How to receive stream through SPI using DMA ?

[simo zz]

Hi,

I am using an STM32F407VGx MCU and I am trying to receive data from SPI1 using DMA.

STM32CubeIDE generated code for the SPI1 is the following:

void MX_SPI1_Init(void)
{
  LL_SPI_InitTypeDef SPI_InitStruct = {0};
 
  LL_GPIO_InitTypeDef GPIO_InitStruct = {0};
 
  /* Peripheral clock enable */
  LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_SPI1);
  
  LL_AHB1_GRP1_EnableClock(LL_AHB1_GRP1_PERIPH_GPIOA);
  /**SPI1 GPIO Configuration  
  PA4   ------> SPI1_NSS
  PA5   ------> SPI1_SCK
  PA6   ------> SPI1_MISO
  PA7   ------> SPI1_MOSI 
  */
  GPIO_InitStruct.Pin = LL_GPIO_PIN_4|LL_GPIO_PIN_5|LL_GPIO_PIN_6|LL_GPIO_PIN_7;
  GPIO_InitStruct.Mode = LL_GPIO_MODE_ALTERNATE;
  GPIO_InitStruct.Speed = LL_GPIO_SPEED_FREQ_VERY_HIGH;
  GPIO_InitStruct.OutputType = LL_GPIO_OUTPUT_PUSHPULL;
  GPIO_InitStruct.Pull = LL_GPIO_PULL_NO;
  GPIO_InitStruct.Alternate = LL_GPIO_AF_5;
  LL_GPIO_Init(GPIOA, &GPIO_InitStruct);
 
  /* SPI1 DMA Init */
  
  /* SPI1_RX Init */
  LL_DMA_SetChannelSelection(DMA2, LL_DMA_STREAM_0, LL_DMA_CHANNEL_3);
 
  LL_DMA_SetDataTransferDirection(DMA2, LL_DMA_STREAM_0, LL_DMA_DIRECTION_PERIPH_TO_MEMORY);
 
  LL_DMA_SetStreamPriorityLevel(DMA2, LL_DMA_STREAM_0, LL_DMA_PRIORITY_VERYHIGH);
 
  LL_DMA_SetMode(DMA2, LL_DMA_STREAM_0, LL_DMA_MODE_NORMAL);
 
  LL_DMA_SetPeriphIncMode(DMA2, LL_DMA_STREAM_0, LL_DMA_PERIPH_NOINCREMENT);
 
  LL_DMA_SetMemoryIncMode(DMA2, LL_DMA_STREAM_0, LL_DMA_MEMORY_INCREMENT);
 
  LL_DMA_SetPeriphSize(DMA2, LL_DMA_STREAM_0, LL_DMA_PDATAALIGN_BYTE);
 
  LL_DMA_SetMemorySize(DMA2, LL_DMA_STREAM_0, LL_DMA_MDATAALIGN_BYTE);
 
  LL_DMA_DisableFifoMode(DMA2, LL_DMA_STREAM_0);
 
  SPI_InitStruct.TransferDirection = LL_SPI_FULL_DUPLEX;
  SPI_InitStruct.Mode = LL_SPI_MODE_SLAVE;
  SPI_InitStruct.DataWidth = LL_SPI_DATAWIDTH_8BIT;
  SPI_InitStruct.ClockPolarity = LL_SPI_POLARITY_LOW;
  SPI_InitStruct.ClockPhase = LL_SPI_PHASE_1EDGE;
  SPI_InitStruct.NSS = LL_SPI_NSS_HARD_INPUT;
  SPI_InitStruct.BitOrder = LL_SPI_MSB_FIRST;
  SPI_InitStruct.CRCCalculation = LL_SPI_CRCCALCULATION_DISABLE;
  SPI_InitStruct.CRCPoly = 10;
  LL_SPI_Init(SPI1, &SPI_InitStruct);
  LL_SPI_SetStandard(SPI1, LL_SPI_PROTOCOL_MOTOROLA);
 
}

while this is my additional code to set memory size and address of the memory buffer:

unsigned char sp1_tc;
unsigned char spi1_rx_buff[10];
void MX_SPI1_DMA_Addr_Size_Init(void)
{
	/* SPI1_RX => DMA2, LL_DMA_STREAM_0, LL_DMA_CHANNEL_3 */
	LL_DMA_SetDataLength(DMA2, LL_DMA_STREAM_0, sizeof(spi1_rx_buff));
	LL_DMA_SetMemoryAddress(DMA2, LL_DMA_STREAM_0, (unsigned) &spi1_rx_buff);
	LL_DMA_SetPeriphAddress(DMA2, LL_DMA_STREAM_0, LL_SPI_DMA_GetRegAddr(SPI1));
	LL_DMA_EnableIT_TC(DMA2, LL_DMA_STREAM_0);
	LL_DMA_EnableStream(DMA2, LL_DMA_STREAM_0);
 
	LL_SPI_EnableDMAReq_RX(SPI1);
	LL_SPI_Enable(SPI1);
}

ISR:

void DMA2_Stream0_IRQHandler(void)
{
  /* USER CODE BEGIN DMA2_Stream0_IRQn 0 */
  if(LL_DMA_IsActiveFlag_TC0(DMA2))
  {
	  LL_DMA_ClearFlag_TC0(DMA2);
	  sp1_tc = 1;
  }
  /* USER CODE END DMA2_Stream0_IRQn 0 */
  /* USER CODE BEGIN DMA2_Stream0_IRQn 1 */
 
  /* USER CODE END DMA2_Stream0_IRQn 1 */
}

However, I am unable to correctly receive the stream basically because I never detect spi1_tc as 1. Debugging the core also always shows nothing.

DMA2 is also used for USART1 (Stream 2 on RX, Stream 7 on TX).

So what's wrong in my setup ?

Thanks.

s.

[simo zz · Accepted solution]

Solved. The trick is to temporally disable the stream and re-enable it once the job on the buffer is done.

s.