STM32H743 TIM2 input compare

[Handzic.Dirk]

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

[waclawek.jan]

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]

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

[henry.dick]

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]

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]

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

[Amel NASRI]

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

[waclawek.jan]

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

[Handzic.Dirk]

Posted on May 29, 2018 at 08:07

Hi Amel,

you are right. I checked ARR att the start of main() and it reads 0x00000000, I checked it again after calling MX_TIM2_Init and it is still 0x00000000.

After your reply I have single stepped through the HAL initialization code and indeed after HAl_TIM_Base_MspInit() ARR reads 0xFFFFFFFF and is reset in in the next function TIM_Base_SetConfig() again.

For upcounter mode it does however dont make sense why ARR = 0 would stop the counter from operation.

Dirk

[waclawek.jan]

Posted on May 29, 2018 at 08:15

Corollary: never trust anybody who hints he/she uses Cube. 🙂

Hats off, Amel. The hint was faint and came only in the second post.

For upcounter mode it does however dont make sense why ARR = 0 would stop the counter from operation.

It does: the upcounter counts from 0 to ARR (inclusive), so here the counter counts from 0 to 0 (so does not change at all).

JW