STM32F407 Timer does not work

[kyouma001]

Hi I am trying to initialize TIM2 to get a PWM outpt from PA15 of my STM32F407 development board. Here is my TIM init function:

void TIMConfig (void) {
	/*************>>>>>>> STEPS FOLLOWED <<<<<<<<************
	1. Enable the TIM2 clock
	2. Set clock division, enable auto-reload preload
	3. 
	********************************************************/
	
	//	1. Enable the TIM2 clock
	RCC->APB1ENR 	|=	RCC_APB1ENR_TIM2EN;
	
	//	2. Set clock coeff. as 2, enable auto-reload preload
	TIM2->CR1		= 	TIM_CR1_CKD_0 | TIM_CR1_ARPE | TIM_CR1_CMS_0;
	//TIM2->DIER		|= 	TIM_DIER_UIE;
	
	TIM2->CNT		=	0;
	
	TIM2->PSC		=	(uint32_t) 0;
	TIM2->ARR		= 	(uint32_t) 8400;
	
	TIM2->CCR1		= 	(uint32_t) 840;
	TIM2->RCR		= 	(uint32_t) 0;
	
	TIM2->CCMR1		=	TIM_CCMR1_OC1PE | TIM_CCMR1_OC1M_1 | TIM_CCMR1_OC1M_0;	 
	TIM2->CCER		=	TIM_CCER_CC1E | TIM_CCER_CC1P;
	
	TIM2->CR1		|=	TIM_CR1_CEN;
}

And GPIO config function:

void GPIOConfig (void) {
	/*************>>>>>>> STEPS FOLLOWED <<<<<<<<************
	1. Enable the GPIO clock
	2. Set the pin modes
	3. Configure the output mode
	********************************************************/
	
	//	1. Enable the GPIO clock
	RCC->AHB1ENR	|= 	RCC_AHB1ENR_GPIODEN | RCC_AHB1ENR_GPIOAEN;
	
	//	2. Set the pin modes
	//		D13 as output
	GPIOD->MODER	|= 	GPIO_MODER_MODE13_0;
	//		A15 as alternate function
	GPIOA->MODER	|=	GPIO_MODER_MODE15_1;
	GPIOA->AFR[1]	|=	GPIO_AFRH_AFSEL15_0;
	
	//	3. Configure the output mode
	GPIOD->OTYPER	|= 	0;
	GPIOD->OSPEEDR	|= 	0;
}

I call these 2 function in main but I can not see the PWM signal on PA15 pin. What is my fault? Thanks in advance.

[waclawek.jan · Accepted solution]

As you set TIMx_CR1.ARPE, the first cycle until the first update takes the original ARR value, ie. 0xFFFF'FFFF timer clocks.

JW

[S.Ma]

In this example, LED Dimming by PWM. (LEDs.c)

[kyouma001]

Thanks this worked for me.