I am trying to read the voltage of a battery using the SAR ADC but I am not getting the correct values. The ADC outputs 0x7FF0 no matter what the voltage is I am trying to measure. I am using a voltage divider with 357K ohm resistors and an input voltage of 3.8V though this can go as low as 2.5V. The ADC is using an internal Vref of 1.024V. Any help would be appreciated.