Datasheet

291
7766F–AVR–11/10
ATmega16/32U4
23.1 Analog Comparator Multiplexed Input
It is possible to select any of the ADC13..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), and MUX2..0 in
ADMUX select the input pin to replace the negative input to the Analog Comparator, as shown in
Table 23-2. If ACME is cleared or ADEN is set, the Bandgap reference is applied to the negative
input to the Analog Comparator.
23.1.1 Digital Input Disable Register 1 – DIDR1
• Bit 0 – AIN0D: AIN0 Digital Input Disable
When this bit is written logic one, the digital input buffer on the AIN0 pin is disabled. The corre-
sponding PIN Register bit will always read as zero when this bit is set. When an analog signal is
applied to the AIN0 pin and the digital input from this pin is not needed, this bit should be written
logic one to reduce power consumption in the digital input buffer.
Table 23-2. Analog Comparator Multiplexed Input
ACME ADEN MUX2..0 Analog Comparator Negative Input
0 x xxx Bandgap Ref.
1 1 xxx Bandgap Ref.
1 0 000 ADC0
1 0 001 ADC1
10010
N/A
10011
1 0 100 ADC4
1 0 101 ADC5
1 0 110 ADC6
1 0 111 ADC7
Bit 76543210
– – – – – – – AIN0D DIDR1
Read/WriteRRRRRRRR/W
Initial Value00000000