/************************ Init ********************************/
  /**
   * @fn DFRobot_AD9837
   * @brief Constructor
   * @param fscPin - active-low control pin, pull down for SPI data transfer
   * @param pSpi - extern SPIClass SPI is defined in SPI.h; so just get SPI object address and the methods in SPI can be pointed to and used
   * @return None
   */
  DFRobot_AD9837(int8_t fscPin=5, SPIClass *pSpi=&SPI);

  /**
   * @fn begin
   * @brief Init function, including SPI communication init, module power-on reset
   * @param frequency - the maximum frequency of SPI communication
   * @return None
   */
  void begin(uint32_t frequency=20000000);

/************************** Config function ******************************/
  /**
   * @fn moduleReset
   * @brief Reset internal registers to 0, this corresponds to an analog output of midscale.
   * @param mode - eReset_EN: reset internal register; eReset_DIS: quit reset status
   * @return None
   * @note RESET operation will not reset the phase, frequency, or control register.
   */
  void moduleReset(eControlRegBit_t mode=eReset_DIS);

  /**
   * @fn moduleSleep
   * @brief The parts of AD9837 that are not in use like the internal clock and DAC can be powered down through the sleep function to minimize power consumption. 
   * @param MCLK - eSleepMCLK_NO: enable internal MCLK; eSleepMCLK_YES: disable internal MCLK. The DAC output remains at its present value as the NCO is no longer
   * @     accumulating.
   * @param dacMode - eSleepDAC_NO: keep DAC active; eSleepDAC_YES: power down on-chip DAC. This is useful when AD9837 is used to output MSB of DAC data.
   * @return None
   * @note  RESET operation will not reset the phase, frequency, or control register.
   */
  void moduleSleep(eControlRegBit_t MCLK=eSleepMCLK_NO, eControlRegBit_t dacMode=eSleepDAC_NO);

/************************** Performance function ******************************/
  /**
   * @fn outputSin
   * @brief OUT  The pin outputs sine wave
   * @param phase - Adjust phase offset, range: 0-360, unit: degree (corresponding to waveform phase offset of 0-2π)
   * @param freq - wave frequency, range: 0.06-8000000.00, unit: Hz
   * @return None
   * @note Recommended frequency range: 60-600000Hz, actual resolution is about 0.06Hz, which is obtained by dividing 16MHz by 2^28 
   */
  void outputSin(uint16_t phase, float freq);

  /**
   * @fn outputTriangle
   * @brief OUT  The pin outputs triangle wave
   * @param phase - adjust phase offset, range: 0-360, unit: degree (corresponding to waveform phase offset of 0-2π)
   * @param freq - wave frequency, range: 0.06-8000000.00, unit: Hz
   * @return None
   * @note Recommended frequency range: 60-600000Hz, actual resolution is about 0.06Hz, which is obtained by dividing 16MHz by 2^28
   */
  void outputTriangle(uint16_t phase, float freq);

  /**
   * @fn outputSquare
   * @brief OUT  The pin outputs square wave
   * @param divide - eDIV2_2: MSB/2 of DAC data is output through VOUT pin; eDIV2_1: MSB of DAC data is output via VOUT pin.
   * @param phase - adjust phase offset, range: 0-360, unit: degree (corresponding to waveform phase offset of 0-2π)
   * @param freq - wave frequency, range: 0.06-8000000.00, unit: Hz
   * @return None
   * @note Recommended frequency range: 60-600000Hz, actual resolution is about 0.06Hz, which is obtained by dividing 16MHz by 2^28
   */
  void outputSquare(eControlRegBit_t divide, uint16_t phase, float freq);