Table 25-1. Analog Comparator Mulitiplexed Input
ACME
ADEN
MUX5
MUX2:0
100
101
110
111
000
001
010
011
100
101
110
111
Analog Comparator Negative Input
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
ADC4
ADC5
ADC6
ADC7
ADC8
ADC9
ADC10
ADC11
ADC12
ADC13
ADC14
ADC15
25.2 Register Description
25.2.1
ADCSRB – ADC Control and Status Register B
Bit
7
–
6
ACME
R/W
0
5
–
4
–
3
2
ADTS2
R/W
0
1
ADTS1
R/W
0
0
ADTS0
R/W
0
(0x7B)
MUX5
R/W
0
ADCSRB
Read/Write
Initial Value
R
0
R
0
R
0
• Bit 6 – ACME: Analog Comparator Multiplexer Enable
When this bit is written logic one and the ADC is switched off (ADEN in ADCSRA is zero), the
ADC multiplexer selects the negative input to the Analog Comparator. When this bit is written
logic zero, AIN1 is applied to the negative input of the Analog Comparator. For a detailed
description of this bit, see “Analog Comparator Multiplexed Input” on page 271.
25.2.2
ACSR – Analog Comparator Control and Status Register
Bit
0x30 (0x50)
7
6
5
4
3
ACIE
R/W
0
2
ACIC
R/W
0
1
ACIS1
R/W
0
0
ACIS0
R/W
0
ACD
ACBG
ACO
ACI
ACSR
Read/Write
R/W
R/W
R
R/W
Initial Value
0
0
N/A
0
• Bit 7 – ACD: Analog Comparator Disable
When this bit is written logic one, the power to the Analog Comparator is switched off. This bit
can be set at any time to turn off the Analog Comparator. This will reduce power consumption in
Active and Idle mode. When changing the ACD bit, the Analog Comparator Interrupt must be
disabled by clearing the ACIE bit in ACSR. Otherwise an interrupt can occur when the bit is
changed.
• Bit 6 – ACBG: Analog Comparator Bandgap Select
272
ATmega640/1280/1281/2560/2561
2549L–AVR–08/07
ATMEL [ ATMEL ]
