We need the register-based low level SPI R/W drive for STM32C031C6

[RongShengWang]

1. CubeMX only allows HAL or LL for SPI and other peripherals. STM32C031C6 itself provides the good SPI clock rate. 

   SPI LL API function only allows two-byte R/W.. The slave STPM34 Meter IC requires 4-Byte SPI R/W. So we have to choose HAL SPI API calls, such as HAL_SPI_TransmitReceive().   

    However HAL introduces a big delay (15 us or more) between two consecutive HAL SPI-API calls. We need 6 SPI-API calls within 128us for our application,  This big delay inserted by HAL makes it impossible. .

2. The only solution is to write the register low level SPI R/W functions. Is it possible to write it under the current CubeMx IDE compiler for STM32C031C6? Could you provide us the solutions?

Thanks,

Rong

[Andrew Neil]

The auto-generated code just does the initialisation stuff - you can write your own register-level code to do the runtime sending thereafter.

[Amel NASRI]

Hi @RongShengWang ,

Here 2 examples with SPI LL APIs using STM32C031: https://github.com/STMicroelectronics/STM32CubeC0/tree/main/Projects/NUCLEO-C031C6/Examples_LL/SPI.

You can start from the IOC file of each example and adapt it to yours needs. 

-Amel

[RongShengWang]

Hi, Almel,

   SPI LL API function only allows two-byte R/W each time. The slave side requires 4-Byte SPI R/W each time. We can't use LL for the Master SPI.

   HAL introduces a big delay (15 us -20 us) between two consecutive HAL SPI-API calls (such as two calls to HAL_SPI_TransmitReceive()).  . We need 6 SPI-API calls within 128us for our application,  This big delay inserted by HAL between any two consecutive HAL SPI-API calls makes  it impossible. .

Could you explain how your LL example can overcome the problem in the above?

Thanks

Rong

[RongShengWang]

Hi, Andrew Neil,

    "you can write your own register-level code to do the runtime" - Could you provide me with a reference code?

     Thanks,

Rong

[Andrew Neil]

Sorry, no.

I suggest you look at the LL code, and adapt that...

[RongShengWang]

Hi,

    "you can write your own register-level code to do the runtime sending thereafter." - The CubeMX compiler may not recognize the own register-level code, such as "SPI1->DR = (uint16_t)(tx_data << 8);", which I copied from some

reference projects using STM32 SPI registers to handle SPI.

    How to make CubeMX compiler to recognize it?

   Thanks,

Rong

[Andrew Neil]

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@RongShengWang wrote:

The CubeMX compiler ...    

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You mean the CubeIDE compiler - ie, GCC ?

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@RongShengWang wrote:

... may not recognize the own register-level code, such as "SPI1->DR = (uint16_t)(tx_data << 8);"

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What makes you say that?

[RongShengWang]

I am using CubeIDE compiler for everything now.

[RongShengWang]

Hi, Almel,

   SPI LL API function only allows two-byte R/W each time. The slave side requires 4-Byte SPI R/W each time. We can't use LL for the Master SPI because the protocol is 4-byte based.

    Besides We need 6 SPI-API calls within 128us for our application.

    Could you explain why LL can satisfy the above requirement?

Thanks,

Rong