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SPI modes?

Question asked by s.b.003 on May 27, 2013
Hello!
This is my code for SPI:
RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI2, ENABLE);
SPI_InitTypeDef  spi;
spi.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
spi.SPI_Mode = SPI_Mode_Master;
spi.SPI_DataSize = SPI_DataSize_8b;//16
spi.SPI_CPOL = SPI_CPOL_High;
spi.SPI_CPHA = SPI_CPHA_2Edge;
spi.SPI_NSS = SPI_NSS_Soft;
spi.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_4;
spi.SPI_FirstBit = SPI_FirstBit_MSB;
spi.SPI_CRCPolynomial = 7;
SPI_Init(SPI2, &spi);
NVIC_EnableIRQ(SPI2_IRQn);
SPI_I2S_ITConfig(SPI2, SPI_I2S_IT_RXNE, ENABLE);
SPI_Cmd(SPI2, ENABLE);
SPI_NSSInternalSoftwareConfig(SPI2, SPI_NSSInternalSoft_Set);
and IRQ Handler:
void SPI2_IRQHandler(){
    if (SPI_I2S_GetITStatus(SPI2, SPI_I2S_IT_RXNE) == SET){
        uint16_t spi_data16 = SPI_I2S_ReceiveData16(SPI2);
    }
}



According to stm32f30x_spi.c there are several SPI modes: "Interrupt mode", "Polling mode" and "DMA mode".
In "Interrupt mode" I receive some data from my connected device. 
In "Polling mode" (setup is the same as in Interrupt mode but without NVIC_EnableIRQ and SPI_I2S_ITConfig?) I made a function to send/receive 8 bits:

uint8_t SPI_SendRead8(uint8_t ToSend8){
    while((SPI2->SR & (uint8_t)SPI_I2S_FLAG_TXE) == RESET){;}
    SPI2->DR = ToSend8;
    while ((SPI2->SR & (uint8_t)SPI_I2S_FLAG_RXNE) == RESET) {;}
    return SPI2->DR;
}
but I receive invalid data. I want to simultaneously readwrite to know what data I receive at this moment. There is an error in my code?

Also SPI_DataSize_8b; and SPI_DataSize_16b; SPI_BaudRatePrescaler parameters - which should I use with the AD7738 ADC?

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