I'm trying to transmit ( using stm32f407) two hex numbers just like the datasheet explains (attached picture), but only the second number is being transmitted (checked with logic analyzer). Code is:

SPI1->CR1 |= (1 << 6); // enable SPI1
SPI1->DR = 0x86;                  // transmit 0x86
while ((SPI1->SR >> 1)==0);  // wait until TXE is set
SPI1->DR = 0x85;     // transmit 0x85

Anything quick that i am missing?
thanks

 

Did you configure the SPI module correctly? Show all your code.

You need to test the TXE bit in SR.
#define SPI_TXE 0x0002

while ( (SPI1->SR & SPI_TXE) == 0);

Do you have an oscilloscope?

 

Yeap, that worked. I thought this: while ((SPI1->SR >> 1)==0);
was doing the same thing.
Thanks, i'll probably start some more threads as i try to make SPI (transmit and receive) to work.

 

Yeap, that worked. I thought this: while ((SPI1->SR >> 1)==0);
was doing the same thing.
Thanks, i'll probably start some more threads as i try to make SPI (transmit and receive) to work.

while ((SPI1->SR >> 1)==0);

does not take into account that all the other bits could be set.