How To Enable SPI Pulsed mode?

[HAlzo]

Hi,

I am reading a burst of data 3072 half words from slave SPI device.

The Slave device requires NSS to be released after each half word transmission.

When I loop on HAL_SPI_TransmitReceive() function with size =1 for 3072 times it's OK.

but when I try to do it in one shoot using Size() with size = 3072 , the NSS is set low for the whole 3072.

the same happens when I try to use DMA "SPI NSS is low during the whole time of the 3072 half words".

I set NSSPMode = SPI_NSS_PULSE_ENABLE;

Here's my SPI Initialization tag.

hspi4.Instance = SPI4;
  hspi4.Init.Mode = SPI_MODE_MASTER;
  hspi4.Init.Direction = SPI_DIRECTION_2LINES;
  hspi4.Init.DataSize = SPI_DATASIZE_16BIT;
  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 = 0x0;
  hspi4.Init.NSSPMode = SPI_NSS_PULSE_ENABLE;
  hspi4.Init.NSSPolarity = SPI_NSS_POLARITY_LOW;
  hspi4.Init.FifoThreshold = SPI_FIFO_THRESHOLD_01DATA;
  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();
  }

How can I generate pulse on NSS after each half word if I am reading the whole data in one shot or using DMA?

In the next picture NSS in Yellow and SCK in green, this is the required pattern, I get it when sending data one by one

and in the next picture 1st half word is sent in one command and after that I start DMA,

you can see that NSS is kept low during the whole data transmission

Best Regards

Hossam Alzomor

[waclawek.jan]

Set nonzero SPI_CFG2.MIDI, read Slave select (SS) pin management subchapter of the SPI chapter in RM.

JW

[HAlzo · Accepted solution]

thanks @Community member​ 

it was the MIDI, I should use a value greater than 1

Here's the working configurations

 hspi4.Instance = SPI4;
  hspi4.Init.Mode = SPI_MODE_MASTER;
  hspi4.Init.Direction = SPI_DIRECTION_2LINES;
  hspi4.Init.DataSize = SPI_DATASIZE_16BIT;
  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 = 0x0;
  hspi4.Init.NSSPMode = SPI_NSS_PULSE_ENABLE;
  hspi4.Init.NSSPolarity = SPI_NSS_POLARITY_LOW;
  hspi4.Init.FifoThreshold = SPI_FIFO_THRESHOLD_01DATA;
  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_02CYCLE;
  hspi4.Init.MasterReceiverAutoSusp = SPI_MASTER_RX_AUTOSUSP_DISABLE;
  hspi4.Init.MasterKeepIOState = SPI_MASTER_KEEP_IO_STATE_ENABLE;
  hspi4.Init.IOSwap = SPI_IO_SWAP_DISABLE;

Hossam Alzomor