Timer issue

kalhana · ‎2016-02-08

Posted on February 08, 2016 at 17:03

Hi,

I'm having an issue setting up TIM1 for PWM on the STM32F446.

In the following code, the PWM works for TIM2 but not for TIM1.

Any ideas?

Thank you.

RCC->APB1ENR |= (1UL << 0); // TIM2 clock enable

TIM2->PSC = 89; // set prescaler = 1 MHz

TIM2->ARR = 999; // set auto-reload = for 1 kHz

TIM2->CCR2 = 15; // 1.5% duty cycle

TIM2->CCMR1 |= 0x6800;

TIM2->CR1 |= 0x80;

TIM2->CCER |= 0x10;

TIM2->EGR |= 0x01;

TIM2->CR1 |= 0x01;

RCC->AHB1ENR |= (1UL << 0); // GPIOA clock enable

GPIOA->MODER |= (2UL << 2*1); // PA1 - is alt function

GPIOA->OSPEEDR |= (3UL << 2*1); // PA1 - is high speed

GPIOA->AFR[0] |= (1 << 4); // PA1 - AF1 mapping

//================================================================

RCC->APB2ENR |= (1UL << 0); // TIM1 clock enable

TIM1->PSC = 179; // set prescaler = 1 MHz

TIM1->ARR = 999; // set auto-reload = for 1 kHz

TIM1->CCR2 = 15; // 1.5% duty cycle

TIM1->CCMR1 |= 0x6800;

TIM1->CR1 |= 0x80;

TIM1->CCER |= 0x10;

TIM1->EGR |= 0x01;

TIM1->CR1 |= 0x01;

RCC->AHB1ENR |= (1UL << 0); // GPIOA clock enable

GPIOA->MODER |= (2UL << 2*9); // PA9 - is alt function

GPIOA->OSPEEDR |= (3UL << 2*9); // PA9 - is high speed

GPIOA->AFR[1] |= (1 << 4); // PA9 - AF1 mapping

waclawek.jan · ‎2016-02-08

Posted on February 08, 2016 at 17:11

Ah, the classical TIM1/TIM8 gotcha #1.

Set TIMx_BDTR.MOE.

JW

Radosław · ‎2016-02-08

Posted on February 08, 2016 at 17:32

Do you love magic numbers? Why?

This code is not readable.

kalhana · ‎2016-02-08

Posted on February 08, 2016 at 17:44

Thank you, that was the issue, now working.

Well I started using STM32 back in 2009 when there was no HAL/CMIS stuff as far as I know. And I prefer setting values directly to registers (Although I do usually set #defines and is a bit better than this code I posted which was done in a hurry to see if it works).

I really don't like HAL code where it has to run though so many lines of code (and jump through functions) just to set the value for 1 register (it is actually very hard to follow never mind the penalty in CPU time). Also, I never use STM's Init functions that you need to pass Init structures to, I like more control over what I'm doing.

Radosław · ‎2016-02-08

Posted on February 08, 2016 at 17:52

Use CMSIS vendor file for bits definition.