I would like to use the internal 1.2V reference as the refernece for the ADC. Both the datasheet and reference manual suggest this should be possible, however it's not obvious how to configure it.
The only options for reference sources in the ADC config are Vrefh orValth. For Valth it says refer to the chip configuration information (which I assume is the datasheet), but there is nothing there either.
If I select the ALR reference, I get results as though the reference voltage is still 3.3V.