I cannot find a specification for the SAADC converter's reference accuracy. The product specification indicates it is 0.6V, but beyond that I cannot find anything. Looking for absolute accuracy at room temp, over operating temperature range and any drift specification available.
Also, is there any guidance for GPIO voltage and input voltage range for best ADC accuracy? Ie., is it better to have a 3.3V VGPIO and ADC input range up to 3.3V, or a 1.8V VGPIO with ADC input range of 1.8V (assuming external circuitry can bring the input signal to the desired range.) Or, does it matter (ie., could have VGPIO=3.5V with ADC input range of 2.5V and use the internal reference.)
Any general guidance on attaining best ADC accuracy? Ie., better to use internal reference or external reference feeding GPIO (or one of the inputs assuming input signal is single ended.)