STM32G4 Use complementary PWM output without using the original PWM output

Question

MCU: STM32G491RET6 Due to other pins being unavailable, I am trying to use TIM8_CH3N to generate a PWM output. To test this, I used CubeMx to generate configuration code for me, and only added the line to start PWM:HAL_TIM_PWM_Start(&htim8, TIM_CHANNEL_3); // start pwm generationTo check that the MCU and CubeMx code are good, I also am generating another PWM, on TIM3_CH1. Again, I only added one line to the CubeMx generated code: HAL_TIM_PWM_Start(&htim3, TIM_CHANNEL_1); // start pwm generation TIM3_CH1 PWM works, while TIM8_CH3N does not. I am not sure if it is possible to use only TIM8_CH3N, without using TIM8_CH3 (I can't use TIM8_CH3 because the pin it is connected to has another dedicated function).Any help appreciated.Code: main.c:  main.c:

/* USER CODE BEGIN Header */
/**
******************************************************************************
* @file : main.c
* @brief : Main program body
******************************************************************************
* @attention
*
* Copyright (c) 2023 STMicroelectronics.
* All rights reserved.
*
* This software is licensed under terms that can be found in the LICENSE file
* in the root directory of this software component.
* If no LICENSE file comes with this software, it is provided AS-IS.
*
******************************************************************************
*/
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */

/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */

/* USER CODE END PTD */

/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
/* USER CODE END PD */

/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */

/* USER CODE END PM */

/* Private variables ---------------------------------------------------------*/
TIM_HandleTypeDef htim3;
TIM_HandleTypeDef htim8;

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_TIM8_Init(void);
static void MX_TIM3_Init(void);
/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */

/* USER CODE END 0 */

/**
* @brief The application entry point.
* @retval int
*/
int main(void)
{
/* USER CODE BEGIN 1 */

/* USER CODE END 1 */

/* MCU Configuration--------------------------------------------------------*/

/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();

/* USER CODE BEGIN Init */

/* USER CODE END Init */

/* Configure the system clock */
SystemClock_Config();

/* USER CODE BEGIN SysInit */

/* USER CODE END SysInit */

/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_TIM8_Init();
MX_TIM3_Init();
/* USER CODE BEGIN 2 */

/* USER CODE END 2 */

/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
/* USER CODE END WHILE */

/* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */
}

/**
* @brief System Clock Configuration
* @retval None
*/
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

/** Configure the main internal regulator output voltage
*/
HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1);

/** Initializes the RCC Oscillators according to the specified parameters
* in the RCC_OscInitTypeDef structure.
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = RCC_PLLM_DIV1;
RCC_OscInitStruct.PLL.PLLN = 16;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
RCC_OscInitStruct.PLL.PLLQ = RCC_PLLQ_DIV2;
RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV2;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}

/** Initializes the CPU, AHB and APB buses clocks
*/
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
{
Error_Handler();
}
}

/**
* @brief TIM3 Initialization Function
* @PAram None
* @retval None
*/
static void MX_TIM3_Init(void)
{

/* USER CODE BEGIN TIM3_Init 0 */

/* USER CODE END TIM3_Init 0 */

TIM_MasterConfigTypeDef sMasterConfig = {0};
TIM_OC_InitTypeDef sConfigOC = {0};

/* USER CODE BEGIN TIM3_Init 1 */

/* USER CODE END TIM3_Init 1 */
htim3.Instance = TIM3;
htim3.Init.Prescaler = 64-1;
htim3.Init.CounterMode = TIM_COUNTERMODE_UP;
htim3.Init.Period = 40-1;
htim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
htim3.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
if (HAL_TIM_PWM_Init(&htim3) != HAL_OK)
{
Error_Handler();
}
sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
if (HAL_TIMEx_MasterConfigSynchronization(&htim3, &sMasterConfig) != HAL_OK)
{
Error_Handler();
}
sConfigOC.OCMode = TIM_OCMODE_PWM1;
sConfigOC.Pulse = 30;
sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
if (HAL_TIM_PWM_ConfigChannel(&htim3, &sConfigOC, TIM_CHANNEL_1) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN TIM3_Init 2 */
HAL_TIM_PWM_Start(&htim3, TIM_CHANNEL_1); // start pwm generation

/* USER CODE END TIM3_Init 2 */
HAL_TIM_MspPostInit(&htim3);

}

/**
* @brief TIM8 Initialization Function
* @PAram None
* @retval None
*/
static void MX_TIM8_Init(void)
{

/* USER CODE BEGIN TIM8_Init 0 */

/* USER CODE END TIM8_Init 0 */

TIM_MasterConfigTypeDef sMasterConfig = {0};
TIM_OC_InitTypeDef sConfigOC = {0};
TIM_BreakDeadTimeConfigTypeDef sBreakDeadTimeConfig = {0};

/* USER CODE BEGIN TIM8_Init 1 */

/* USER CODE END TIM8_Init 1 */
htim8.Instance = TIM8;
htim8.Init.Prescaler = 64-1;
htim8.Init.CounterMode = TIM_COUNTERMODE_UP;
htim8.Init.Period = 40-1;
htim8.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
htim8.Init.RepetitionCounter = 0;
htim8.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
if (HAL_TIM_PWM_Init(&htim8) != HAL_OK)
{
Error_Handler();
}
sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
sMasterConfig.MasterOutputTrigger2 = TIM_TRGO2_RESET;
sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
if (HAL_TIMEx_MasterConfigSynchronization(&htim8, &sMasterConfig) != HAL_OK)
{
Error_Handler();
}
sConfigOC.OCMode = TIM_OCMODE_PWM1;
sConfigOC.Pulse = 30;
sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
sConfigOC.OCNPolarity = TIM_OCNPOLARITY_HIGH;
sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
sConfigOC.OCIdleState = TIM_OCIDLESTATE_RESET;
sConfigOC.OCNIdleState = TIM_OCNIDLESTATE_RESET;
if (HAL_TIM_PWM_ConfigChannel(&htim8, &sConfigOC, TIM_CHANNEL_3) != HAL_OK)
{
Error_Handler();
}
sBreakDeadTimeConfig.OffStateRunMode = TIM_OSSR_DISABLE;
sBreakDeadTimeConfig.OffStateIDLEMode = TIM_OSSI_DISABLE;
sBreakDeadTimeConfig.LockLevel = TIM_LOCKLEVEL_OFF;
sBreakDeadTimeConfig.DeadTime = 0;
sBreakDeadTimeConfig.BreakState = TIM_BREAK_DISABLE;
sBreakDeadTimeConfig.BreakPolarity = TIM_BREAKPOLARITY_HIGH;
sBreakDeadTimeConfig.BreakFilter = 0;
sBreakDeadTimeConfig.BreakAFMode = TIM_BREAK_AFMODE_INPUT;
sBreakDeadTimeConfig.Break2State = TIM_BREAK2_DISABLE;
sBreakDeadTimeConfig.Break2Polarity = TIM_BREAK2POLARITY_HIGH;
sBreakDeadTimeConfig.Break2Filter = 0;
sBreakDeadTimeConfig.Break2AFMode = TIM_BREAK_AFMODE_INPUT;
sBreakDeadTimeConfig.AutomaticOutput = TIM_AUTOMATICOUTPUT_DISABLE;
if (HAL_TIMEx_ConfigBreakDeadTime(&htim8, &sBreakDeadTimeConfig) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN TIM8_Init 2 */
HAL_TIM_PWM_Start(&htim8, TIM_CHANNEL_3); // start pwm generation

/* USER CODE END TIM8_Init 2 */
HAL_TIM_MspPostInit(&htim8);

}

/**
* @brief GPIO Initialization Function
* @PAram None
* @retval None
*/
static void MX_GPIO_Init(void)
{

/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOF_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
__HAL_RCC_GPIOB_CLK_ENABLE();

}

/* USER CODE BEGIN 4 */

/* USER CODE END 4 */

/**
* @brief This function is executed in case of error occurrence.
* @retval None
*/
void Error_Handler(void)
{
/* USER CODE BEGIN Error_Handler_Debug */
/* User can add his own implementation to report the HAL error return state */
__disable_irq();
while (1)
{
}
/* USER CODE END Error_Handler_Debug */
}

#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @PAram file: pointer to the source file name
* @PAram line: assert_param error line source number
* @retval None
*/
void assert_failed(uint8_t *file, uint32_t line)
{
/* USER CODE BEGIN 6 */
/* User can add his own implementation to report the file name and line number,
ex: printf("Wrong parameters value: file %s on line %d
", file, line) */
/* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */

stm32g4xx_hal_msp.c:  /* USER CODE BEGIN Header */
/**
******************************************************************************
* @file stm32g4xx_hal_msp.c
* @brief This file provides code for the MSP Initialization
* and de-Initialization codes.
******************************************************************************
* @attention
*
* Copyright (c) 2023 STMicroelectronics.
* All rights reserved.
*
* This software is licensed under terms that can be found in the LICENSE file
* in the root directory of this software component.
* If no LICENSE file comes with this software, it is provided AS-IS.
*
******************************************************************************
*/
/* USER CODE END Header */

/* Includes ------------------------------------------------------------------*/
#include "main.h"
/* USER CODE BEGIN Includes */

/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN TD */

/* USER CODE END TD */

/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN Define */

/* USER CODE END Define */

/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN Macro */

/* USER CODE END Macro */

/* Private variables ---------------------------------------------------------*/
/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* External functions --------------------------------------------------------*/
/* USER CODE BEGIN ExternalFunctions */

/* USER CODE END ExternalFunctions */

/* USER CODE BEGIN 0 */

/* USER CODE END 0 */

void HAL_TIM_MspPostInit(TIM_HandleTypeDef *htim);
/**
* Initializes the Global MSP.
*/
void HAL_MspInit(void)
{
/* USER CODE BEGIN MspInit 0 */

/* USER CODE END MspInit 0 */

__HAL_RCC_SYSCFG_CLK_ENABLE();
__HAL_RCC_PWR_CLK_ENABLE();

/* System interrupt init*/

/** Disable the internal Pull-Up in Dead Battery pins of UCPD peripheral
*/
HAL_PWREx_DisableUCPDDeadBattery();

/* USER CODE BEGIN MspInit 1 */

/* USER CODE END MspInit 1 */
}

/**
* @brief TIM_PWM MSP Initialization
* This function configures the hardware resources used in this example
* @PAram htim_pwm: TIM_PWM handle pointer
* @retval None
*/
void HAL_TIM_PWM_MspInit(TIM_HandleTypeDef* htim_pwm)
{
if(htim_pwm->Instance==TIM3)
{
/* USER CODE BEGIN TIM3_MspInit 0 */

/* USER CODE END TIM3_MspInit 0 */
/* Peripheral clock enable */
__HAL_RCC_TIM3_CLK_ENABLE();
/* USER CODE BEGIN TIM3_MspInit 1 */

/* USER CODE END TIM3_MspInit 1 */
}
else if(htim_pwm->Instance==TIM8)
{
/* USER CODE BEGIN TIM8_MspInit 0 */

/* USER CODE END TIM8_MspInit 0 */
/* Peripheral clock enable */
__HAL_RCC_TIM8_CLK_ENABLE();
/* USER CODE BEGIN TIM8_MspInit 1 */

/* USER CODE END TIM8_MspInit 1 */
}

}

void HAL_TIM_MspPostInit(TIM_HandleTypeDef* htim)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
if(htim->Instance==TIM3)
{
/* USER CODE BEGIN TIM3_MspPostInit 0 */

/* USER CODE END TIM3_MspPostInit 0 */
__HAL_RCC_GPIOA_CLK_ENABLE();
/**TIM3 GPIO Configuration
PA6 ------> TIM3_CH1
*/
GPIO_InitStruct.Pin = GPIO_PIN_6;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
GPIO_InitStruct.Alternate = GPIO_AF2_TIM3;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

/* USER CODE BEGIN TIM3_MspPostInit 1 */

/* USER CODE END TIM3_MspPostInit 1 */
}
else if(htim->Instance==TIM8)
{
/* USER CODE BEGIN TIM8_MspPostInit 0 */

/* USER CODE END TIM8_MspPostInit 0 */

__HAL_RCC_GPIOB_CLK_ENABLE();
/**TIM8 GPIO Configuration
PB1 ------> TIM8_CH3N
*/
GPIO_InitStruct.Pin = GPIO_PIN_1;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
GPIO_InitStruct.Alternate = GPIO_AF4_TIM8;
HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

/* USER CODE BEGIN TIM8_MspPostInit 1 */

/* USER CODE END TIM8_MspPostInit 1 */
}

}
/**
* @brief TIM_PWM MSP De-Initialization
* This function freeze the hardware resources used in this example
* @PAram htim_pwm: TIM_PWM handle pointer
* @retval None
*/
void HAL_TIM_PWM_MspDeInit(TIM_HandleTypeDef* htim_pwm)
{
if(htim_pwm->Instance==TIM3)
{
/* USER CODE BEGIN TIM3_MspDeInit 0 */

/* USER CODE END TIM3_MspDeInit 0 */
/* Peripheral clock disable */
__HAL_RCC_TIM3_CLK_DISABLE();
/* USER CODE BEGIN TIM3_MspDeInit 1 */

/* USER CODE END TIM3_MspDeInit 1 */
}
else if(htim_pwm->Instance==TIM8)
{
/* USER CODE BEGIN TIM8_MspDeInit 0 */

/* USER CODE END TIM8_MspDeInit 0 */
/* Peripheral clock disable */
__HAL_RCC_TIM8_CLK_DISABLE();
/* USER CODE BEGIN TIM8_MspDeInit 1 */

/* USER CODE END TIM8_MspDeInit 1 */
}

}

/* USER CODE BEGIN 1 */

/* USER CODE END 1 */

TDK · Accepted Answer

The complementary signal output needs to be enabled separately with a different function:

HAL_TIMEx_PWMN_Start(&htim8, TIM_CHANNEL_3);

It is possible to use CH3N output without using CH3 output. The channel still runs, but if you don't assign the CH3 pin the timer AF, it won't be connected to the timer.

Sarra.S · Answer

Hello @DRad, For advanced timers, you need to set the main output bit (TIM_BDTR.MOE ) to enable the output

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