Question
different behaviour of my chip select with different payload size
Hi,
I am working with stm32H743II Board - which define SPI4 block as SPI Master according to the following:
void MX_SPI4_Init(void)
{
/* USER CODE BEGIN SPI4_Init 0 */
/* USER CODE END SPI4_Init 0 */
/* USER CODE BEGIN SPI4_Init 1 */
/* USER CODE END SPI4_Init 1 */
/* SPI4 parameter configuration*/
hspi4.Instance = SPI4;
hspi4.Init.Mode = SPI_MODE_MASTER;
hspi4.Init.Direction = SPI_DIRECTION_2LINES;
hspi4.Init.DataSize = SPI_DATASIZE_8BIT;
hspi4.Init.CLKPolarity = SPI_POLARITY_LOW;
hspi4.Init.CLKPhase = SPI_PHASE_1EDGE;
hspi4.Init.NSS = SPI_NSS_HARD_OUTPUT;
hspi4.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_8;
hspi4.Init.FirstBit = SPI_FIRSTBIT_MSB;
hspi4.Init.TIMode = SPI_TIMODE_DISABLE;
hspi4.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
hspi4.Init.CRCPolynomial = 0x7;
hspi4.Init.NSSPMode = SPI_NSS_PULSE_ENABLE;
hspi4.Init.NSSPolarity = SPI_NSS_POLARITY_LOW;
hspi4.Init.FifoThreshold = SPI_FIFO_THRESHOLD_08DATA;
hspi4.Init.TxCRCInitializationPattern = SPI_CRC_INITIALIZATION_ALL_ZERO_PATTERN;
hspi4.Init.RxCRCInitializationPattern = SPI_CRC_INITIALIZATION_ALL_ZERO_PATTERN;
hspi4.Init.MasterSSIdleness = SPI_MASTER_SS_IDLENESS_00CYCLE;
hspi4.Init.MasterInterDataIdleness = SPI_MASTER_INTERDATA_IDLENESS_00CYCLE;
hspi4.Init.MasterReceiverAutoSusp = SPI_MASTER_RX_AUTOSUSP_DISABLE;
hspi4.Init.MasterKeepIOState = SPI_MASTER_KEEP_IO_STATE_ENABLE;
hspi4.Init.IOSwap = SPI_IO_SWAP_DISABLE;
if (HAL_SPI_Init(&hspi4) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN SPI4_Init 2 */
/* USER CODE END SPI4_Init 2 */
}and HAL_SPI_MspInit is defined according to the following:
void HAL_SPI_MspInit(SPI_HandleTypeDef* hspi)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
if(hspi->Instance==SPI4)
{
/* USER CODE BEGIN SPI4_MspInit 0 */
/* USER CODE END SPI4_MspInit 0 */
/* Peripheral clock enable */
__HAL_RCC_SPI4_CLK_ENABLE();
__HAL_RCC_GPIOE_CLK_ENABLE();
/**SPI4 GPIO Configuration
PE4 ------> SPI4_NSS
PE5 ------> SPI4_MISO
PE6 ------> SPI4_MOSI
PE12 ------> SPI4_SCK
*/
GPIO_InitStruct.Pin = GPIO_PIN_4|GPIO_PIN_5|GPIO_PIN_6|GPIO_PIN_12;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_PULLDOWN;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF5_SPI4;
HAL_GPIO_Init(GPIOE, &GPIO_InitStruct);
//HAL_NVIC_SetPriority(SPI4_IRQn, 1, 1);
//HAL_NVIC_EnableIRQ(SPI4_IRQn);
/* USER CODE BEGIN SPI4_MspInit 1 */
/* USER CODE END SPI4_MspInit 1 */
}when I'm running a single SPI transaction using
HAL_SPI_TransmitReceive i have different behavior with different payload size:
when i am use samll payload = "aabbccddaabbccdd" then i get the following:
but when i am using larger payload = "aabbccddaabbccddaabbccdd" then i get the following:
can someone please explain why there is different behavior of the chip select with the number of cycle clocks?
