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STM32F4 SPI Master-Slave Configuration

Question asked by thomas.julius on Dec 2, 2013
Hi, I'm trying to send data from one STM32F4 Discovery board to another via SPI in master-slave configuration. Looking at the reference manual it states that CPOL and CPHA bits to be configured the same as the master and this is also true for MSB/LSB first frame format. For configuring SPI on both boards, apart from changing

SPI_InitStruct.SPI_Mode = SPI_Mode_Master;

and

GPIO_InitStruct.GPIO_Mode = GPIO_Mode_OUT;  //for PE7 chip select

to

SPI_InitStruct.SPI_Mode = SPI_Mode_Slave;

and

GPIO_InitStruct.GPIO_Mode = GPIO_Mode_In;   //for PE7 chip select


is it just as easy as copying what I already have on my master device to the slave device?

Here is my configuration code for the master:

void init_SPI1(void){
     
    GPIO_InitTypeDef GPIO_InitStruct;
    SPI_InitTypeDef SPI_InitStruct;
     
    // enable clock for used IO pins
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
     
    /* configure pins used by SPI1
     * PA5 = SCK
     * PA6 = MISO
     * PA7 = MOSI
     */
    GPIO_InitStruct.GPIO_Pin = GPIO_Pin_7 | GPIO_Pin_6 | GPIO_Pin_5;
    GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOA, &GPIO_InitStruct);
     
    // connect SPI1 pins to SPI alternate function
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_SPI1);
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource6, GPIO_AF_SPI1);
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource7, GPIO_AF_SPI1);
     
    // enable clock for used IO pins
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOE, ENABLE);
     
    /* Configure the chip select pin
       in this case we will use PE7 */
    GPIO_InitStruct.GPIO_Pin = GPIO_Pin_7;
    GPIO_InitStruct.GPIO_Mode = GPIO_Mode_OUT;
    GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_Init(GPIOE, &GPIO_InitStruct);
     
    GPIOE->BSRRL |= GPIO_Pin_7; // set PE7 high
     
    // enable peripheral clock
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);
     
    /* configure SPI1 in Mode 0
     * CPOL = 0 --> clock is low when idle
     * CPHA = 0 --> data is sampled at the first edge
     */
    SPI_InitStruct.SPI_Direction = SPI_Direction_2Lines_FullDuplex; // set to full duplex mode, seperate MOSI and MISO lines
    SPI_InitStruct.SPI_Mode = SPI_Mode_Master;     // transmit in master mode, NSS pin has to be always high
    SPI_InitStruct.SPI_DataSize = SPI_DataSize_8b; // one packet of data is 8 bits wide
    SPI_InitStruct.SPI_CPOL = SPI_CPOL_Low;        // clock is low when idle
    SPI_InitStruct.SPI_CPHA = SPI_CPHA_1Edge;      // data sampled at first edge
    SPI_InitStruct.SPI_NSS = SPI_NSS_Soft | SPI_NSSInternalSoft_Set; // set the NSS management to internal and pull internal NSS high
    SPI_InitStruct.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_4; // SPI frequency is APB2 frequency / 4
    SPI_InitStruct.SPI_FirstBit = SPI_FirstBit_MSB;// data is transmitted MSB first
    SPI_Init(SPI1, &SPI_InitStruct);
     
    SPI_Cmd(SPI1, ENABLE); // enable SPI1
}

To connect both devices I have connected 
Master - Slave
PA5 (SCK) - PA5(SCK)
PA6(MISO) - PA7(MOSI)
PA7(MOSI) - PA6(MOSI)
PE7(CS) - PE7(CS)

Is there anything I'm doing wrong?

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