Push Pull PWM

[allanoverst]

Hello ST,

I am having some trouble generating two PWM signals for a push pull converter. 

Ideally I would like the PWM outputs to look like this,

I would like the PWM frequency to be 100kHz and a duty cycle range of 0% to 50%.

I have connected the push pull converter to PA0 and PA1.

First I configure the GPIO Pins,

void MX_PWM_GPIO_Init(void)
{
	GPIO_InitTypeDef GPIO_InitStruct = {0};

	/* Enable clocks */
	__HAL_RCC_TIM2_CLK_ENABLE();
	__HAL_RCC_GPIOA_CLK_ENABLE();

	/* Configure PA0 for TIM2_CH1 */
	GPIO_InitStruct.Pin = GPIO_PIN_0;
	GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
	GPIO_InitStruct.Pull = GPIO_NOPULL;
	GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
	GPIO_InitStruct.Alternate = GPIO_AF2_TIM5; //CH1
	HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

	/* Enable clocks */
	__HAL_RCC_TIM5_CLK_ENABLE();

	/* Configure PA1 for TIM5_CH2
	 * NOTE: Using CH2 on PA1 to avoid conflict with TIM2_CH1 on PA0
	 * You can use different pins if needed
	 */
	GPIO_InitStruct.Pin = GPIO_PIN_1;
	GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
	GPIO_InitStruct.Pull = GPIO_NOPULL;
	GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
	GPIO_InitStruct.Alternate = GPIO_AF1_TIM2; //CH2
	HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

	HAL_Delay(10);
}

 Then I configure TIM2 and TIM5.

//TIM5 -> MASTER CONFIG
//TIM5 CH1 -> PA0
void MX_TIM5_Init_PushPull(void)
{
	TIM_OC_InitTypeDef sConfigOC = {0};
	TIM_MasterConfigTypeDef sMasterConfig = {0};

	/* Timer base configuration */
	htim5.Instance = TIM5;
	htim5.Init.Prescaler = 0;                     // 84 MHz (no prescaling)
	htim5.Init.CounterMode = TIM_COUNTERMODE_UP;
	htim5.Init.Period = 1679;                      // 84 MHz / 840 = 100 kHz
	htim5.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
	htim5.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_ENABLE;

	if (HAL_TIM_PWM_Init(&htim5) != HAL_OK)
	{
		PWM_Error_Handler();
	}

	/* Configure TIM2 as Master (to trigger TIM5) */
	sMasterConfig.MasterOutputTrigger = TIM_TRGO_UPDATE;
	sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_ENABLE;

	if (HAL_TIMEx_MasterConfigSynchronization(&htim5, &sMasterConfig) != HAL_OK)
	{
		PWM_Error_Handler();
	}

	/* PWM Channel 1 configuration - 25% duty cycle */
	sConfigOC.OCMode = TIM_OCMODE_PWM1;
	sConfigOC.Pulse = 420;                        // 25% of 840 = 210
	sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
	sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;

	if (HAL_TIM_PWM_ConfigChannel(&htim5, &sConfigOC, TIM_CHANNEL_1) != HAL_OK)
	{
		PWM_Error_Handler();
	}

	/* Enable output compare preload */
	TIM5->CCMR1 |= TIM_CCMR1_OC1PE;
}

//TIM2 -> SLAVE CONFIG
//TIM2 CH2 -> PA1
void MX_TIM2_Init_PushPull(void)
{
	TIM_OC_InitTypeDef sConfigOC = {0};
	TIM_SlaveConfigTypeDef sSlaveConfig = {0};

	/* Timer base configuration */
	htim2.Instance = TIM2;
	htim2.Init.Prescaler = 0;                     // 84 MHz (no prescaling)
	htim2.Init.CounterMode = TIM_COUNTERMODE_UP;
	htim2.Init.Period = 1679;                      // Same as TIM2 = 100 kHz
	htim2.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
	htim2.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_ENABLE;

	if (HAL_TIM_PWM_Init(&htim2) != HAL_OK)
	{
		PWM_Error_Handler();
	}

	/* PWM Channel 1 configuration - 25% duty cycle */
	sConfigOC.OCMode = TIM_OCMODE_PWM1;
	sConfigOC.Pulse = 420;                        // 25% of 840 = 210
	sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
	sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;

	if (HAL_TIM_PWM_ConfigChannel(&htim2, &sConfigOC, TIM_CHANNEL_2) != HAL_OK)
	{
		PWM_Error_Handler();
	}

	/* Configure TIM5 as Slave (synchronized to TIM2) */
	sSlaveConfig.SlaveMode = TIM_SLAVEMODE_TRIGGER;
	sSlaveConfig.InputTrigger = TIM_TS_ITR2;      // TIM2 is ITR1 for TIM5

	if (HAL_TIM_SlaveConfigSynchronization(&htim2, &sSlaveConfig) != HAL_OK)
	{
		PWM_Error_Handler();
	}

	//Enable output compare preload for CH2 */
	TIM2->CCMR1 |= TIM_CCMR1_OC2PE;
}

Then I tell the timers to start,

void PushPull_Start(void)
{
	//0. Offset TIM2 CH2 - SLAVE.
	__HAL_TIM_SET_COUNTER(&htim2, 420);

	//1. TIM5 CH1 - MASTER
  	HAL_TIM_PWM_Start(&htim5, TIM_CHANNEL_1);
  	//2. TIM2 CH2 - SLAVE
	HAL_TIM_PWM_Start(&htim2, TIM_CHANNEL_2);
}

main() is here,

int main(void)
{
	//Vars
	eMBErrorCode eStatus;

	//0. Initialize HAL
	HAL_Init();
	//1. System Clock Config
	SystemClock_Config();

	MX_UART1_GPIO();
	MX_USART1_UART_Init();

	//2. GPIO Config
	//a. UART
	MX_GPIO_Init();
	HAL_Delay(10);
	//b. PWM
	MX_PWM_GPIO_Init();
	MX_TIM5_Init_PushPull();
	MX_TIM2_Init_PushPull();

	HAL_Delay(10);
	PushPull_Start();

         return 0;
}

The problem I am having is with PA1. I am not getting a signal.

Channel 1 (Yellow) is PA0 and Channel 2 (Green) is PA1.

Does anyone have any suggestions on how to get PA1 working?

Thanks,

Allan

[gbm]

I believe what you need to do is to configure complementary output from a single PWN channel with dead time. You need to use TIMxCHy and TIMxCHyN outputs. TIM1, 8, 15, 16, 17 may be used for that purpose.

[allanoverst]

Hi gbm,

I thought of using TIM1, but the resolution is not high enough for my application. I needed a 32 bit resolution which is why I am using TIM2 and TIM5.

Thanks,

Allan

[TDK]

ARR is preloaded. Generate an update event on each timer after ARR is set and before you start them. Or wait until 2^32 ticks happen (25sec).