20.1 Analog Comparator Multiplexed Input
It is possible to select any of the ADC7:0 pins to replace the negative input to the Analog Com-
parator. 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 (ACME in
ADCSRB) is set and the ADC is switched off (ADEN in ADCSRA is zero), MUX2:0 in ADMUX
select the input pin to replace the negative input to the Analog Comparator, as shown in Table
20-1. If ACME is cleared or ADEN is set, AIN1 is applied to the negative input to the Analog
Comparator.
Table 20-1. Analog Comparator Multiplexed Input
ACME
ADEN
MUX2:0
xxx
Analog Comparator Negative Input
0
1
1
1
1
1
1
1
1
1
x
1
0
0
0
0
0
0
0
0
AIN1
xxx
AIN1
000
001
010
011
100
101
110
111
ADC0
ADC1
ADC2
ADC3
ADC4
ADC5
ADC6
ADC7
212
ATmega169P
8018A–AVR–03/06
ATMEL [ ATMEL ]
