTPUT_PP;

        GPIO_init_struct.Pull = GPIO_NOPULL;

        GPIO_init_struct.Speed =  GPIO_SPEED_FREQ_HIGH 

        HAL_GPIO_Init(GPIOB, &GPIO_init_struct);

Notice: the values greater than 100 (TIM_init_struct.Init.Period = 50) work.

[RomainR.]

Posted on May 17, 2017 at 16:53

Hello,

Assuming your Timer 2 input clock is 4MHz, this means that with the following settings:

TIM_init_struct.Init.Prescaler = 1;
TIM_init_struct.Init.Period = 50;�?�?

The counting resolution of your timer is about 26ns.

With a value of period = 50, you will get an overflow interrupt every 1.3μs (26ns x 50) For a value of period = 100, you will get an interrupt every 2.6μs.

period = (Timer Clock frequency / Timer prescaler x period frequency) - 1

How do you visualize the GPIO that is supposed to make the toggle in the Timer Callback function with such a fast period of 1.3μs? If you use an oscilloscope you should be able to see the change of state of this output?

Again, I ask you the same question, what are your specificity in your application for Timer 2 interrupt point of view ?

You should fix this point and then configure your timer according.

Regards

[DOSS FOF]

Posted on May 19, 2017 at 10:29

Hello Romain,

Another notice , I have managed to generate 48KHz for GPIO and 4.8 KHz for the DACs. Whatever the SPI configuration (Baudrate ) I always have this differences : Dacs signal 10 times lower than Timer interruption. I don't understand this problem. 

Dac maximum speed is 50MHz in the datasheet. Concerning SPI_DMA I have tried it but no success, may be the configuaration is not well done. I will bring the code next time

Thanks

[DOSS FOF]

Posted on May 19, 2017 at 11:04

The original post was too long to process during our migration. Please click on the provided URL to read the original post. https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006I6sE&d=%2Fa%2F0X0000000bx3%2FV1JY9.rDQ0.kkr5U_kYYanpWThlyVIRwNvNpK_VG_vg&asPdf=false