27.2 Analog Comparator Multiplexed Input

It is possible to select any of the ADC[7:0] pins to replace the negative input to the analog comparator. The ADC multiplexer is used to select this input, and consequently, the ADC must be switched off to utilize this feature. If the Analog Comparator Multiplexer Enable bit in the ADC Control and Status Register B (ADCSRB.ACME) is '1' and the ADC is switched off (ADCSRA.ADEN=0), the three least significant analog channel selection bits in the ADC Multiplexer Selection register (ADMUX.MUX[2:0]) select the input pin to replace the negative input to the analog comparator, as shown in the table below. When ADCSRB.ACME=0 or ADCSRA.ADEN=1, AIN1 is applied to the negative input of the analog comparator.

Table 27-1. Analog Comparator Multiplexed Input
ACMEADENMUX[2:0]Analog Comparator Negative Input
0xxxxAIN1
11xxxAIN1
10000ADC0
10001ADC1
10010ADC2
10011ADC3
10100ADC4
10101ADC5
10110ADC6
10111ADC7