I2C2配置是这样的，但是好像用不了
void I2C2_Configuration(void)
{
        I2C_InitTypeDef  I2C_InitStructure;
        GPIO_InitTypeDef  GPIO_InitStructure;

        RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C2,ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB,ENABLE);


        /* PB10,11 SCL and SDA */
        GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_10 | GPIO_Pin_11;
        GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
        GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_OD;
        GPIO_Init(GPIOB, &GPIO_InitStructure);
        
    I2C_DeInit(I2C2);
    I2C_InitStructure.I2C_Mode = I2C_Mode_I2C;
    I2C_InitStructure.I2C_DutyCycle = I2C_DutyCycle_2;
    I2C_InitStructure.I2C_OwnAddress1 = 0x30;
    I2C_InitStructure.I2C_Ack = I2C_Ack_Enable;
    I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;
    I2C_InitStructure.I2C_ClockSpeed = 100000;//100KËù¶è

        I2C_Cmd(I2C2, ENABLE);
        I2C_Init(I2C2, &I2C_InitStructure);
        /*ÔêDí1×Ö½ú1ó|′eÄ￡ê½*/
        I2C_AcknowledgeConfig(I2C2, ENABLE);

   // printf("I2C2_Configuration---- ");
}