Hello,
I have some troubles programming a STM32F103RBT6 board.
I need to use the SPI to control engines, I initialized the SPI structure, RCC and GPIO regarding examples. When I plug the oscilloscope there is no output signal.

Here is my code :

void main()
{
RCC_Configuration();
GPIO_Configuration();
SPI_Configuration();

while(1)
{
while(SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE)== RESET){} // I saw this loop in different examples
{
SPI_I2S_SendData(SPI1, 0x4F);
}
}
}

void RCC_Configuration(void)
{
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO | RCC_APB2Periph_SPI1, ENABLE);
}

void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
/* Configure SPI pins: SCK, MISO and MOSI */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5 | GPIO_Pin_6 | GPIO_Pin_7;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(PORT_SPI, &GPIO_InitStructure);

/* Configure SPI pin : NSS */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOB, &GPIO_InitStructure);
}

void SPI_Configuration(void)
{
SPI_InitTypeDef SPI_InitStructure;

// Configuratin du SPI2 pour communiquer avec la carte moteur
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_4;
SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_LSB;
SPI_InitStructure.SPI_CRCPolynomial = 7;

SPI_Init(SPI2, &SPI_InitStructure);
SPI_Cmd(SPI2,ENABLE);
}

What is wrong in my program ?

Thank you for your help.
Flavien