How to init SPI properly

[Tommino]

Hi,

I am trying to init SPI1 (to just receive data qwith MISO) on nucleo G474RE without using HAL libraries.

Can you help me to assess why my code does not work ?

I can't see the clock eventhough SPI1 is enabled

 

void SPI1_init(){
	RCC-> APB2ENR|=(1 AHB2ENR |= (1MODER &= ~(1 AFR[0] |= (1 AFR[0] |= (1 AFR[0] |= (1 CR1 |= (1 CR1 |= (1 CR1 |= (1 CR2 |=(1CR2 |= (1CR1|= (1CR1|= (1CR1&= ~(1

[Tommino]

Ok I see

But basically in this way you have to write to DR eventhough you have just to receive data. Is this what you recommend?

Can you write the code?

[Andrew Neil]

@Tommino​ "in this way you have to write to DR even though you have just to receive data"

That's the way you'd do it "in general" - for microcontrollers that don't have this special 'read only' mode.

[waclawek.jan]

> But basically in this way you have to write to DR eventhough you have just to receive data. Is this what you recommend?

Yes. What's wrong with this?

> Can you write the code?

Read N Bytes:
for N bytes
 write byte to SPI data register
 wait until RXNE is set in status register
 read byte from SPI data register
end for
 

If you want to work with bytes rather than halfwords, you may need to think about data packing (depends on STM32 model, read RM).

JW

[Tommino]

ok thanks. I tried it and it works.

I was afraid of writing to SPI DR before reading it beacuse in some way I thought I could have readback what I wrote. How is this prevented?

[Andrew Neil]

@Tommino​ "How is this prevented?"

There'll be a status bit that tells you when a transfer has completed.

 

On this chip, you also have read & write FIFOs