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dh_leslie
Associate III
April 24, 2025
Question

about gpdma transmission size

  • April 24, 2025
  • 3 replies
  • 716 views

I am porting code from G473 to U575 because I need more flash and ram.

Then I meet some issues on gpdma transmission size.

For G473, I use dma to transfer data to timer ARR likes:

uint16_t buf[65536] = { ..... };

HAL_TIM_Base_Start_DMA(&htim1, (uint32_t *)buf, 65536);

For U575, the code doesn't work because the size have to be 65536 * sizeof(uint16_t), not the number of buf.

Is there any way to figure it out?

3 replies

TDK
TDK
Super User
April 24, 2025

The code presented cannot work, either at 65536 or at 65536 * sizeof(uint16_t).

 

The CNDT register field is 16 bits and accept a maximum value of 65535.

The HAL_TIM_Base_Start_DMA also accept a max value of 65535.

/**
 * @brief Starts the TIM Base generation in DMA mode.
 * @PAram htim TIM Base handle
 * @PAram pData The source Buffer address.
 * @PAram Length The length of data to be transferred from memory to peripheral.
 * @retval HAL status
 */
HAL_StatusTypeDef HAL_TIM_Base_Start_DMA(TIM_HandleTypeDef *htim, const uint32_t *pData, uint16_t Length)
{

 

 

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D
dh_leslieAuthor
Associate III
April 24, 2025

Yes, you are right.

Currently, I only use 16384 in G473. But I want to port code to U575 and use more buf in DMA.

And I found the definition is different between G4 and U5 in DMA size.

TDK
TDK
Super User
April 24, 2025

> And I found the definition is different between G4 and U5 in DMA size.

No it's not.

https://github.com/STMicroelectronics/stm32u5xx-hal-driver/blob/819eaeffea70bb4bc2319111ea0fcc21c9788189/Src/stm32u5xx_hal_tim.c#L541

https://github.com/STMicroelectronics/stm32g4xx-hal-driver/blob/1a4f1ca138a19dfe42becc50975f11a1e7554e31/Src/stm32g4xx_hal_tim.c#L541

 

"If you feel a post has answered your question, please click ""Accept as Solution""."
D
dh_leslieAuthor
Associate III
April 25, 2025

New question: How to configure linked list DMA to update TIM->ARR each time when Update Event generated?

/**
 * @brief DMA Linked-list xFreqList configuration
 * None
 * @retval None
 */
HAL_StatusTypeDef MX_xFreqList_Config(void)
{
 HAL_StatusTypeDef ret = HAL_OK;
 /* DMA node configuration declaration */
 DMA_NodeConfTypeDef pNodeConfig;

 /* Set node configuration ################################################*/
 pNodeConfig.NodeType = DMA_GPDMA_LINEAR_NODE;
 pNodeConfig.Init.Request = GPDMA1_REQUEST_TIM15_UP;
 pNodeConfig.Init.BlkHWRequest = DMA_BREQ_SINGLE_BURST;
 pNodeConfig.Init.Direction = DMA_MEMORY_TO_PERIPH;
 pNodeConfig.Init.SrcInc = DMA_SINC_INCREMENTED;
 pNodeConfig.Init.DestInc = DMA_DINC_FIXED;
 pNodeConfig.Init.SrcDataWidth = DMA_SRC_DATAWIDTH_HALFWORD;
 pNodeConfig.Init.DestDataWidth = DMA_DEST_DATAWIDTH_HALFWORD;
 pNodeConfig.Init.SrcBurstLength = 1;
 pNodeConfig.Init.DestBurstLength = 1;
 pNodeConfig.Init.TransferAllocatedPort = DMA_SRC_ALLOCATED_PORT0|DMA_DEST_ALLOCATED_PORT1;
 pNodeConfig.Init.TransferEventMode = DMA_TCEM_BLOCK_TRANSFER;
 pNodeConfig.TriggerConfig.TriggerPolarity = DMA_TRIG_POLARITY_MASKED;
 pNodeConfig.DataHandlingConfig.DataExchange = DMA_EXCHANGE_NONE;
 pNodeConfig.DataHandlingConfig.DataAlignment = DMA_DATA_RIGHTALIGN_ZEROPADDED;
 pNodeConfig.SrcAddress = (uint32_t)TimerTable;
 pNodeConfig.DstAddress = (uint32_t)&(TIM15->ARR);
 pNodeConfig.DataSize = 4*2;

 /* Build FreqTimerTable1 Node */
 ret |= HAL_DMAEx_List_BuildNode(&pNodeConfig, &FreqTimerTable1);

 /* Insert FreqTimerTable1 to Queue */
 ret |= HAL_DMAEx_List_InsertNode_Tail(&xFreqList, &FreqTimerTable1);

 ret |= HAL_DMAEx_List_SetCircularMode(&xFreqList);

 return ret;
}
 MX_xFreqList_Config();
 HAL_DMAEx_List_LinkQ(&handle_GPDMA1_Channel0, &xFreqList);
 HAL_DMAEx_List_Start(&handle_GPDMA1_Channel0);
 HAL_TIM_Base_Start(&htim15);

 

P
psabela
Associate III
April 25, 2025

Follow this ST video as a guide: https://youtu.be/jKOhRfb3gvk?si=xX4p7RoMXyTvPXEC

D
dh_leslieAuthor
Associate III
April 25, 2025

I tried the code in the video. It works on ADC but not on Timer.

Also I tried standard request mode dma with HAL_TIM_Base_Start_DMA. ARR was being updated.

I am confused why it does not work with linked-list mode dma.

D
dh_leslieAuthor
Associate III
April 25, 2025
 uint16_t StartTable = 1;
 MX_xFreqQ_Config();
 HAL_DMAEx_List_LinkQ(&handle_GPDMA1_Channel0, &xFreqList);
 HAL_DMAEx_List_Start(&handle_GPDMA1_Channel0);
 HAL_TIM_Base_Start_DMA(&htim15, (uint32_t *)&StartTable, 2);

Things are weird.

I opened an other standard request mode dma for the same timer, and ran HAL_TIM_Base_Start_DMA. 

Then the linked-list dma started working.

I think maybe I need to set bit TIMx_EGR.UG to force ARR update, but it's not the key.

Why? very confused.

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