I have a problem of using SPI in STM32H753VIT6 CHIP

[KDG]

Hello,

I'm trying to do SPI communication with an ADE1201 chip through an STM32H753VIT6 chip.

The maximum allowed frequency of the ADE1201 is 10MHZ, so I set the SPI to communicate with the MCU at 6.25MHZ.

(The clock for SPI communication is 25MHZ, and I set the PRESCALER value to 4).

However, a strange phenomenon was observed.

 

I observed through the scope that the SPI CS signal should be 0 continuously, but it turns to 1 in the middle.(See attached photo).

However, if I set the PRESCALER value to 8, the CS signal is continuously output as 0.

What could be the cause? And how can I solve this?

Could this be due to the usage of HAL_SPI_TransmitReceive function?

[Pierre_Paris]

Hello @KDG,

Thank you for your question !

Here some remark :

• Can you share your code ? At least your SPI parameter configuration and what API you called (HAL_SPI_TransmitReceive, that's it?)
• When prescaler = 8 (f = 3.12 MHz), the behavior is normal but when prescaler = 4 (f = 6.25MHz), there is sometimes the CS which turns to 1. This is the only change you made between both screen right ?
• Also, do you have the values of registers ? SPI_CFG1 ? SPI_CFG2 (especially SSOE, SSOM & SSM) ? In master mode, the SS can be used either as an output or an input. As an input it can prevent a multi master bus collision, and as an output it can drive a slave select signal of a single slave. How many masters are on the bus ? 

Kind Regards,

Pierre

[KDG]

Thanks for the remark @Pierre_Paris 

These are the answers for your remarks

• static 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_HIGH;
  hspi4.Init.CLKPhase = SPI_PHASE_2EDGE;
  hspi4.Init.NSS = SPI_NSS_HARD_OUTPUT;
  hspi4.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_4;
  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_DISABLE;
  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 the API IS
  HAL_SPI_TransmitReceive(&hspi4, u8_R_head_buffer, u8_R_buffer, 4 , 10 );
• Yes, that is the only change made between both screeen
  
  
• These are the values for the registers that you required
  • 
    
    
  • There are only one master on the bus 
    
    
    

I wonder if this would be enough for your remarks.

Thank you.

Sincerely,

KDG

[Pierre_Paris · Accepted solution]

Hello @KDG ,

As I can see, here some remarks :

• You declares NSSPMode to SPI_NSS_PULSE_ENABLE. This mode is activated by the SSOM bit in the SPIx_CR2 register. For SSOM = 1, SPI data frames are interleaved with SS non active pulses when MIDI[3:0]>1. That's explaining the behavior of your SPI4 CS line. According to RM0433, we are in a situation quite similar as shown in figure 620.Can you change to SPI_NSS_PULSE_DISABLE ? Does that solve your issue ? 

• It's recommended to set MasterKeepIOState to SPI_MASTER_KEEP_IO_STATE_ENABLE to avoid glitches.

Best Regards,

Pierre

[KDG]

Thanks @Pierre_Paris 

By your remarks, my problem is solved.