ATmega325P datasheet(59/364 Pages) ATMEL

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8023F–AVR–07/09

ATmega325P/3250P

12.2

Pin Change Interrupt Timing

An example of timing of a pin change interrupt is shown in Figure 12-1.

Figure 12-1. Pin Change Interrupt

12.3

12.3.1

EICRA – External Interrupt Control Register A

The External Interrupt Control Register A contains control bits for interrupt sense control.

• Bit 1, 0 – ISC01, ISC00: Interrupt Sense Control 0 Bit 1 and Bit 0

The External Interrupt 0 is activated by the external pin INT0 if the SREG I-flag and the corre-

sponding interrupt mask are set. The level and edges on the external INT0 pin that activate the

interrupt are defined in Table 12-1. The value on the INT0 pin is sampled before detecting

edges. If edge or toggle interrupt is selected, pulses that last longer than one clock period will

generate an interrupt. Shorter pulses are not guaranteed to generate an interrupt. If low level

interrupt is selected, the low level must be held until the completion of the currently executing

instruction to generate an interrupt.

clk

PCINT(n)

pin_lat

pin_sync

pcint_in_(n)

pcint_syn

pcint_setflag

PCIF

PCINT(0)

pin_sync

pcint_syn

pin_lat

pcint_setflag

PCIF

clk

PCINT(0) in PCMSK(x)

pcint_in_(0)

Bit

543210

(0x69)

–

ISC01

ISC00

EICRA

Read/Write

RRRRRR

R/W

Initial Value

000000

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