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Handzic.Dirk
Handzic.Dirk
Associate III
May 19, 2018
Question

STM32H743 TIM2 input compare

  • May 19, 2018
  • 4 replies
  • 2857 views
Posted on May 19, 2018 at 10:48

Hi,

I can not get the input compare mode working as expected. I need to use TIM2 CH1 as trigger to measure the frequency of external pulses. I have used the methode on a STM32F091 where it works fine.

RCC and GPIO are initialized. And I will get a CC1IF interrupt as soon as I connect the external signal source BUT CCR1 is always 0! It seems to me the counter is not counting. My code to set up the counter:

#define VEL_CLK 10000000       //System is running at 200 MHz PSC is set to 4

TIM2->CCMR1 =  TIM_CCMR1_CC1S_0 ;                                     // ch 1  for input capture   

TIM2->SMCR =      TIM_SMCR_ETP |  TIM_SMCR_SMS_2 |

                                TIM_SMCR_TS_2;                                             // reset mode on ch1

TIM2->CCER = TIM_CCER_CC1P | TIM_CCER_CC1E;

 TIM2->PSC = (APB1_CLK / (VEL_CLK)) - 1;                             // Timer clock

          

 TIM2->CR1 = TIM_CR1_CEN;                                            // Start timer

          

 TIM2->DIER = TIM_DIER_CC1IE;

          

  NVIC_SetPriority(TIM2_IRQn,0);

  NVIC_EnableIRQ(TIM2_IRQn);

The TIM2 registers after intialization (see attached file).

Any suggestions very appreciated!

Best regards

Dirk

This topic has been closed for replies.

4 replies

waclawek.jan
waclawek.jan
Super User
May 19, 2018
Posted on May 19, 2018 at 12:04

If ARR=0, the timer won't count.

If this is the reset value, you should raise complaint at ST, as the RM says otherwise.

JW

Handzic.Dirk
Handzic.DirkAuthor
Associate III
May 19, 2018
Posted on May 19, 2018 at 13:26

Many thanks Jan! You have improved my day a lot! I have struggled with the timer issue since yesterday.

ARR is 0 after reset

ARR is 0 after MX_TIM2_Init

After setting ARR to 0xFFFFFFFF it works as expected

How do I raise a complaint at ST? I have never met so many issues with a ST processor before as with the STM32H743.

Other findings so far apart from TIM2 issue:

Peripherals using PLL2P will not work as DIVP2EN seems to be stuck at 0

Peripherals using PLL3R will not work as DIVR3EN seems to be stuck at 0

Best regards and many thanks

Dirk

Amel NASRI
Amel NASRI
Technical Moderator
May 23, 2018
Posted on May 23, 2018 at 11:59

Hi

Handzic.Dirk

‌,

As suggested by Jan, please create a new thread where you describe the PLLx related issue.

-Amel

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.
henry.dick
henry.dick
Associate II
May 19, 2018
Posted on May 19, 2018 at 17:25

'

I can not get the input compare mode working as expected.'

what is 'input compare'? there is 'input capture' and 'output compare' but what exactly is 'input compare'?

waclawek.jan
waclawek.jan
Super User
May 19, 2018
Posted on May 19, 2018 at 20:07

what exactly is 'input compare'?

:D

Yep, this selective blindness.

How do I raise a complaint at ST?

Here, starting a new thread, clearly stating the case, best accompanied a minimal but complete compilable example exhibiting the problem. Or through the web support form. Or through your FAE.

JW

Amel NASRI
Amel NASRI
Technical Moderator
May 28, 2018
Posted on May 28, 2018 at 16:38

Hi

Handzic.Dirk

‌,

As soon as TIM2 clock is enabled, the ARR value is set to its correct reset value (0xFFFF FFFF). But with the call of 'TIM_Base_SetConfig', it will be set to the defined 'Period' in your code.

-Amel

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.
waclawek.jan
waclawek.jan
Super User
May 28, 2018
Posted on May 28, 2018 at 18:30

Amel,

How do you know Dirk calls TIM_Base_SetConfig()? I see no such indication in his initial post, and in his second post he asserted that

ARR is 0 after reset

Jan

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