ATMEGA644PV ATMEL [ATMEL Corporation], ATMEGA644PV Datasheet - Page 235

• Manufacturer Part Number: ATMEGA644PV
• Description: 8-bit Microcontroller with 16/32/64K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

20. AC - Analog Comparator
20.1
20.2
8011D–AVR–02/07
Overview
Analog Comparator Multiplexed Input
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 com-
parator 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
be disabled by writing a logical zero to be able to use the ADC input MUX.
Figure 20-1. Analog Comparator Block Diagram
Notes:
It is possible to select any of the ADC7..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), MUX2..0 in ADMUX
select the input pin to replace the negative input to the Analog Comparator, as shown in
20-1 on page
Analog Comparator.
Table 20-1.
ACME
0
1
1
ADC MULTIPLEXER
1. See
2. Refer to
Figure
REFERENCE
ACME
ADEN
BANDGAP
OUTPUT
placement.
235. If ACME is cleared or ADEN is set, AIN1 is applied to the negative input to the
Analog Comparator Mulitiplexed Input
Table 20-1 on page
(1)
20-1.
ACBG
Figure 1-1 on page 2
ADEN
1
0
x
235.
MUX2..0
000
xxx
xxx
and
”PRR – Power Reduction Register” on page 48
Table 12-5 on page 80
Analog Comparator Negative Input
AIN1
AIN1
ADC0
ATmega164P/324P/644P
(2)
for Analog Comparator pin
Table
must
235