ADC Operation

The analog input channel is selected by writing to the MUXPOS bits in the MUXPOS register (ADC.MUXPOS). Any of the ADC input pins, GND, internal Voltage Reference (VREF), or temperature sensor, can be selected as single-ended input to the ADC. The ADC is enabled by writing a '1' to the ADC ENABLE bit in the Control A register (ADC.CTRLA). Voltage reference and input channel selections will not go into effect before the ADC is enabled. The ADC does not consume power when the ENABLE bit in ADC.CTRLA is ‘0’. The RESSEL bit in ADC.CTRLA register selects the resolution of ADC to 8 or 10 bits.