Posted on July 12, 2015 at 19:43
If you're going to post plots from a logic analyzer, label the signals, and for SPI show MOSI, MISO, CLK and CS pins.
Not a HAL user, but this should be a more thoughtful implementation
GPIOC->BSRRL = GPIO_BSRR_BS_13; // Inverted #CS, Set HIGH?
while((SPI3->SR & SPI_SR_TXE) != SPI_SR_TXE); // Wait for TXE to indicate empty
ms_data = SPI3->DR; // Dummy Read to clear any stale RXNE
ms_data = 0xAA; // Data you want to send
SPI3->DR = ms_data; // Write data into EMPTY register
while((SPI3->SR & SPI_SR_RXNE) != SPI_SR_RXNE); // Wait for RXNE, last bit sent already
ms_data = SPI3->DR; // Could skip this, clears *this* RXNE
GPIOC->BSRRH = GPIO_BSRR_BS_13; // Inverted #CS, Set LOW?
