Hi, I need to stop a PWM sometimes and in these cases both the low and the high side Pin should be pulled to low. Is it possible to do that?

[JWelk.1]

I am working with a STM32G474 and I want to use a PWM with 390kHz for a boost converter. I generate a PWM with the HRTIM WaveformOutputStart. Using WaveformOutputStop pulls the LPWM to low, but the HPWM remains on high.

[waclawek.jan]

This is a recurring question with TIM, I don't have experience with HRTIM but one of the most straightforward solutions is to change the respective pins' mode in GPIO_MODER to Out.

JW

[JWelk.1]

Thanks for your answer.

If I start the PWM in the main, it is working fine,. But if after a short delay I change the Pins mode to GPIO Output, the PWM isn't working anymore, although in that part nothing is changed. Any clues what I might be doing wrong?

int main(void)
{
 HAL_Init();
 SystemClock_Config();
 
 /* Initialize all configured peripherals */
 MX_GPIO_Init();
 MX_HRTIM1_Init();
 MX_DMA_Init();
 MX_ADC1_Init();
 
 //PWM Start
 HAL_HRTIM_WaveformOutputStart(&hhrtim1, HRTIM_OUTPUT_TB1 | HRTIM_OUTPUT_TB2 | HRTIM_OUTPUT_TC1 | HRTIM_OUTPUT_TC2 | HRTIM_OUTPUT_TE1 | HRTIM_OUTPUT_TE2);
 HAL_HRTIM_WaveformCounterStart(&hhrtim1, HRTIM_TIMERID_TIMER_B | HRTIM_TIMERID_TIMER_C | HRTIM_TIMERID_TIMER_E);
 
 tein_A1 = (uint32_t)(0.1*14000);
 HRTIM1->sTimerxRegs[HRTIM_TIMERINDEX_TIMER_B].CMP1xR=tein_A1;
 
HAL_Delay(5000);
tein_A1 = (uint32_t)(0.2*14000);
HRTIM1->sTimerxRegs[HRTIM_TIMERINDEX_TIMER_B].CMP1xR=tein_A1;
 
HAL_Delay(5000);
tein_Akku1=0;
if(tein_Akku1==0){
	GPIOA->MODER |= GPIO_MODER_MODER10_0;
	HAL_GPIO_WritePin(GPIOA, GPIO_PIN_10, GPIO_PIN_RESET);
 }
}

[JWelk.1]

I found the Null Duty cycle exception in the reference Manual, but that isn't working either. Does anyone have an example Code where that is working?

[waclawek.jan]

> GPIOA->MODER |= GPIO_MODER_MODER10_0;

If that pin was previously AF (0b01) this puts it into Analog (0b11) instead of Out (0b01).

Also, if you don't have an infinite loop at the end of your program, it will go to .... well that exactly depends on your startup code.

JW

[JWelk.1]

Thanks a lot! It works now and both outputs end up being Low.

If I want to Restart the PWM later, can I just use GPIO_MODER again or do I have to make some additional changes?

[waclawek.jan]

> can I just use GPIO_MODER again

Yes.

The timer keeps running so you might make the change somewhere in the middle of the cycle, be aware of that.

JW