How to Update Timer period ???

[lizerd]

Posted on July 23, 2011 at 21:37

I have tried to update Timer 2 with new period value without any good resualt.

I use two channels on Timer 2 as PWM outputs, The PWM works fine, But when i tries to update the period value in timer 2 the PWM signals disappears. sometimes i manage to update the timer with a period value that is larger then the one before. but never a smaller value. please i really would like some help with this one. i have tried this for to long now.My update code so far.     /* Time Base configuration */     TIM_TimeBaseStructure.TIM_Period = 1000;     TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);     TIM_ClearFlag(TIM2, TIM_FLAG_CC3);     TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;     TIM_OCInitStructure.TIM_Pulse =  500;     TIM_OC3Init(TIM2, &TIM_OCInitStructure);And the Timer initilize code     // Timer clock     RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA |RCC_APB2Periph_AFIO, ENABLE);     RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);     /* Time Base configuration */     TIM_TimeBaseStructure.TIM_Period = 2000;     TIM_TimeBaseStructure.TIM_Prescaler = 0;     TIM_TimeBaseStructure.TIM_ClockDivision = 0;     TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;         TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);       /* PWM1 Mode configuration: Channel1 */     TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;     TIM_OCInitStructure.TIM_Pulse = 1000;     TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;     TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;     TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;       // Motor A channel     TIM_OC2Init(TIM2, &TIM_OCInitStructure);     TIM_OC2PreloadConfig(TIM2, TIM_OCPreload_Enable);     // Motor B channel     TIM_OC3Init(TIM2, &TIM_OCInitStructure);     TIM_OC3PreloadConfig(TIM2, TIM_OCPreload_Enable);     TIM_ARRPreloadConfig(TIM2, ENABLE);       /* TIM1 enable counter */     TIM_Cmd(TIM2, ENABLE);     /* TIM1 Main Output Enable */     TIM_CtrlPWMOutputs(TIM2, ENABLE);

[lizerd]

Posted on July 24, 2011 at 16:48

I found the solution, it sure is not the right one

because i need to reset the timer before and after (TIM_SetCounter(TIM2, 0);) to make it work, and it do not work every time. Must be a safer and better way to do it ?? void MotorPWM_HighFreq(void) {     TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;     TIM_OCInitTypeDef  TIM_OCInitStructure;     GPIO_InitTypeDef GPIO_InitStructure;     TIM_SetCounter(TIM2, 0);     /* Time Base configuration */     TIM_TimeBaseStructure.TIM_Period = 999;     TIM_TimeBaseStructure.TIM_Prescaler = 0;     TIM_TimeBaseStructure.TIM_ClockDivision = 0;         TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);     TIM_SetCounter(TIM2, 0); }