STM32F4: SPI output using DMA with LL driver

[PMath.4]

Hi

I'm trying to get SPI output working using DMA with the LL drivers. I'm using CubeMX to set up the DMA and SPI and it works perfectly when I use HAL_SPI_Transmit_DMA to initiate the output. However, this is a very slow routine and I want to be able to initiate re-transmission as fast as possible. My code is attached below but I don't see any output. I'm clearly missing a bit of the jigsaw but can't find any examples to guide me.

Once I've got basic transmission working then I can pare back the routines in the loop to find the minimum needed to re-transmit.

The LED on PD8 is toggling so I know the loop is running

Help would be appreciated

while (1)
  {
		HAL_Delay(500);
		HAL_GPIO_TogglePin(GPIOD, GPIO_PIN_8);
	    // Disable DMA to load new length to be transmitted
		  LL_DMA_DisableIT_TC(DMA2,
		                     LL_DMA_STREAM_3);
		  LL_DMA_SetDataLength(DMA2,
		                       LL_DMA_STREAM_3,
		                       sizeof(dmabuff));
		  LL_DMA_ConfigAddresses(DMA2,
		                         LL_DMA_STREAM_3,
		                         (uint32_t)dmabuff,
		                         LL_SPI_DMA_GetRegAddr(SPI1),
		                         LL_DMA_DIRECTION_MEMORY_TO_PERIPH);
		  LL_SPI_EnableDMAReq_TX(SPI1);
		  LL_SPI_EnableIT_TXE(SPI1);
		  LL_DMA_EnableIT_TC(DMA2,
		                     LL_DMA_STREAM_3);
		  LL_DMA_EnableStream(DMA2,
		                       LL_DMA_STREAM_3);
		  HAL_Delay(500);
//		HAL_SPI_Transmit_DMA(&hspi1, dmabuff, sizeof(dmabuff)); // This works perfectly
    /* USER CODE END WHILE */
 
    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}

[waclawek.jan]

Read out and check/post content of DMA, SPI and relevant GPIO registers.

JW

[TDK]

One relatively quick way to solve this is to compare register settings just prior to starting the transfer between your version and HAL to determine what you've done differently.