ATmega324P datasheet(242/377 Pages) ATMEL

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242

7674F–AVR–09/09

ATmega164P/324P/644P

• 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 inter-

rupt handling vector. Alternatively, ACI is cleared by writing a logic one to the flag.

• Bit 3 – ACIE: Analog Comparator Interrupt Enable

When the ACIE bit is written logic one and the I-bit in the Status Register is set, the Analog Com-

parator interrupt is activated. When written logic zero, the interrupt is disabled.

• Bit 2 – ACIC: Analog Comparator Input Capture Enable

When written logic one, this bit enables the input capture function in Timer/Counter1 to be trig-

gered by the Analog Comparator. The comparator output is in this case directly connected to the

input capture front-end logic, making the comparator utilize the noise canceler and edge select

features of the Timer/Counter1 Input Capture interrupt. When written logic zero, no connection

between the Analog Comparator and the input capture function exists. To make the comparator

trigger the Timer/Counter1 Input Capture interrupt, the ICIE1 bit in the Timer Interrupt Mask

• Bits 1:0 – ACIS1:ACIS0: Analog Comparator Interrupt Mode Select

These bits determine which comparator events that trigger the Analog Comparator interrupt. The

different settings are shown in Table 20-2.

When changing the ACIS1/ACIS0 bits, the Analog Comparator Interrupt must be disabled by

clearing its Interrupt Enable bit in the ACSR Register. Otherwise an interrupt can occur when the

bits are changed.

20.3.3

DIDR1 – Digital Input Disable Register 1

• Bit 1:0 – AIN1D:AIN0D: AIN1:AIN0 Digital Input Disable

When this bit is written logic one, the digital input buffer on the AIN1/0 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 AIN1/0 pin and the digital input from this pin is not needed, this bit should be writ-

ten logic one to reduce power consumption in the digital input buffer.

Table 20-2.

ACIS1/ACIS0 Settings

ACIS1

ACIS0

Interrupt Mode

Comparator Interrupt on Output Toggle.

Reserved

Comparator Interrupt on Falling Output Edge.

Comparator Interrupt on Rising Output Edge.

Bit

76543210

(0x7F)

–

AIN1D

AIN0D

DIDR1

Read/Write

RRRRRR

R/W

Initial Value

00000000

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