TIM3 Issue in STM32F215

[thirukannan]

Posted on June 05, 2014 at 14:30

Hi,

I am using TIM3(PC6 to PC9) for PWM output in STM32F215. In this I want three 50Hz PWM signals and one 8KHz signal. So I have configured PC7,PC8,PC9 as 50Hz PWM  signals. For this i have assigned

PrescalerValue_50 = (uint16_t) ((SystemCoreClock/2 ) / 33335) - 1;

And I have configured PC6 as 80KHz PWM signal.For this i have assigned

PrescalerValue_10 = (uint16_t) ((SystemCoreClock/2 ) / 5000000) - 1;

But i am getting 8KHz in all pins. What is problem i do'nt know. Please help me asap. Below is my code void TIM_Config(void) {     GPIO_InitTypeDef GPIO_InitStructure;     /* TIM3 clock enable */     RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);     /* GPIOC clock enable */     RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);     /* GPIOC Configuration: TIM3 CH1 (PC6), TIM3 CH2 (PC7), TIM3 CH3 (PC8) and TIM3 CH4 (PC9) */     GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7 | GPIO_Pin_8 | GPIO_Pin_9;     GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;     GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;     GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;     GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;     GPIO_Init(GPIOC, &GPIO_InitStructure);     /* Connect TIM3 pins to AF2 */       //GPIO_PinAFConfig(GPIOC, GPIO_PinSource6, GPIO_AF_TIM3);     GPIO_PinAFConfig(GPIOC, GPIO_PinSource7, GPIO_AF_TIM3);     GPIO_PinAFConfig(GPIOC, GPIO_PinSource8, GPIO_AF_TIM3);     GPIO_PinAFConfig(GPIOC, GPIO_PinSource9, GPIO_AF_TIM3);     /* Compute the prescaler value */     PrescalerValue_50 = (uint16_t) ((SystemCoreClock/2 ) / 33335) - 1;     /* Time base configuration */     TIM_TimeBaseStructure.TIM_Period = 665;     TIM_TimeBaseStructure.TIM_Prescaler = PrescalerValue_50;     TIM_TimeBaseStructure.TIM_ClockDivision = 0;     TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;     TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);     /* PWM1 Mode configuration: Channel1 */     TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;     TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; } void TIM_Cong1(uint16_t Dutycycle) {     GPIO_InitTypeDef GPIO_InitStructure;     RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);     RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);     GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;     GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;     GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;     GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;     GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;     GPIO_Init(GPIOC, &GPIO_InitStructure);     /* Connect TIM3 pins to AF2 */       GPIO_PinAFConfig(GPIOC, GPIO_PinSource6, GPIO_AF_TIM3);     PrescalerValue_10 = (uint16_t) ((SystemCoreClock/2 ) / 5000000) - 1;     /* Time base configuration */     TIM_TimeBaseStructure.TIM_Period = 665;     TIM_TimeBaseStructure.TIM_Prescaler = PrescalerValue_10;     TIM_TimeBaseStructure.TIM_ClockDivision = 0;     TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;     TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);     /* PWM1 Mode configuration: Channel1 */     TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;     TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;     TIM_OCInitStructure.TIM_Pulse = Dutycycle;     TIM_OC1Init(TIM3, &TIM_OCInitStructure);     TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);     TIM_ARRPreloadConfig(TIM3, ENABLE);     TIM_Cmd(TIM3, ENABLE);      } void PWM_Generation1(uint16_t Dutycycle) { //    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;     TIM_OCInitStructure.TIM_Pulse = Dutycycle;     TIM_OC4Init(TIM3, &TIM_OCInitStructure);     TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Enable); //    TIM_ARRPreloadConfig(TIM3, ENABLE);     TIM_Cmd(TIM3, ENABLE); } void PWM_Generation2(uint16_t Dutycycle) { //    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;     TIM_OCInitStructure.TIM_Pulse = Dutycycle;     TIM_OC3Init(TIM3, &TIM_OCInitStructure);     TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Enable); //     TIM_ARRPreloadConfig(TIM3, ENABLE);     TIM_Cmd(TIM3, ENABLE); } void PWM_Generation3(uint16_t Dutycycle) { //    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;     TIM_OCInitStructure.TIM_Pulse = Dutycycle;     TIM_OC2Init(TIM3, &TIM_OCInitStructure);     TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable); //    TIM_ARRPreloadConfig(TIM3, ENABLE);     TIM_Cmd(TIM3, ENABLE);     } Regards, Thirukkannan.

[waclawek.jan]

Posted on June 05, 2014 at 15:28

There is only one counter in each timer (and 4 capture-compare units, but they don't count), so you reprogram it to reload at a different rate when you call the other routine.

Review the timer chapter in the user manual, focus on the schematic at the beginning of the chapter. JW

[Tesla DeLorean]

Posted on June 05, 2014 at 17:59

You're going about this all wrong.

Use TWO timers For 50 Hz, set the Prescaler to divide to 1 MHz, ie (SystemCoreClock / 1000000) -1, and the Period to 20000-1 (20 ms 50 Hz), you can then set the Pulse width in 1us units for the 3 channels. For 8 KHz, set the Prescaler to 0, and Period to (SystemCoreClock / 8000) -1 This would be for APB2 based timers, assuming CPU @ 120 MHz, APB2 at 60 MHz, for APB1 at 30 MHz, you'd need to use (SystemCoreClock / 2) for your TIMCLK

[thirukannan]

Posted on June 26, 2014 at 11:56

Hi waclawek.jan,

Thanks for your valuable reply.

[thirukannan]

Posted on June 26, 2014 at 12:01

Hi clive1,

Thanks for your quick and valuable reply. And How your calculating the Prescaler Value and Period based on frequency range.

[Tesla DeLorean]

Posted on June 26, 2014 at 13:41

TIMEBASE = TIMCLK / ((PRESCALER+1) * (PERIOD+1))