
216
ATmega64A [DATASHEET]
8160D–AVR–02/2013
23.2
Register Description
23.2.1
SFIOR – Special Function IO Register
Bit 3 – 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 neg-
23.2.2
ACSR – Analog Comparator Control and Status Register
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 chang-
ing 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
When this bit is set, a fixed bandgap reference voltage replaces the positive input to the Analog Comparator. When
Bit 5 – ACO: Analog Comparator Output
The output of the Analog Comparator is synchronized and then directly connected to ACO. The synchronization
introduces a delay of 1 - 2 clock cycles.
Bit 4 – ACI: Analog Comparator Interrupt Flag
This bit is set by hardware when a comparator output event triggers the interrupt mode defined by ACIS1 and
ACIS0. The Analog Comparator Interrupt routine is executed if the ACIE bit is set and the I-bit in SREG is set. ACI
is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, ACI is cleared by
writing a logic one to the flag.
10
100
ADC4
10
101
ADC5
10
110
ADC6
10
111
ADC7
Table 23-1.
Analog Comparator Multiplexed Input (Continued)
ACME
ADEN
MUX2:0
Analog Comparator Negative Input
Bit
7
6
5
4
3
2
1
0
TSM
–
ACME
PUD
PSR2
PSR10
SFIOR
Read/Write
R/W
R
R/W
Initial Value
0
Bit
7654
3210
ACD
ACBG
ACO
ACI
ACIE
ACIC
ACIS1
ACIS0
ACSR
Read/Write
R/W
R
R/W
Initial Value
0
N/A
0
0000