Rainbow-electronics ATmega128L Instrukcja Użytkownika Pobierz pdf (Strona 15)

ATmega128(L)

2467B–09/01

Interrupt Response Time The interrupt execution response for all the enabled AVR interrupts is 4 clock cycles

minimum. After 4 clock cycles, the program vector address for the actual interrupt han-

dling routine is executed. During this 4-clock cycle period, the Program Counter is

pushed onto the Stack. The vector is normally a jump to the interrupt routine, and this

jump takes 3 clock cycles. If an interrupt occurs during execution of a multi-cycle instruc-

tion, this instruction is completed before the interrupt is served. If an interrupt occurs

when the MCU is in sleep mode, the interrupt execution response time is increased by 4

clock cycles. This increase comes in addition to the start-up time from the selected

sleep mode.

A return from an interrupt handling routine takes 4 clock cycles. During these 4-clock

cycles, the Program Counter (2 bytes) is popped back from the Stack, the Stack Pointer

is incremented by 2, and the I-bit in SREG is set.

Assembly Code Example

sei ; set global interrupt enable

sleep ; enter sleep, waiting for interrupt

; note: will enter sleep before any pending

; interrupt(s)

C Code Example

_SEI(); /* set global interrupt enable */

_SLEEP(); /* enter sleep, waiting for interrupt */

/* note: will enter sleep before any pending interrupt(s) */

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Rainbow-electronics ATmega128L Instrukcja Użytkownika Strona 15