23.3.2 Voltage Measurement

The VDDIOx supply voltage is available as an internal input channel to the ADC. The voltage is divided by ten to allow the use of any internal ADC reference. This internal input channel to the ADC should only be used to measure the MVIO supply voltage once the VDDIOx voltage domain has been released from POR and the voltage domain is ready to use as indicated by the RDY status bit and the VDDIOxPORFIF interrupt flag. To measure VDDIOx/10, it is recommended to follow these steps:
  1. Ensure that the VDDIOx domain is active using the respective MVIO voltage monitors.
  2. Configure the voltage reference for the ADC.
  3. Select VDDIOx/10 as the positive input to the ADC.
  4. Run a single-ended ADC conversion.
  5. Calculate the voltage using the following equation:
    V DDIOx = ADC Result × V REF × 10 ADC Resolution