Hi there.
I'm struggling with the implementation of continuous SPI data transfer in Transmit only master mode with DMA in circular mode and enabled CRC calculation.
In any other configuration I've tried (DMA normal mode or SPI transfer with MCU polling) is CRC correctly added after data except after each data frame (5 bits) except circular mode.
In this case is CRC never generated and on physical SPI layer there is continuously transferring only data packet.
I can see that DMA transfer in circular mode is running correctly as data packet corresponds to continuously changing source data.
SPI clockrate = 50 MHz
SPI frame length = 5 bits
SPI CRC length = 5 bits
SPI inter data idleness = 1 bit
DMA mode = cicular mode
SPI communication with DMA in circular mode (configuration snippets below applied)
Thanks in advance for any tips!
For debugging purpose I'm using standard HAL_SPI_Transmit_DMA function pointed to the GPIO register
HAL_SPI_Transmit_DMA(&hspi1, &GPIOC->IDR, 1);SPI1 peripheral initialization function snippet
static void MX_SPI1_Init(void)
{
/* USER CODE BEGIN SPI1_Init 0 */
/* USER CODE END SPI1_Init 0 */
/* USER CODE BEGIN SPI1_Init 1 */
/* USER CODE END SPI1_Init 1 */
/* SPI1 parameter configuration*/
hspi1.Instance = SPI1;
hspi1.Init.Mode = SPI_MODE_MASTER;
hspi1.Init.Direction = SPI_DIRECTION_2LINES_TXONLY;
hspi1.Init.DataSize = SPI_DATASIZE_5BIT;
hspi1.Init.CLKPolarity = SPI_POLARITY_LOW;
hspi1.Init.CLKPhase = SPI_PHASE_1EDGE;
hspi1.Init.NSS = SPI_NSS_SOFT;
hspi1.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_4;
hspi1.Init.FirstBit = SPI_FIRSTBIT_MSB;
hspi1.Init.TIMode = SPI_TIMODE_DISABLE;
hspi1.Init.CRCCalculation = SPI_CRCCALCULATION_ENABLE;
hspi1.Init.CRCPolynomial = 0x20;
hspi1.Init.CRCLength = SPI_CRC_LENGTH_5BIT;
hspi1.Init.NSSPMode = SPI_NSS_PULSE_DISABLE;
hspi1.Init.NSSPolarity = SPI_NSS_POLARITY_LOW;
hspi1.Init.FifoThreshold = SPI_FIFO_THRESHOLD_01DATA;
hspi1.Init.TxCRCInitializationPattern = SPI_CRC_INITIALIZATION_ALL_ZERO_PATTERN;
hspi1.Init.RxCRCInitializationPattern = SPI_CRC_INITIALIZATION_ALL_ZERO_PATTERN;
hspi1.Init.MasterSSIdleness = SPI_MASTER_SS_IDLENESS_00CYCLE;
hspi1.Init.MasterInterDataIdleness = SPI_MASTER_INTERDATA_IDLENESS_01CYCLE;
hspi1.Init.MasterReceiverAutoSusp = SPI_MASTER_RX_AUTOSUSP_DISABLE;
hspi1.Init.MasterKeepIOState = SPI_MASTER_KEEP_IO_STATE_DISABLE;
hspi1.Init.IOSwap = SPI_IO_SWAP_DISABLE;
if (HAL_SPI_Init(&hspi1) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN SPI1_Init 2 */
/* USER CODE END SPI1_Init 2 */
}SPI MSP init function snippet
void HAL_SPI_MspInit(SPI_HandleTypeDef* hspi)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
if(hspi->Instance==SPI1)
{
/* USER CODE BEGIN SPI1_MspInit 0 */
/* USER CODE END SPI1_MspInit 0 */
/* Peripheral clock enable */
__HAL_RCC_SPI1_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
__HAL_RCC_GPIOD_CLK_ENABLE();
/**SPI1 GPIO Configuration
PA5 ------> SPI1_SCK
PD7 ------> SPI1_MOSI
*/
GPIO_InitStruct.Pin = GPIO_PIN_5;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF5_SPI1;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
GPIO_InitStruct.Pin = GPIO_PIN_7;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF5_SPI1;
HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);
/* SPI1 DMA Init */
/* SPI1_TX Init */
hdma_spi1_tx.Instance = DMA1_Stream0;
hdma_spi1_tx.Init.Request = DMA_REQUEST_SPI1_TX;
hdma_spi1_tx.Init.Direction = DMA_MEMORY_TO_PERIPH;
hdma_spi1_tx.Init.PeriphInc = DMA_PINC_DISABLE;
hdma_spi1_tx.Init.MemInc = DMA_MINC_ENABLE;
hdma_spi1_tx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;
hdma_spi1_tx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;
hdma_spi1_tx.Init.Mode = DMA_CIRCULAR;
hdma_spi1_tx.Init.Priority = DMA_PRIORITY_LOW;
hdma_spi1_tx.Init.FIFOMode = DMA_FIFOMODE_DISABLE;
if (HAL_DMA_Init(&hdma_spi1_tx) != HAL_OK)
{
Error_Handler();
}
__HAL_LINKDMA(hspi,hdmatx,hdma_spi1_tx);
/* USER CODE BEGIN SPI1_MspInit 1 */
/* USER CODE END SPI1_MspInit 1 */
}
}DMA init function snippet
static void MX_DMA_Init(void)
{
/* DMA controller clock enable */
__HAL_RCC_DMA1_CLK_ENABLE();
/* DMA interrupt init */
/* DMA1_Stream0_IRQn interrupt configuration */
HAL_NVIC_SetPriority(DMA1_Stream0_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(DMA1_Stream0_IRQn);