Hi Umesh
If you do not get the waveform available flag indication, then it is most likely that the DSP engine has frozen or switched OFF. Kindly monitor the pin 9 (REF) to see if it is up around 2.4V during this non-responsive period.
Also, how are you sure that the MCU communication is fine during this period?
Schematic suggestions:
1. Tie AGND and DGND pins to the same ground externally.
2. Why have you used a 10 ohm resistor in the AVDD and DVDD supply connection? Why have you used 220uF capacitor there instead of the recommended 10 uF? Also, the capacitive decoupling on RESET pin is missing. Kindly refer to page 13 of the datasheet for recommended connection.
Regards
hmani