STM32 SPI: How to properly send 8bits?

[WillHuang]

I have a function here that compiles and works fine (i.e. I'm getting the output that I want) for sending 8 bit data frames on the SPI bus for the STM32F3 dev. board.

Code: [Select]

void SPI1_Transfer8(uint8_t data)
{

    uint8_t dummy;
    (volatile uint8_t)SPI1->DR = data;
    //SPI1_DR = data;
    SPI1->CR1 |= SPI_CR1_SPE;
    SPI1_Disable();
}

Although I can compile the code fine, Keil is showing me an error on line

Code: [Select]

(volatile uint8_t)SPI1->DR = data;
How can I fix this?

Thanks in advance!

[Jeroen3]

General rule: you can't cast the left side of an assignment.

Also, it will give an hardfault when try to force this.

The peripheral registers have to be accessed by half-words (16 bits) or words (32 bits).

The SPI1->DR register is already defined as an volatile uint16_t in the header. C will perform an implicit type conversion when you use it.

And you will have to wait for SPI to finish. The SPI Master is completed when RXNE = 1 and BUSY = 0.