STM32H7 SPI + DMA not working with simplex DMA transmission.

[Lmish]

SPI works fine if we use HAL_SPI_Receive_IT, but we are getting all 0's if we call HAL_SPI_Receive_DMA.

We are using below 2 apis

1) HAL_SPI_Transmit_DMA

2) HAL_SPI_Receive_DMA

call to HAL_SPI_Receive_DMA always read 0's. We handled D-cache as per Example.

There is errata for SPI simplex transmission, work around suggested was to hardware reset SPI peripheral before call to receive DMA.

We used macro __SPI1_FORCE_RESET(); but did not work.

Any help is appreciated.

Thanks in Advance.

[jakob.brunhart]

Hi,

Perhaps this will help: https://community.st.com/s/article/FAQ-DMA-is-not-working-on-STM32H7-devices.

I had a similar problem with the ADC and DMA. I have now placed the data buffer in SRAM3. Now it works.

Scatter file:

  EXEC_SRAM3 0x30040000 0x00008000 {                ; SRAM3 (32kbyte)
   *(.sram3)   
  } 

C file:

__attribute__((section (".sram3"))) 
static  uint16_t                  mgAdc3Buffer[ADC3_BUFFER_SIZE];

Regards

Jakob

[Lmish]

Hi,

Thanks for response.

We have tried this, Problem may not be due to D-Cache handling, because we have tried same code with D-Cache disabled also.

HAL_SPI_TransmitReceive_DMA() works fine with DMA for us.

The problem start when we use HAL_SPI_Transmit() function.

problem seems due to below errata

2.12 SPI

2.12.1 Spurious DMA Rx transaction after simplex Tx trafficDescriptionWith empty RXFIFO, SPI/I2S can spuriously generate a DMA read request upon enabling DMA receive traffic (by setting RXDMAEN bit), provided that the preceding completed transaction is a simplex transmission.

Workaround : Before enabling DMA Rx transfer following a completed Tx simplex transfer, perform hardware reset of the SPI/I2S peripheral

How to implement this workaround?

[jakob.brunhart]

Hi,

No idea. I'd have to get used to this myself. 

Regards

Jakob

[IBeRyUS]

__HAL_RCC_SPIX_FORCE_RESET();

__HAL_RCC_SPIX_RELEASE_RESET()

can do a full hardware reset through RCC unit. After this you need to re-initialise SPI hardware.

[Asantos]

Hi, I also have the same problem. Any solution?

Regards

Ari.