/* Enable USART clock */
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
    /* Connect PXx to USARTx_Tx */
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_7);
    /* Connect PXx to USARTx_Rx */
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_7);
    /* Configure USART Tx as alternate function push-pull */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOA, &GPIO_InitStructure);
    /* Configure USART Rx as alternate function push-pull */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
    GPIO_Init(GPIOA, &GPIO_InitStructure);
    /* USART configuration */
    USART_InitStructure.USART_BaudRate = 9600;
    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(USART2, &USART_InitStructure);