Doubt on DMA Settings generated by IDE

[simo zz]

Hi,

I would like to use DMA request for USART1 RX and SPI1 RX. The AN4301 at section 4.3 states:

Software sequence to enable DMA

The following software sequence applies when enabling DMA:

1. Configure the suitable DMA stream.
2. Enable the DMA stream used (set the EN bit in the DMA_SxCR register).
3. Enable the peripheral used. DMA request enable bit in the peripheral control register

should be set ("1").

But the code generated for DMA settings for USART1 RX and SPI1 RX is incomplete and does not agree to what the AN says. Using LL libraries, the code generated for the USART is the following:

void MX_USART1_UART_Init(void)
{
  LL_USART_InitTypeDef USART_InitStruct = {0};
 
  LL_GPIO_InitTypeDef GPIO_InitStruct = {0};
 
  /* Peripheral clock enable */
  LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_USART1);
  
  LL_AHB1_GRP1_EnableClock(LL_AHB1_GRP1_PERIPH_GPIOA);
  /**USART1 GPIO Configuration  
  PA9   ------> USART1_TX
  PA10   ------> USART1_RX
  PA11   ------> USART1_CTS
  PA12   ------> USART1_RTS 
  */
  GPIO_InitStruct.Pin = LL_GPIO_PIN_9|LL_GPIO_PIN_10|LL_GPIO_PIN_11|LL_GPIO_PIN_12;
  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_UP;
  GPIO_InitStruct.Alternate = LL_GPIO_AF_7;
  LL_GPIO_Init(GPIOA, &GPIO_InitStruct);
 
  /* USART1 DMA Init */
  
  /* USART1_RX Init */
  LL_DMA_SetChannelSelection(DMA2, LL_DMA_STREAM_5, LL_DMA_CHANNEL_4);
 
  LL_DMA_SetDataTransferDirection(DMA2, LL_DMA_STREAM_5, LL_DMA_DIRECTION_PERIPH_TO_MEMORY);
 
  LL_DMA_SetStreamPriorityLevel(DMA2, LL_DMA_STREAM_5, LL_DMA_PRIORITY_LOW);
 
  LL_DMA_SetMode(DMA2, LL_DMA_STREAM_5, LL_DMA_MODE_CIRCULAR);
 
  LL_DMA_SetPeriphIncMode(DMA2, LL_DMA_STREAM_5, LL_DMA_PERIPH_NOINCREMENT);
 
  LL_DMA_SetMemoryIncMode(DMA2, LL_DMA_STREAM_5, LL_DMA_MEMORY_NOINCREMENT);
 
  LL_DMA_SetPeriphSize(DMA2, LL_DMA_STREAM_5, LL_DMA_PDATAALIGN_BYTE);
 
  LL_DMA_SetMemorySize(DMA2, LL_DMA_STREAM_5, LL_DMA_MDATAALIGN_BYTE);
 
  LL_DMA_DisableFifoMode(DMA2, LL_DMA_STREAM_5);
 
  USART_InitStruct.BaudRate = 115200;
  USART_InitStruct.DataWidth = LL_USART_DATAWIDTH_8B;
  USART_InitStruct.StopBits = LL_USART_STOPBITS_1;
  USART_InitStruct.Parity = LL_USART_PARITY_NONE;
  USART_InitStruct.TransferDirection = LL_USART_DIRECTION_TX_RX;
  USART_InitStruct.HardwareFlowControl = LL_USART_HWCONTROL_NONE;
  USART_InitStruct.OverSampling = LL_USART_OVERSAMPLING_16;
  LL_USART_Init(USART1, &USART_InitStruct);
  LL_USART_ConfigAsyncMode(USART1);
  LL_USART_Enable(USART1);
 
}

It doesn't enable the DMA stream using

void LL_DMA_EnableStream(DMA_TypeDef *DMAx, uint32_t Stream)

function (I suppose this must be done by the user setting memory address and data size), but it enables the USART1.

On the other hand, the code generated for the SPI does not enable the peripheral:

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);
 
}

So why this difference in auto-generated code ?

s.