How to configure GPIO output for a given timer?

[Tommino]

Hello,

I have a very straightforward question but I am not able to find the answer in the user manual. I am using the L476RG nucleo board and setting the TIM5 registers to output a PWM. How can I select the output pin? Is it fixed or does it have some degree of freedom?

This is what I have write so far.

Thanks in advance.

void TIM5Init (void){
	 // Enable the timer clock
	 RCC->APB1ENR1 |= (1<<3); // Enable the tim5 clock writing 1 in bit 3
	 // Set the prescaler and the ARR
	 TIM5 -> PSC = 79; // 80 MHz/80= 1MHz clock --> 1us count
	 TIM5-> ARR = PWMf; // ARR value --> set the frequency: total counts before starting again the timer
	 // set the PWM mode
	 TIM5 -> CCMR1 |= (0<<0); // to set the output compare mode
	 TIM5 -> CCMR1 |= (1<<3); // OC1PE bit to enable the preload register
	 TIM5 -> CCMR1 |= (6<<4); // OC1M bits to set the PWM mode
	 TIM5 -> CR1 |= (1<<7); // ARPE BIT:ARR register is buffered
	 TIM5-> EGR |= (0<<0); // UG bit 
	 TIM5 -> CCER |= (0<<1); // CC1P bits to set the polarity (write 0 in bit 1 to have active high)
	 TIM5-> CCER |= (1<<0); // output on the corresponding output pin enable ?????????
	 // set the duty cycle
	 TIM5->CCR1 = 10000; // 
}

[SofLit]

Hello,

The datasheet provides this information, especially tables 16 and 17:

So you need to select the right GPIO alternate function to have PWM of TIM5 available on a GPIO pin.

In your case You need to configure AF2 as shown in the table above.

You can refer to the example provided in STM32CubeL4 under the path Projects\STM32L476G_EVAL\Examples\TIM\TIM_PWMOutput : especially the file stm32l4xx_hal_msp.c in which GPIO pin of PWM output is configured.