IIC 出现硬件错误

static struct rt_i2c_bus_device *i2c_bus = RT_NULL;     /* I2C总线设备句柄 */
     i2c_bus = (struct rt_i2c_bus_device *)rt_device_find("i2c2");   
        if (i2c_bus == RT_NULL){        
            uart_debug("can't find i2c2  device!\n");   
            return RT_ERROR;
        }