I want to generate a PWM signal using DMA TIMER, in which the duty cylce should change in very frequently. Till 10 times the Duty Cycle changes with out any issues after which when I increase the array size the waveform is getting not correct. Kindly help

[JohnsAby]

DMA config as below

 hdma_tim.Instance = TIMx_CC1_DMA_INST;
 
 hdma_tim.Init.Channel = DMA_CHANNEL_6;
 
 hdma_tim.Init.Direction = DMA_MEMORY_TO_PERIPH;
 
 hdma_tim.Init.PeriphInc = DMA_PINC_DISABLE;
 
 hdma_tim.Init.MemInc = DMA_MINC_ENABLE;
 
 hdma_tim.Init.PeriphDataAlignment = DMA_PDATAALIGN_WORD;
 
 hdma_tim.Init.MemDataAlignment = DMA_MDATAALIGN_WORD;
 
 hdma_tim.Init.Mode = DMA_CIRCULAR;
 
 hdma_tim.Init.Priority = DMA_PRIORITY_HIGH;
 
 hdma_tim.Init.FIFOMode = DMA_FIFOMODE_DISABLE;
 
 hdma_tim.Init.FIFOThreshold = DMA_FIFO_THRESHOLD_FULL;
 
 hdma_tim.Init.MemBurst = DMA_MBURST_SINGLE;
 
 hdma_tim.Init.PeriphBurst = DMA_PBURST_SINGLE;
 
  
 
 HAL_DMA_Init(&hdma_tim);
 
 
 
 /* Link hdma_tim to hdma[TIM_DMA_ID_CC1] (channel1) */
 
 __HAL_LINKDMA(&TIMx_handle, hdma[TIM_DMA_ID_CC1], hdma_tim);
 
 
 
 /*##-2- Configure the NVIC for DMA #########################################*/
 
 /* NVIC configuration for DMA transfer complete interrupt */
 
 HAL_NVIC_SetPriority(TIMx_DMA_IRQn, 2, 4);
 
 HAL_NVIC_EnableIRQ(TIMx_DMA_IRQn);

PWM generation code +++++++++++++++++++++++++++++++

 TIMx_handle.Init.Period = 50;
 
 TIMx_handle.Init.RepetitionCounter = 0;
 
 TIMx_handle.Init.Prescaler = 0;
 
 TIMx_handle.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
 
 TIMx_handle.Init.CounterMode = TIM_COUNTERMODE_UP;
 
  
 
 
 
 /*##-1- Initialize the timer in time base generation mode ##################*/
 
 HAL_TIM_PWM_Init(&TIMx_handle);
 
 
 
 /*##-2- Configure the PWM channels #########################################*/
 
 /* Common configuration */
 
 TIMx_sConfig.OCMode    = TIM_OCMODE_PWM1;
 
 TIMx_sConfig.OCPolarity  = TIM_OCPOLARITY_HIGH;
 
 TIMx_sConfig.Pulse    = 5;//aCCValue_Buffer[0];
 
 TIMx_sConfig.OCNPolarity = TIM_OCNPOLARITY_HIGH;
 
 TIMx_sConfig.OCFastMode  = TIM_OCFAST_DISABLE;
 
 TIMx_sConfig.OCIdleState = TIM_OCIDLESTATE_RESET;
 
 TIMx_sConfig.OCNIdleState = TIM_OCNIDLESTATE_RESET;
 
  
 
 HAL_TIM_PWM_ConfigChannel(&TIMx_handle, &TIMx_sConfig, TIM_CHANNEL_1);
 
  
 
 /*##-3- Start PWM signals generation #######################################*/
 
 
 
HAL_TIM_PWM_Start_DMA(&TIMx_handle, TIM_CHANNEL_1, aCCValue_Buffer, SIZEARRAY);

 uint32_t aCCValue_Buffer[SIZEARRAY] = {0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48};

where SIZEARRAY is 25

Below image is for array size 10, came as expected

 Below image is for array size 25, not good (I should see 25 different DCs)

[waclawek.jan]

Which STM32?

Read out and check/compare content of DMA (and perhaps also TIM) registers for both cases.

JW

[JohnsAby]

Hi JW

Thanks for update

Am using STM32F427.

I want to update DutyCycle of a PWM timer at every 2us, so I made an array of 25 values and called

HAL_TIM_PWM_Start_DMA(&TIMx_handle, TIM_CHANNEL_1, aCCValue_Buffer, SIZEARRAY);

I have configurated DMA in circular mode.

According to my understanding I should get the below call back after full array gets updated.

void HAL_TIM_PWM_PulseFinishedCallback(TIM_HandleTypeDef *htim)
{
	HAL_TIM_PWM_Stop_DMA(&TIMx_handle, TIM_CHANNEL_1);
}

But this is not the case, each DU change this is getting called, is there any callback I get after full buffer is empty ?

Please help

[waclawek.jan]

> But this is not the case, each DU change this is getting called, is there any callback I get after full buffer is empty ?

I don't know, I don't use Cube.

Normally, interrupts from timer and from DMA have separate vectors, it's Cube which mingles them together.

JW