a problem with set ClockDivision

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);

 

}