How to use HAL DMA to generate PWM on P-NUCLEO-WB?

Forum|Forum|4 years ago
February 8, 2022
7 replies
5770 views

I am trying to generate PWM by using DMA with HAL library:

uint16_t buffer[1] = {1500};
... 
Status = HAL_TIM_PWM_Start_DMA(&htim2, TIM_CHANNEL_1, (uint32_t *)buffer, 1);

however nothing happens. I am able to generate PWM without DMA:

 TIM2->CCR1 = 500;
 HAL_TIM_PWM_Start(&htim2, TIM_CHANNEL_1);

Is there any example of DMA PWM usage?

Remy ISSALYS

Technical Moderator

Hello,

Maybe you have a wrong configuration for your DMA, according to your code you need to set DMA for TIM2 channel 1 and to configure Memory to Peripheral direction if you need to send data to the peripheral.

Best Regards

LZure.1Author

Associate

I have followed this tutorial without success:

https://controllerstech.com/pwm-with-dma-in-stm32/

Please take a look at my code:

TIM init:

/**
 * @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 = 64-1;
 htim2.Init.CounterMode = TIM_COUNTERMODE_UP;
 htim2.Init.Period = 10000-1;
 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_PWM_Init(&htim2) != HAL_OK)
 {
 Error_Handler();
 }
 sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
 sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
 if (HAL_TIMEx_MasterConfigSynchronization(&htim2, &sMasterConfig) != HAL_OK)
 {
 Error_Handler();
 }
 sConfigOC.OCMode = TIM_OCMODE_PWM1;
 sConfigOC.Pulse = 0;
 sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
 sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
 if (HAL_TIM_PWM_ConfigChannel(&htim2, &sConfigOC, TIM_CHANNEL_1) != HAL_OK)
 {
 Error_Handler();
 }
 /* USER CODE BEGIN TIM2_Init 2 */
 
 /* USER CODE END TIM2_Init 2 */
 HAL_TIM_MspPostInit(&htim2);
 
}

TIM_Base_MspInit:

void HAL_TIM_Base_MspInit(TIM_HandleTypeDef* htim_base)
{
 if(htim_base->Instance==TIM2)
 {
 /* USER CODE BEGIN TIM2_MspInit 0 */
 
 /* USER CODE END TIM2_MspInit 0 */
 /* Peripheral clock enable */
 __HAL_RCC_TIM2_CLK_ENABLE();
 
 /* TIM2 DMA Init */
 /* TIM2_CH1 Init */
 hdma_tim2_ch1.Instance = DMA1_Channel1;
 hdma_tim2_ch1.Init.Request = DMA_REQUEST_TIM2_CH1;
 hdma_tim2_ch1.Init.Direction = DMA_MEMORY_TO_PERIPH;
 hdma_tim2_ch1.Init.PeriphInc = DMA_PINC_DISABLE;
 hdma_tim2_ch1.Init.MemInc = DMA_MINC_ENABLE;
 hdma_tim2_ch1.Init.PeriphDataAlignment = DMA_PDATAALIGN_HALFWORD;
 hdma_tim2_ch1.Init.MemDataAlignment = DMA_MDATAALIGN_HALFWORD;
 hdma_tim2_ch1.Init.Mode = DMA_NORMAL;
 hdma_tim2_ch1.Init.Priority = DMA_PRIORITY_LOW;
 if (HAL_DMA_Init(&hdma_tim2_ch1) != HAL_OK)
 {
 Error_Handler();
 }
 
 __HAL_LINKDMA(htim_base,hdma[TIM_DMA_ID_CC1],hdma_tim2_ch1);
 
 /* USER CODE BEGIN TIM2_MspInit 1 */
 
 /* USER CODE END TIM2_MspInit 1 */
 }
 
}

TIM MspPostInit:

void HAL_TIM_MspPostInit(TIM_HandleTypeDef* htim)
{
 GPIO_InitTypeDef GPIO_InitStruct = {0};
 if(htim->Instance==TIM2)
 {
 /* USER CODE BEGIN TIM2_MspPostInit 0 */
 
 /* USER CODE END TIM2_MspPostInit 0 */
 
 __HAL_RCC_GPIOA_CLK_ENABLE();
 /**TIM2 GPIO Configuration
 PA0 ------> 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_LOW;
 GPIO_InitStruct.Alternate = GPIO_AF1_TIM2;
 HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
 
 /* USER CODE BEGIN TIM2_MspPostInit 1 */
 
 /* USER CODE END TIM2_MspPostInit 1 */
 }
 
}

DMA init:

static void MX_DMA_Init(void)
{
 
 /* DMA controller clock enable */
 __HAL_RCC_DMAMUX1_CLK_ENABLE();
 __HAL_RCC_DMA1_CLK_ENABLE();
 
 /* DMA interrupt init */
 /* DMA1_Channel1_IRQn interrupt configuration */
 HAL_NVIC_SetPriority(DMA1_Channel1_IRQn, 0, 0);
 HAL_NVIC_EnableIRQ(DMA1_Channel1_IRQn);
 
}

Code to generate PWM:

int datasentflag=0;
 
void HAL_TIM_PWM_PulseFinishedCallback(TIM_HandleTypeDef *htim)
{
 HAL_TIM_PWM_Stop_DMA(htim, TIM_CHANNEL_1);
 datasentflag = 1;
}
 
uint16_t pwmData[24];
 
void WS2812_Send (uint32_t color)
{
 for (int i=23; i>=0; i--)
 {
 if (color&(1<<i))
 {
 pwmData[i] = 6600;
 }
 else pwmData[i] = 3300;
 }
 
 HAL_TIM_PWM_Start_DMA(&htim2, TIM_CHANNEL_1, (uint32_t *)pwmData, 24);
 while (!datasentflag){};
 datasentflag = 0;
}

Main:

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();
 
/* Configure the peripherals common clocks */
 PeriphCommonClock_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 */
 uint32_t colour = 0x347235; // colour code for some color
 WS2812_Send(colour);
 
 
 while (1)
 {
 
 }
 
 /* USER CODE END 2 */
 
 /* Infinite loop */
 /* USER CODE BEGIN WHILE */
 
 /* USER CODE END 3 */
}

and this is result on pin PA0 (TIM2_Ch1):

Is there anythin I am missing or is this FW issue?