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strange spi signal problem

Question asked by kaya.cihan on Feb 28, 2013
Latest reply on Feb 4, 2014 by Clive One
Hello everyone,
We are using STM32F215VGT on our project. When we send data over SPI from STM32F2, clock and data signals are not square wave. i attached clock signal.
On our board, there is TXB0106 between STM32F2 and receiver. We removed TXB0106 but signals didn't change. Also output signal of TXB0106 is corrupted. I also attached SPI clock signal of STM32F2 and output signal of TXB0106.
Blue signal is SPI clock signal of STM32F2 and yellow signal is  output signal of TXB0106.
Also we tried the codes on STM3220E eval kit but result is same.
How can we fix it?
Our SPI configuration is:

    SPI_InitTypeDef  SPI_InitStructure;
    GPIO_InitTypeDef GPIO_InitStructure;


    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
    GPIO_PinAFConfig(GPIOB, GPIO_PinSource10, SPI_SCK_AF);
    GPIO_PinAFConfig(GPIOB, GPIO_PinSource15, SPI_MOSI_AF);

    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_UP;

    /*!< SPI SCK pin configuration */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

    /*!< SPI MOSI pin configuration */
    GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_15;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

    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_2Edge;
    SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;
    SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_8;

    SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
    SPI_InitStructure.SPI_CRCPolynomial = 7;
    SPI_Init(SPI, &SPI_InitStructure);