DMA for Quadtrature Encoder not working (stm32g0x1)

[shadj]

I am working with a Quadrature Encoder that uses TIM2 (encoder mode). The encoder mode automatically captures an increase in the register htim2.Instance->CNT

I am trying to use DMA to fill a buffer with the CNT values however it does not seem to work. 

I would really appreciate any help!

My relevant code: 

initializations: 
 TIM_HandleTypeDef htim2;
 TIM_HandleTypeDef htim3;
 TIM_HandleTypeDef htim16;
 DMA_HandleTypeDef hdma_tim16_com;

 int32_t count_buf[COUNT_BUF_CAPACITY];

main: 

  MX_DMA_Init();
  MX_TIM2_Init();
  MX_TIM16_Init();

  HAL_TIM_Base_Start_IT(&htim16);
  HAL_TIM_Encoder_Start_IT(&htim2, TIM_CHANNEL_ALL);

  HAL_DMA_Start(&hdma_tim16_com,&htim2.Instance->CNT,count_buf,4);


static void MX_DMA_Init(void)
{

  /* DMA controller clock enable */
  __HAL_RCC_DMA2_CLK_ENABLE();

  /* DMA interrupt init */
  /* DMA1_Ch4_7_DMA2_Ch1_5_DMAMUX1_OVR_IRQn interrupt configuration */
  HAL_NVIC_SetPriority(DMA1_Ch4_7_DMA2_Ch1_5_DMAMUX1_OVR_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(DMA1_Ch4_7_DMA2_Ch1_5_DMAMUX1_OVR_IRQn);

}

static void MX_TIM16_Init(void)
{

  /* USER CODE BEGIN TIM16_Init 0 */

  /* USER CODE END TIM16_Init 0 */

  /* USER CODE BEGIN TIM16_Init 1 */

  /* USER CODE END TIM16_Init 1 */
  htim16.Instance = TIM16;
  htim16.Init.Prescaler = 63;
  htim16.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim16.Init.Period = 99;
  htim16.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  htim16.Init.RepetitionCounter = 0;
  htim16.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
  if (HAL_TIM_Base_Init(&htim16) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN TIM16_Init 2 */

  /* USER CODE END TIM16_Init 2 */

}

static void MX_TIM2_Init(void)
{

  /* USER CODE BEGIN TIM2_Init 0 */

  /* USER CODE END TIM2_Init 0 */

  TIM_Encoder_InitTypeDef sConfig = {0};
  TIM_MasterConfigTypeDef sMasterConfig = {0};

  /* USER CODE BEGIN TIM2_Init 1 */

  /* USER CODE END TIM2_Init 1 */
  htim2.Instance = TIM2;
  htim2.Init.Prescaler = 0;
  htim2.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim2.Init.Period = 4294967295;
  htim2.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  htim2.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_ENABLE;
  sConfig.EncoderMode = TIM_ENCODERMODE_TI12;
  sConfig.IC1Polarity = TIM_ICPOLARITY_RISING;
  sConfig.IC1Selection = TIM_ICSELECTION_DIRECTTI;
  sConfig.IC1Prescaler = TIM_ICPSC_DIV1;
  sConfig.IC1Filter = 0;
  sConfig.IC2Polarity = TIM_ICPOLARITY_RISING;
  sConfig.IC2Selection = TIM_ICSELECTION_DIRECTTI;
  sConfig.IC2Prescaler = TIM_ICPSC_DIV1;
  sConfig.IC2Filter = 0;
  if (HAL_TIM_Encoder_Init(&htim2, &sConfig) != HAL_OK)
  {
    Error_Handler();
  }
  sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
  sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
  if (HAL_TIMEx_MasterConfigSynchronization(&htim2, &sMasterConfig) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN TIM2_Init 2 */

  /* USER CODE END TIM2_Init 2 */

}

[Uwe Bonnes]

What is your intention? What use is information that the encoder has changed? Normally you sample the encoder when you need to process the actual value and also at a slow rate so no overflow happens.
Otherwise, not looking at your code:
- What event should trigger the DMA transfer from encoder counter to the dma memory?

[shadj]

Thank you for the reply. 

My intention is to update a buffer, from the CNT register using DMA. It should not occur based on a specific event, it should always read the value of the register.

[Uwe Bonnes]

You need some event to trigger a DMA transaction. What about setting up an EXTI interrupt on one of the decoder pins and transfer in the interrupt routine?