STM32F407 Waveform with TIM and DMA

[daded.1]

Hello, 

Hope you're well. I want to create a waveform using a Hardware Timer and DMA. Upon looking at other posts in the forum, it seems the best approach from what I have seen is to use a Timer in Output Compare Mode along with a DMA to transfer the pulse/waveform data from memory to the compare register.

Using a discovery board (STM32-F4), I set up timer 2 channel 3 in output compare mode to toggle and also DMA in circular mode to transfer half-words from memory to peripheral. And I initialized with HAL_TIM_OC_Start_DMA(). However, there is no observed changes on the output pin.

I have set up CubeMX as shown below and attached is the generated code. I appreciate any help setting this up, thank you.

 

/* USER CODE BEGIN Header */
/**
 ******************************************************************************
 * @file : main.c
 * @brief : Main program body
 ******************************************************************************
 * @attention
 *
 * Copyright (c) 2025 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 htim2;
DMA_HandleTypeDef hdma_tim2_up_ch3;

/* USER CODE BEGIN PV */
// | 1000 us | 500us | 1000us | 500us | 500us | 2000us | end of toggle
uint16_t waveBuffer[6] = {1000, 1500, 2500, 3000, 3500, 5500};
/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_DMA_Init(void);
static void MX_TIM2_Init(void);
void MX_USB_HOST_Process(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_DMA_Init();
 MX_TIM2_Init();
 /* USER CODE BEGIN 2 */
HAL_GPIO_WritePin(GPIOD, GPIO_PIN_14, GPIO_PIN_SET);
HAL_TIM_OC_Start_DMA(&htim2, TIM_CHANNEL_3, (uint32_t *)waveBuffer, 6);
 /* USER CODE END 2 */

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

 /* 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_RCC_PWR_CLK_ENABLE();
 __HAL_PWR_VOLTAGESCALING_CONFIG(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 = 8;
 RCC_OscInitStruct.PLL.PLLN = 336;
 RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
 RCC_OscInitStruct.PLL.PLLQ = 7;
 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_DIV4;
 RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;

 if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5) != HAL_OK)
 {
 Error_Handler();
 }
}

/**
 * @brief TIM2 Initialization Function
 * @PAram None
 * @retval None
 */
static void MX_TIM2_Init(void)
{

 /* USER CODE BEGIN TIM2_Init 0 */

 /* USER CODE END TIM2_Init 0 */

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

 /* USER CODE BEGIN TIM2_Init 1 */

 /* USER CODE END TIM2_Init 1 */
 htim2.Instance = TIM2;
 htim2.Init.Prescaler = 84-1;
 htim2.Init.CounterMode = TIM_COUNTERMODE_UP;
 htim2.Init.Period = 22500;
 htim2.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
 htim2.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
 if (HAL_TIM_Base_Init(&htim2) != HAL_OK)
 {
 Error_Handler();
 }
 sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
 if (HAL_TIM_ConfigClockSource(&htim2, &sClockSourceConfig) != HAL_OK)
 {
 Error_Handler();
 }
 if (HAL_TIM_OC_Init(&htim2) != HAL_OK)
 {
 Error_Handler();
 }
 sMasterConfig.MasterOutputTrigger = TIM_TRGO_UPDATE;
 sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
 if (HAL_TIMEx_MasterConfigSynchronization(&htim2, &sMasterConfig) != HAL_OK)
 {
 Error_Handler();
 }
 sConfigOC.OCMode = TIM_OCMODE_TOGGLE;
 sConfigOC.Pulse = 0;
 sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
 sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
 if (HAL_TIM_OC_ConfigChannel(&htim2, &sConfigOC, TIM_CHANNEL_3) != HAL_OK)
 {
 Error_Handler();
 }
 /* USER CODE BEGIN TIM2_Init 2 */

 /* USER CODE END TIM2_Init 2 */
 HAL_TIM_MspPostInit(&htim2);

}

/**
 * Enable DMA controller clock
 */
static void MX_DMA_Init(void)
{

 /* DMA controller clock enable */
 __HAL_RCC_DMA1_CLK_ENABLE();

 /* DMA interrupt init */
 /* DMA1_Stream1_IRQn interrupt configuration */
 HAL_NVIC_SetPriority(DMA1_Stream1_IRQn, 0, 0);
 HAL_NVIC_EnableIRQ(DMA1_Stream1_IRQn);

}

/**
 * @brief GPIO Initialization Function
 * @PAram None
 * @retval None
 */
static void MX_GPIO_Init(void)
{
 GPIO_InitTypeDef GPIO_InitStruct = {0};
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */

 /* GPIO Ports Clock Enable */
 __HAL_RCC_GPIOE_CLK_ENABLE();
 __HAL_RCC_GPIOC_CLK_ENABLE();
 __HAL_RCC_GPIOH_CLK_ENABLE();
 __HAL_RCC_GPIOA_CLK_ENABLE();
 __HAL_RCC_GPIOB_CLK_ENABLE();
 __HAL_RCC_GPIOD_CLK_ENABLE();

 /*Configure GPIO pin Output Level */
 HAL_GPIO_WritePin(CS_I2C_SPI_GPIO_Port, CS_I2C_SPI_Pin, GPIO_PIN_RESET);

 /*Configure GPIO pin Output Level */
 HAL_GPIO_WritePin(OTG_FS_PowerSwitchOn_GPIO_Port, OTG_FS_PowerSwitchOn_Pin, GPIO_PIN_SET);

 /*Configure GPIO pin Output Level */
 HAL_GPIO_WritePin(GPIOD, LD4_Pin|LD3_Pin|LD5_Pin|LD6_Pin
 |Audio_RST_Pin, GPIO_PIN_RESET);

 /*Configure GPIO pin : CS_I2C_SPI_Pin */
 GPIO_InitStruct.Pin = CS_I2C_SPI_Pin;
 GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
 HAL_GPIO_Init(CS_I2C_SPI_GPIO_Port, &GPIO_InitStruct);

 /*Configure GPIO pin : OTG_FS_PowerSwitchOn_Pin */
 GPIO_InitStruct.Pin = OTG_FS_PowerSwitchOn_Pin;
 GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
 HAL_GPIO_Init(OTG_FS_PowerSwitchOn_GPIO_Port, &GPIO_InitStruct);

 /*Configure GPIO pin : PDM_OUT_Pin */
 GPIO_InitStruct.Pin = PDM_OUT_Pin;
 GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
 GPIO_InitStruct.Alternate = GPIO_AF5_SPI2;
 HAL_GPIO_Init(PDM_OUT_GPIO_Port, &GPIO_InitStruct);

 /*Configure GPIO pin : B1_Pin */
 GPIO_InitStruct.Pin = B1_Pin;
 GPIO_InitStruct.Mode = GPIO_MODE_EVT_RISING;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 HAL_GPIO_Init(B1_GPIO_Port, &GPIO_InitStruct);

 /*Configure GPIO pin : BOOT1_Pin */
 GPIO_InitStruct.Pin = BOOT1_Pin;
 GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 HAL_GPIO_Init(BOOT1_GPIO_Port, &GPIO_InitStruct);

 /*Configure GPIO pin : CLK_IN_Pin */
 GPIO_InitStruct.Pin = CLK_IN_Pin;
 GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
 GPIO_InitStruct.Alternate = GPIO_AF5_SPI2;
 HAL_GPIO_Init(CLK_IN_GPIO_Port, &GPIO_InitStruct);

 /*Configure GPIO pins : LD4_Pin LD3_Pin LD5_Pin LD6_Pin
 Audio_RST_Pin */
 GPIO_InitStruct.Pin = LD4_Pin|LD3_Pin|LD5_Pin|LD6_Pin
 |Audio_RST_Pin;
 GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
 HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);

 /*Configure GPIO pin : OTG_FS_OverCurrent_Pin */
 GPIO_InitStruct.Pin = OTG_FS_OverCurrent_Pin;
 GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 HAL_GPIO_Init(OTG_FS_OverCurrent_GPIO_Port, &GPIO_InitStruct);

 /*Configure GPIO pin : MEMS_INT2_Pin */
 GPIO_InitStruct.Pin = MEMS_INT2_Pin;
 GPIO_InitStruct.Mode = GPIO_MODE_EVT_RISING;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 HAL_GPIO_Init(MEMS_INT2_GPIO_Port, &GPIO_InitStruct);

/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}

/* 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\r\n", file, line) */
 /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */

[MasterT]

https://github.com/STMicroelectronics/STM32CubeF4/tree/master/Projects/STM32F429ZI-Nucleo/Examples/TIM/TIM_DMA 

 

[daded.1]

Thank you for the example. I have studied it and I am not sure that I understand the PWM Implementation in this instance, as after reading the reference manual it seems that the duty cycle can be changed but not the period. Perhaps, I should have added more comments in my example but what I am trying to accomplish is similar to a PPM signal. Below is a reference but my application does not need ADC ... thank you!

https://community.st.com/t5/stm32-mcus-products/stm32f100rb-dma-timer-ppm-stream-solved/m-p/432548 

[TDK]

> I want to create a waveform using a Hardware Timer and DMA

Be more specific here. What kind of waveform do you want? What do you want to vary?

[daded.1]

I want to generate a simple wave form that resembles a PPM signal.

| 1000 us | 500us | 1000us | 500us | 500us | 2000us | end of toggle after period is over

Basically, i want to toggle when the timer count has elapsed for each of those values in the array. 

[TDK]

The example provided above can serve as a starting point, except that you should use HAL_TIM_Base_Start_DMA to start the timer instead of HAL_TIM_PWM_Start_DMA. This will update the ARR register with the array values at every cycle. Start the channel prior to this call and set it to toggle the pin on update.