ATmega32A datasheet(205/352 Pages) ATMEL

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205

8155B–AVR–07/09

ATmega32A

21. Analog Comparator

21.1

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 com-

parator output rise, fall or toggle. A block diagram of the comparator and its surrounding logic is

shown in Figure 21-1

Figure 21-1. Analog Comparator Block Diagram

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Notes:

1. See Table 21-1 on page 206.

2. Refer to Figure 1-1 on page 2 and Table 12-6 on page 59 for Analog Comparator pin

placement.

21.2

Analog Comparator Multiplexed Input

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

SFIOR) 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 Table

ACBG

BANDGAP

REFERENCE

ADC MULTIPLEXER

OUTPUT

ACME

ADEN

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