Atmel ATmega328P Xplained Mini MEGA328P-XMINI MEGA328P-XMINI Ficha De Dados
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MEGA328P-XMINI
235
ATmega48A/PA/88A/PA/168A/PA/328/P [DATASHEET]
Atmel-8271H-AVR- ATmega-Datasheet_08/2014
23.
Analog Comparator
23.1
Overview
The Analog Comparator compares the input values on the positive pin AIN0 and negative pin AIN1. When the
voltage on the positive pin AIN0 is higher than the voltage on the negative pin AIN1, the Analog Comparator
output, ACO, is set. The comparator’s output can be set to trigger the Timer/Counter1 Input Capture function. In
addition, the comparator can trigger a separate interrupt, exclusive to the Analog Comparator. The user can
select Interrupt triggering on comparator output rise, fall or toggle. A block diagram of the comparator and its
surrounding logic is shown in
voltage on the positive pin AIN0 is higher than the voltage on the negative pin AIN1, the Analog Comparator
output, ACO, is set. The comparator’s output can be set to trigger the Timer/Counter1 Input Capture function. In
addition, the comparator can trigger a separate interrupt, exclusive to the Analog Comparator. The user can
select Interrupt triggering on comparator output rise, fall or toggle. A block diagram of the comparator and its
surrounding logic is shown in
.
The Power Reduction ADC bit, PRADC, in
must be disabled by
writing a logical zero to be able to use the ADC input MUX.
Figure 23-1.
Analog Comparator Block Diagram
Notes: 1. See
2. Refer to
and
for Analog Comparator pin placement.
23.2
Analog Comparator Multiplexed Input
It is possible to select any of the ADC7...0 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 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
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
. If ACME is cleared or ADEN is set, AIN1 is applied to the negative input to
the Analog Comparator.
ACBG
BANDGAP
REFERENCE
ADC MULTIPLEXER
OUTPUT
ACME
ADEN
ADEN
(1)
Table 23-1.
Analog Comparator Multiplexed Input
ACME
ADEN
MUX2...0
Analog Comparator Negative Input
0
x
xxx
AIN1
1
1
xxx
AIN1
1
0
000
ADC0
1
0
001
ADC1
1
0
010
ADC2
1
0
011
ADC3