STM32F4 discovery SPI issue

Posted on October 09, 2016 at 07:06

Hello,

        - I am using STM32F4 discovery board to send data via SPI. i have got it working but there is a small issue. the SS pin goes high before the the mcu finishes sending data.

i am using SPI1, and used PB0 as SS.

there is my code for sending one byte:

 GPIOB->ODR &= ~(1 << PIN0); // SS is LOW

  SPI1->DR = data;

  while(! (SPI1->SR & (1 << TXE))); // wait until TX buffer is empty

  GPIOB->ODR |= (1 << PIN0); // SS is HIGH

and here is the data :

and here is the data after adding some delay before SS goes back HIGH:

Any one please know what could cause this to happen?

is it because of the TXE buffer flag goes back high before the data transmission complete?(''This is what i saw in the debugger '') and why? it is supposed to go high when there is no data in the buffer.

#!spi-!stm32f4