How change the PWM polarity of CH2N during runtime ?

[ForgottenTale]

I have set Timer 8 to PWM Generation CH2 CH2N. Based on the value read by the ADC, I want to change the polarity of both CH2 and CH2N. I have found that using

__HAL_TIM_SET_CAPTUREPOLARITY

, I could change the polarity of CH2 but the polarity of CH1N remains the same as shown in the image. So how could I change the polarity of both CH2 CH2N ?

[KnarfB]

__HAL_TIM_SET_CAPTUREPOLARITY is for input capture, but not for output compare which does the PWM output here. You may switch from PWM mode 1 to PWM mode 2.

hth

KnarfB

[ForgottenTale]

Which HAL function will do that during runtime ?

[waclawek.jan]

> __HAL_TIM_SET_CAPTUREPOLARITY is for input capture, but not for output compare which does the PWM output here.

It's the same bit, TIMx_CCER.CCxP, even if maybe Cube/HAL has different incantations for it.

The CCxN channel's polarity is similarly controlled by TIMx_CCER.CCxNP. You can try to find some Cube/HAL macro for that if you want, Cube is open source.

Output Compare mode is determined by TIMx_CCMRx.OCxM field, simply change that field for different mode.

Read the TIM chapter in RM.

JW

[ForgottenTale]

How do I write the code for it? I am new to programming this type of board. I have only experience in programming Arduino

[waclawek.jan]

TIM8->CCER |= TIM_CCER_CC2NE [EDIT] see post below [/EDIT]

I started to write you a longer answer, but then it turned into this.

JW

[ForgottenTale]

This doesn't seem to work. The PWM isn't getting inverted

[waclawek.jan]

Ufff.... sorry.... CCxNE is the Enable bit for the TIMx_CHxN channel. Polarity is swapped using the CCxNP bit:

TIM8->CCER |= TIM_CCER_CC2NP;

JW

[ForgottenTale]

PWM channel of CH2N got inverted, but it didn't work for CH2. Also, I need toggle between non-inverted and inverted PWM based on the value read from the ADC. How can i do that ?

I don't know if the code given below is the correct way to toggle between PWM mode. But it is definitely working.

 void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef* hadc)
{
  value =  HAL_ADC_GetValue(&hadc1);
  voltage = ReadDCVoltage25(value);
 
	if(voltage>50){
	__HAL_TIM_SET_CAPTUREPOLARITY(&htim1,TIM_CHANNEL_2,TIM_INPUTCHANNELPOLARITY_FALLING);
	TIM1->CCER  |= TIM_CCER_CC2NP ;
		
	}
	else if(voltage<50){
	__HAL_TIM_SET_CAPTUREPOLARITY(&htim1,TIM_CHANNEL_2,TIM_INPUTCHANNELPOLARITY_RISING);
	}
}

[waclawek.jan]

> PWM channel of CH2N got inverted, but it didn't work for CH2.

As I said like 3 posts ago, it's CCxP for the TIMx_CHx and CCxNP for TIMx_CHxN.

TIM8->CCER |= TIM_CCER_CC2P;

Have you read the TIM chapter in RM? And within it, the CCER register description?

Have you experimented with the TIM registers in the debugger?

JW