a problem with set ClockDivision

[hossein hosseini]

Posted on March 28, 2018 at 11:44

hi dears .

i am trying to use toggle mode in stm32f103re with IAR and cmsis.

When do i set  TIM_ClockDivision  in my code , the duty  is 50% , but i know i set the Compare4 to other value in time base init , and it does not be 50%.

And when i put this line to comment, the code do correctly.it does not be 50% duty cycle.i see that with oscope.

i dont know why this activity occer.

the register in default mode has 0x0000 value , and when i comment the line of set clockDivision , it has zero value,and if i  uncommented this line and set to zero , the code do the activity wrong.why??

i mean this line:

TIM_TimeBaseStructure.TIM_ClockDivision = 0;

this is my code with the uncommented line that there is above:

thanks alot.

#include 'stm32f10x.h'#include 'stm32f10x_gpio.h'  // for Enable LCD#include 'stm32f10x_rcc.h'   //for Enable LCD#include 'stm32f10x_tim.h'#include 'LCDLib.h'#include 'delay.h'void tim_init(void);void GPIO_init(void);int i = 0;int main(){   lcd_init();  lcdPutString ('Believe Your Dreams.');      GPIO_init();  tim_init();      while(1){   for(i = 0 ; i<=200 ; i=50)   {    TIM_SetCompare4(TIM3, i);     lcdGoxy(1 , 4);     lcdPutInt(TIM_GetCounter(TIM3));    delay_ms(80);    }//   for(i = 500 ; i>=0 ; i--)//   {//    TIM_SetCompare4(TIM3, i); //    delay_ms(8); //   }      }    }void tim_init(){          RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);    TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;  TIM_OCInitTypeDef  TIM_OCInitStructure;      TIM_TimeBaseStructure.TIM_Prescaler = 30;  TIM_TimeBaseStructure.TIM_Period = 200;    TIM_TimeBaseStructure.TIM_ClockDivision = 0;  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);          TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Toggle   ;  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;  TIM_OCInitStructure.TIM_Pulse = 0;  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;    TIM_OC4Init(TIM3, &TIM_OCInitStructure);  TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Enable);   TIM_Cmd(TIM3, ENABLE);   }void GPIO_init(void){      RCC_APB2PeriphClockCmd ( RCC_APB2Periph_GPIOC| RCC_APB2Periph_AFIO, ENABLE );      GPIO_InitTypeDef gpioAa;       gpioAa.GPIO_Mode = GPIO_Mode_AF_PP ;  gpioAa.GPIO_Pin = GPIO_Pin_9;  gpioAa.GPIO_Speed = GPIO_Speed_50MHz;    GPIO_Init( GPIOC,  &gpioAa );  GPIO_PinRemapConfig(GPIO_FullRemap_TIM3, ENABLE);  }

[Tesla DeLorean]

Posted on March 28, 2018 at 13:40

Auto/local variables/structures have random values, downstream code may malfunction if all fields have not been initialized.

Use the form

  TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure = {0};

  TIM_OCInitTypeDef  TIM_OCInitStructure = {0};  

[hossein hosseini]

Posted on March 29, 2018 at 20:36

yeah , got it.

but when is do that, i think the toggle mode dose not work.

i mean , when i set a value to CCR4 register :

  TIM_OCInitStructure.TIM_Pulse = 30;

however i have 50% duty cycle in a period.

the period value is 200 and i know that  is wrong in toggle mode,but when i comment the line TIM_ClockDivision , the toggle mode work correct.

i think when the timer value = pulse  then toggle happent.

but here toggle happent at half of period always.

when TIM_ClockDivision compile with other line.

when TIM_ClockDivision not  compile with other line.and in my idea this activity is true in output compare mode toggle.

thank you.

[Tesla DeLorean]

Posted on March 29, 2018 at 21:41

Yes, does sound a bit odd, not really something I'm looking to replicate/validate on an F1