When changing the ACIS1/ACIS0 bits, the Analog Comparator Interrupt must be dis-
abled by clearing its Interrupt Enable bit in the ACSR Register. Otherwise an interrupt
can occur when the bits are changed.
Analog Comparator
Multiplexed Input
It is possible to select any of the ADC7..0(1) 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 Multi-
plexer Enable bit (ACME in SFIOR) 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 72. If ACME is cleared or ADEN is set,
AIN1 is applied to the negative input to the Analog Comparator.
Table 72. Analog Comparator Multiplexed Input(1)
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
Note:
1. ADC7..6 are only available in TQFP and MLF Package.
192
ATmega8(L)
2486M–AVR–12/03
ATMEL [ ATMEL ]
