void USART3_Configuration(void)
{
USART_InitTypeDef USART_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3, ENABLE);

/* Connect USART pins to AF7 */
GPIO_PinAFConfig(GPIOB, GPIO_PinSource10,GPIO_AF_USART3);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource11, GPIO_AF_USART3);

/* Configure USART Tx and Rx as alternate function push-pull */
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;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
GPIO_Init(GPIOB, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;
GPIO_Init(GPIOB, &GPIO_InitStructure);

/* Enable the USART OverSampling by 8 */
USART_OverSampling8Cmd(USART3, ENABLE);

USART_InitStructure.USART_BaudRate = 115200;
USART_InitStructure.USART_WordLength = USART_WordLength_8b;
USART_InitStructure.USART_StopBits = USART_StopBits_1;
USART_InitStructure.USART_Parity = USART_Parity_No;
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
USART_Init(USART3, &USART_InitStructure);

/* Enable USART */
USART_Cmd(USART3, ENABLE);
}

void Putchar(int8_t x)
{
uint16_t Data;
USART_SendData(USART3,(uint16_t)x);
while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET) {};
}
//-----------------------------------------------------------------------
int main(void)
{
RCC_Configuration();
GPIO_Configuration();
USART2_Configuration();
USART3_Configuration();


while (1)
{

volatile int x_i = 0;
Putchar(0x34);
for(x_i=0;x_i<1000;x_i++);

}
}

int putchar_usart(void * port, int litera)
{
    while (    !USART_GetFlagStatus((USART_TypeDef *)port, USART_FLAG_TXE) );
    USART_SendData((USART_TypeDef *)port, litera);
    return litera;
}