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Spi 3 problem STM32F429

Question asked by vugs.michel on Jun 3, 2014
Latest reply on Jun 3, 2014 by vugs.michel

In our project we need the Spi 3 channel to control an Oled display. The display is connected to pins: D6, B3 and B4 so the Spi 3 pins need to be remapped to those pins.

The remapping is done in the spi3 init function:

void Spi3_Init(void)
     GPIO_InitTypeDef GPIO_InitStructure;
     SPI_InitTypeDef  SPI_InitStructure;

     RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
     RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
     RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI3 , ENABLE);

     GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3 | GPIO_Pin_4;
     GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
     GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
     GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
     GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
     GPIO_Init(GPIOB, &GPIO_InitStructure);

     GPIO_PinAFConfig(GPIOB, GPIO_PinSource3, GPIO_AF_SPI3);
     GPIO_PinAFConfig(GPIOB, GPIO_PinSource4, GPIO_AF_SPI3);

     GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;
     GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
     GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
     GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
     GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
     GPIO_Init(GPIOD, &GPIO_InitStructure);

     GPIO_PinAFConfig(GPIOD, GPIO_PinSource6, GPIO_AF_SPI3);

     SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
     SPI_InitStructure.SPI_Mode = SPI_Mode_Master;
     SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b;
     SPI_InitStructure.SPI_CPOL = SPI_CPOL_High;
     SPI_InitStructure.SPI_CPHA = SPI_CPHA_1Edge;
     SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;
     SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_2;
     SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
     SPI_InitStructure.SPI_CRCPolynomial = 7;
     SPI_Init(SPI3, &SPI_InitStructure);
     SPI_Cmd(SPI3, ENABLE);           /* Enable the SPI  */


After this function is called, we do some basic data sending with this function:

while (1)
          SPI_I2S_SendData(SPI3, 0x55);

we did some basic testing with a oscilloscope to check the spi is working but can only see that the clock pin is working. The Mosi pin does nothing. 

If we make a GPIO pin of the Mosi pin we can toggle the pin.

Are there things we have missed? 

My sincerly