Hi Amol, I don't see any large issues with the schematic accept that you will need to have a capacitor at least 330nF between the AVDD and AVSS pins for stability reasons. This is a required capacitor. Also, C33 across the REFOUT and REFCOM pins should be installed as the reference will not be stable without a cap load. The ground for the analog supply (+/-2.5V) should be what is connected to AINCOM. If the digital (3.3V) ground and the analog ground are connected together, then that is ok the way you have it. I would suggest that you do not write to the OFCAL and FSCAL registers. This usually only causes problems. The OFCAL registers will change if you issue an offset calibration. The remaining register settings appear to be ok, although I'm not clear about the INPMUX register setting. If you are trying to measure AIN0, then you should have a setting of 0x0C which is AIN0 connected to AINP and AINCOM connected to AINN. When using the internal reference, you will see positive code values when AIN0 is greater than AINCOM, and negative values when AIN0 is less than AINCOM. This allows for a full-scale range of 5V (+/-2.5V). You cannot measure the internal reference voltage from the ADC directly. You can manually measure the output with a voltmeter by measuring from REFOUT to REFCOM. You can indirectly measure the voltage by comparing the system monitor results when measuring DVDD or (AVDD-AVSS) with calculated results. There will be some noise associated with the measurement, but the mean should be very close to the calculated value. Best regards, Bob B
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