/**
     * @fn begin
     * @brief initialization function
     * @return initialization status
     * @retval ERR_OK          initialization success
     * @retval ERR_DATA_BUS    error in data bus
     * @retval ERR_IC_VERSION  chip version mismatch
     */ 
    int begin();

    /**
     * @fn checkDataReady
     * @brief Judge if there is data to read 
     * @return  the result of checking
     * @retval  true   there is
     * @retval  false  there is no
     */
    bool checkDataReady();

    /**
     * @fn softReset
     * @brief Reset sensor, clear all configured data.
     */
    void softReset();

    /**
     * @fn setInTempHum
     * @brief Set environment parameter 
     * @param temperature Set temperature value, unit: centigrade, range (-40~85℃)
     * @param humidity    Set humidity value, unit: RH, range (0~100)
     */
    void setInTempHum(float temperature, float humidity);

    /**
     * @fn setMeasurementMode
     * @brief Measurement parameter configuration 
     * @param mode:Measurements mode
     * @n            eClosed       Idle (Measurements are disabled in this mode)
     * @n            eCycle_1s     Constant power mode, IAQ measurement every second
     * @n            eCycle_10s    Pulse heating mode IAQ measurement every 10 seconds
     * @n            eCycle_60s    Low power pulse heating mode IAQ measurement every 60 seconds
     * @n            eCycle_250ms  Constant power mode, sensor measurement every 250ms 1xx: Reserved modes (For future use)
     * @param thresh
     * @n            0             for Interrupt mode operates normally
     * @n            1             for interrupt mode only asserts the nINT signal (driven low) if the new
     * @param interrupt
     * @n            0             for Interrupt generation is disabled
     * @n            1             for the nINT signal is asserted (driven low) when a new sample is ready in
     */
    void setMeasurementMode(eCycle_t mode, uint8_t thresh = 0, uint8_t interrupt = 0);

    /**
     * @fn setThresholds
     * @brief Set interrupt thresholds 
     * @param lowToMed: interrupt triggered value in range low to middle 
     * @param medToHigh: interrupt triggered value in range middle to high 
     */
    void setThresholds(uint16_t lowToMed, uint16_t medToHigh);

    /**
     * @fn getMeasurementMode
     * @brief Get current configured parameter
     * @return configuration code, needs to be converted into binary code to analyze
     * @n       The 2nd: Interrupt mode (if enabled) operates normally,1: Interrupt mode (if enabled) only asserts the nINT signal (driven low) if the new
     * @n       The 3rd: Interrupt generation is disabled,1: The nINT signal is asserted (driven low) when a new sample is ready in
     * @n       The 4th: 6th: in typedef enum eCycle_t
     */
    uint8_t getMeasurementMode();

    /**
     * @fn getCO2PPM
     * @brief Get the current carbon dioxide concentration
     * @return current carbon dioxide concentration, unit:ppm
     */
    uint16_t getCO2PPM();

    /**
     * @fn getTVOCPPB
     * @brief Get current TVOC concentration
     * @return Return current TVOC concentration, unit: ppb
     */
    uint16_t getTVOCPPB();

    /**
     * @fn readBaseLine
     * @brief get the current baseline number
     * @return a Hexadecimal number of the current baseline number
     */
    uint16_t readBaseLine();

    /**
     * @fn writeBaseLine
     * @brief write a baseline number into register
     * @param baseLine Hexadecimal number get from baseLine()
     */
    void writeBaseLine(uint16_t baseLine);