# Block Diagram

The analog input channel is selected by writing to the MUXPOS bit field in the MUXPOS (ADCn.MUXPOS) register. Any of the ADC input pins, GND, internal Voltage Reference (VREF), or temperature sensor, can be selected as a single-ended input to the ADC. The ADC is enabled by writing a ‘1’ to the ENABLE bit in the Control A (ADCn.CTRLA) register. The 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 the ADCn.CTRLA register is ‘0’.